An MVC-based web application framework. Includes routing, serving, caching, and other helpful tools.
citizen is an MVC-based web application framework designed for people who are more interested in quickly building fast, scalable apps than digging around Node's guts or cobbling together a Jenga tower made out of 20 different packages.
Use citizen as a foundation for a traditional server-side web application, a modular single-page app, or a REST API.
async await and vanilla return statements replace event emitter controller actionscitizen's API is stabilizing, but it's still subject to change. Always consult the change log before upgrading. Version 0.9.x has significant breaking changes compared to 0.8.x.
Have questions, suggestions, or need help? Send me an e-mail. Want to contribute? Pull requests are welcome.
I use it on originaltrilogy.com. We get a moderate amount of traffic (averaging ~400k page views per month and peaking at 750k) and the site runs for months on end without the app/process crashing. It's very stable.
These commands will create a new directory for your web app, install citizen, use its scaffolding utility to create the app's skeleton, and start citizen with the web server listening on port 8080 (citizen defaults to port 80, but it's often in use already, so change it to whatever you want):
$ mkdir mywebapp
$ cd mywebapp
$ npm install citizen
$ node node_modules/citizen/util/scaffold skeleton -n 8080
$ node app/start.js
If everything went well, you'll see confirmation in the console that citizen is listening on the specified port. Go to http://127.0.0.1:8080 in your browser and you'll see a bare index template.
citizen installs Handlebars as its default template engine, but you can install any template engine supported by consolidate.js, update the config template settings, and modify the default view templates accordingly.
For configuration options, see Configuration. For more utilities to help you get started, see Utilities.
/app
/config // These files are all optional
citizen.json // Default config file
local.json // Examples of environment configs
qa.json
prod.json
/hooks // Application event hooks (optional)
application.js
request.js
response.js
session.js
/logs // Log files created by citizen and your app
app.log
citizen.log
/patterns
/controllers // Controllers
index.js
/models // Models (optional)
index.js
/views
/error
error.hbs // Default error view
/index
index.hbs // Default index view
other.hbs // Alternate index view (optional)
start.js
/web // public static assets
The start.js file in your app directory can be as simple as this:
// start.js
global.app = require('citizen')
app.start()
Run start.js from the command line:
$ node start.js
The config directory is optional and contains configuration files that drive both citizen and your app in JSON format. You can have multiple citizen configuration files within this directory, allowing different configurations based on environment. citizen retrieves its configuration file from this directory based on the following logic:
host key that matches the machine's hostname. If it finds one, it loads that configuration.host key, it looks for a file named citizen.json and loads that configuration.Let's say you want to run citizen on port 8080 in your local dev environment and you have a local database your app will connect to. You could create a config file called local.json (or myconfig.json, whatever you want) with the following:
{
"host": "My-MacBook-Pro.local",
"citizen": {
"mode": "development",
"http": {
"port": 8080
}
},
"db": {
"server": "localhost",
"username": "dbuser",
"password": "dbpassword"
}
}
This config would extend the default configuration only when running on your local machine. If you were to push this to a production environment accidentally, it wouldn't do anything. Using this method, you can commit multiple config files from different environments to the same repository.
The database settings would be accessible within your app via app.config.db. The citizen and host nodes are reserved for the framework; create your own node(s) to store your custom settings.
You can also pass your app's configuration directly to citizen through app.start(). If there is a config file, an inline config will extend the config file. If there's no config file, the inline configuration extends the default citizen config.
// Start an HTTP server on port 8080 accepting requests at www.mysite.com
app.start({
citizen: {
http: {
hostname: 'www.mysite.com',
port: 8080
}
}
})
// Start an HTTPS server with key and cert PEM files
app.start({
citizen: {
http: {
enable: false
},
https: {
enable: true,
key: '/absolute/path/to/key.pem',
cert: '/absolute/path/to/cert.pem'
}
}
})
// Start an HTTPS server with a PFX file running on port 3000,
// and add a custom namespace for your app's database config
app.start({
citizen: {
http: {
enable: false
},
https: {
enable: true,
port: 3000,
pfx: '/absolute/path/to/site.pfx'
}
},
db: {
server: "localhost", // app.config.db.server
username: "dbuser", // app.config.db.username
password: "dbpassword" // app.config.db.password
}
})
The following represents citizen's default configuration, which is extended by your configuration:
{
host : "",
citizen: {
mode : "production",
http: {
enable : true,
hostname : "127.0.0.1",
port : 80
},
https: {
enable : false,
hostname : "127.0.0.1",
port : 443,
secureCookies : true
},
connectionQueue : null,
fallbackController : "",
templateEngine : "handlebars",
compression: {
enable : false,
force : false,
mimeTypes : "text/plain text/html text/css application/x-javascript application/javascript text/xml application/xml application/xml+rss text/javascript image/svg+xml"
},
sessions : false,
sessionTimeout : 20,
layout: {
controller : "",
view : ""
},
legalFormats: {
html : true,
json : false,
jsonp : false
},
form: {},
cache: {
application: {
enable : true,
lifespan : 15,
resetOnAccess : true,
overwrite : false,
encoding : "utf-8",
synchronous : false
},
static: {
enable : false,
lifespan : 15,
resetOnAccess : true
},
control : {}
},
log: {
console: {
colors : true,
error : false,
status : false
},
file: {
error : false,
status : false,
maxFileSize : 10000,
watcher: {
interval : 60000
}
}
},
development: {
debug: {
scope: {
config : true,
context : true,
cookie : true,
form : true,
payload : true,
request : true,
response : true,
route : true,
session : true,
url : true,
},
depth : 3,
showHidden : false,
view : false
},
enableCache : false,
watcher: {
custom : [],
interval : 500,
killSession : false
}
},
urlPaths: {
app : "/"
},
directories: {
app : "[resolved based on location of start.js]",
hooks : "[directories.app]/hooks",
logs : "[directories.app]/logs",
controllers : "[directories.app]/patterns/controllers",
models : "[directories.app]/patterns/models",
views : "[directories.app]/patterns/views",
web : "web"
}
}
}
When starting an HTTPS server, in addition to the hostname and port options, citizen takes the same options as Node's https.createServer() (which takes the same options as tls.createServer()).
The only difference is how you pass key files. As you can see in the examples above, you pass citizen the file paths for your key files. citizen reads the files for you.
Here's a complete rundown of citizen's settings and what they mean:
| Setting | Values | Description |
|---|---|---|
host
|
The operating system's hostname |
To load different config files in different environments, citizen relies upon the server's hostname as a key. At startup, if citizen finds a config file with a host key that matches the server's hostname, it chooses that config file. This is different from the HTTP hostname setting under the citizen node (see below).
|
| citizen | ||
mode
|
Default: | The application mode determines certain runtime behaviors. Production mode silences console logs and enables all application features. Development mode enables verbose console logs, disables caching, and enables the file watcher for hot module reloading for controllers, models, and hooks. |
| http | ||
enable
|
Boolean
Default: | This setting controls the HTTP server, which is enabled by default. |
hostname
|
String
Default: | The hostname at which your app can be accessed via HTTP. The default is localhost, but you can specify an empty string to accept requests at any hostname. |
port
|
Number
Default: | The port number on which citizen's HTTP server should listen for requests. |
| https | ||
enable
|
Boolean
Default: | This setting controls the HTTPS server, which is disabled by default. |
hostname
|
String
Default: | The hostname at which your app can be accessed via HTTPS. The default is localhost, but you can specify an empty string to accept requests at any hostname. |
port
|
Number
Default: | The port number on which citizen's HTTPS server should listen for requests. |
secureCookies
|
Boolean
Default: |
By default, all cookies set during an HTTPS request are secure. Set this option to false to override that behavior, making all cookies insecure and requiring you to manually set the secure option in the cookie directive.
|
connectionQueue
|
A positive integer
Default: | The maximum number of incoming requests to queue. If left unspecified, the operating system determines the queue limit. |
sessions
|
Boolean
Default: | Enables the user session scope, which assigns each visitor a unique ID and allows you to store data associated with that ID on the server. |
sessionTimeout
|
Positive integer
Default: | If sessions are enabled, this number represents the length of a user's session in minutes. Sessions automatically expire if a user has been inactive for this amount of time. |
| layout | ||
controller
|
String Default: (empty) | If you use a global layout controller, you can specify the name of that controller here instead of using the handoff directive in all your controllers. |
view
|
String Default: (empty) | By default, the layout controller will use the default layout view, but you can specify a different view here. Use the file name without the file extension. |
templateEngine
|
String
Default: | citizen installs Handlebars by default, but you can change the template engine to any engine supported by consolidate.js. |
| legalFormats | ||
html
|
Boolean
Default: | citizen provides HTML output by default based on your views. You can disable HTML entirely if you plan to use citizen for building an API that returns JSON or JSONP only. |
json
|
Boolean
Default: |
JSON output is disabled by default. Set this value to true to enable global JSON output from all controllers. To enable JSON at the controller action level, see the legalFormats directive and JSON and JSONP for details.
|
jsonp
|
Boolean
Default: |
JSONP output is disabled by default. Set this value to true to enable global JSONP output from all controllers. To enable JSONP at the controller action level, see the legalFormats directive and JSON and JSONP for details.
|
| form | ||
{ options }
|
Object Default: Same as formidable | citizen uses formidable to parse form data. The defaults match that of formidable. Provide settings in the form node to set default settings for all your forms. See Forms for details. |
| compression | ||
enable
|
Boolean
Default: | Enables gzip and deflate compression for rendered views and static assets. |
force
|
Boolean or String
Default: |
Forces gzip or deflate encoding for all clients, even if they don't report accepting compressed formats. Many proxies and firewalls break the Accept-Encoding header that determines gzip support, and since all modern clients support gzip, it's usually safe to force it by setting this to gzip, but you can also force deflate.
|
mimeTypes
|
String | A space-delimited list of MIME types that should be compressed if compression is enabled. See the sample config above for the default list. If you want to add or remove items, you must replace the list in its entirety. |
| cache | ||
| application | ||
enable
|
Boolean
Default: |
Enables the in-memory cache, accessed via the cache.set() and cache.get() methods. Set this to false to disable the cache when in production mode, which is useful for debugging when not in development mode.
|
lifespan
|
Number
Default: | The length of time a cached application asset remains in memory, in minutes. |
resetOnAccess
|
Boolean
Default: |
Determines whether to reset the cache timer on a cached asset whenever the cache is accessed. When set to false, cached items expire when the lifespan is reached.
|
overwrite
|
Boolean
Default: |
Determines whether a call to cache.set() will overwrite an existing cache key. By default, an error is thrown if the cache key already exists. You can either pass the overwrite flag as an option in cache.set() or set this to true to always overwrite.
|
encoding
|
String
Default: | When you pass a file path to cache.set(), the encoding setting determines what encoding should be used when reading the file. |
synchronous
|
Boolean
Default: | When you pass a file path to cache.set(), this setting determines whether the file should be read synchronously or asynchronously. By default, file reads are asynchronous. |
| static | ||
enable
|
Boolean
Default: |
When serving static files, citizen normally reads the file from disk for each request. You can speed up static file serving considerably by setting this to true, which caches file buffers in memory.
|
lifespan
|
Number
Default: | The length of time a cached static asset remains in memory, in minutes. |
resetOnAccess
|
Boolean
Default: |
Determines whether to reset the cache timer on a cached static asset whenever the cache is accessed. When set to false, cached items expire when the lifespan is reached.
|
control
|
Key/value pairs
Default: | Use this setting to set Cache-Control headers for static assets. The key is the pathname of the asset, and the value is the Cache-Control header. See Client-Side Caching for details. |
| log | ||
| console | ||
colors
|
Boolean
Default: | Enables color coding in console logs. |
error
|
Boolean
Default: | Controls whether errors should be logged to the console. |
status
|
Boolean
Default: | Controls whether status messages should be logged to the console when in production mode. (Development mode always logs to the console.) |
| file | ||
error
|
Boolean
Default: | Controls whether errors should be logged to a file. |
status
|
Boolean
Default: | Controls whether status messages should be logged to a file. Applies to both development and production modes. |
maxFileSize
|
Number
Default: | Determines the maximum file size of log files in kilobytes. Default is 10000 (10 megs). When the limit is reached, the log file is renamed and a new log file is created. |
| watcher | ||
interval
|
Number
Default: | For operating systems that don't support file events, this timer (in milliseconds) determines how often log files will be polled for changes prior to archiving. |
| development | ||
| debug | ||
scope
|
Object | This setting determines which scopes are logged in the debug output in development mode. By default, all scopes are enabled. |
depth
|
Positive integer
Default: | When citizen dumps an object in the debug content, it inspects it using Node's util.inspect. This setting determines the depth of the inspection, meaning the number of nodes that will be inspected and displayed. Larger numbers mean deeper inspection and slower performance. |
view
|
Boolean
Default: | Set this to true to dump debug info directly into the HTML view. |
enableCache
|
Boolean
Default: |
Development mode disables the cache. Change this setting to true to enable the cache in development mode.
|
| watcher | ||
custom
|
Array |
You can tell citizen's hot module reloader to watch your own custom modules. This array can contain objects with watch (relative directory path to your modules within the app directory) and assign (the variable to which you assign these modules) properties. Example:
[ { "watch": "/toolbox", "assign": "app.toolbox" } ]
|
interval
|
Number
Default: | Determines the polling interval in milliseconds for hot module reloading on operating systems that don't support file system events. Shorter intervals are more CPU intensive. |
| urlPaths | ||
app
|
String
Default: |
Denotes the URL path leading to your app. If you want your app to be accessible via http://yoursite.com/my/app and you're not using another server as a front end to proxy the request, this setting should be /my/app (don't forget the leading slash). This setting is required for the router to work.
|
These settings are exposed publicly via app.config.host and app.config.citizen.
Note: This documentation assumes your global app variable name is "app", but you can call it whatever you want. Adjust accordingly.
app.start()
| Starts a citizen web application server. |
app.cache.set()app.cache.exists()app.cache.get()app.cache.clear()app.log()
| Helpers used internally by citizen, exposed publicly since you might find them useful. |
app.controllersapp.models
|
Contains your supplied patterns, which you can use instead of require.
|
app.config
| The configuration settings you supplied at startup |
The citizen URL structure determines which controller and action to fire, passes URL parameters, and makes a bit of room for SEO-friendly content that can double as a unique identifier. The structure looks like this:
http://www.site.com/controller/seo-content/action/myAction/param/val/param2/val2
For example, let's say your site's base URL is:
http://www.cleverna.me
The default controller is index, so the above is the equivalent of the following:
http://www.cleverna.me/index
If you have an article controller, you'd request it like this:
http://www.cleverna.me/article
Instead of query strings, citizen uses an SEO-friendly method of passing URL parameters consisting of name/value pairs. If you had to pass an article ID of 237 and a page number of 2, you'd append name/value pairs to the URL:
http://www.cleverna.me/article/id/237/page/2
Valid parameter names may contain letters, numbers, underscores, and dashes, but must start with a letter or underscore.
The default controller action is handler(), but you can specify alternate actions with the action parameter (more on this later):
http://www.cleverna.me/article/action/edit
citizen also lets you optionally insert relevant content into your URLs, like so:
http://www.cleverna.me/article/My-Clever-Article-Title/page/2
This SEO content must always follow the controller name and precede any name/value pairs. You can access it generically via route.descriptor or within the url scope (url.article in this case), which means you can use it as a unique identifier (more on URL parameters in the Controllers section).
The SEO content can consist of letters, numbers, dots (.), and the tilde (~) character.
citizen relies on a simple model-view-controller convention. The article pattern mentioned above might use the following structure:
app/
patterns/
controllers/
article.js
models/
article.js
views/
article/ // Directory name matches the controller name
article.hbs // Default view name matches the controller name
edit.hbs // Secondary view, which must be called explicitly
At least one controller is required for a given URL, and a controller's default view directory and default view file must share its name. Additional views should reside in this same directory. More on views in the Views section.
Models and views are optional and don't necessarily need to be associated with a particular controller. If your controller doesn't need a model, you don't need to create one. If your controller is going to pass its output to another controller for further processing and final rendering, you don't need to include a matching view. (See the controller handoff directive.)
A citizen controller is just a Node module. Each controller requires at least one public method to serve as an action for the requested route. The default action should be named handler(), which is called by citizen when no action is specified in the URL.
// article controller
module.exports = {
handler: handler
}
// Default action
async function handler(params, context) {
// Do some stuff
return {
// Send content and directives to the server
}
}
The citizen server calls handler() after it processes the initial request and passes it 2 arguments: an object containing the parameters of the request and the current request's context.
request | The request object generated by the server, just in case you need direct access |
response | The response object generated by the server |
route | Details of the route, such as the requested URL and the name of the route (controller) |
url | Any URL parameters that were passed including the descriptor, if provided |
form | Data collected from a POST |
payload | Data collected from a PUT |
cookie | An object containing any cookies sent with the request |
session | An object containing any session variables, if sessions are enabled |
In addition to having access to these objects within your controller, they are also included in your view context automatically so you can reference them within your view templates as local variables (more details in the Views section).
For example, based on the previous article URL...
http://www.cleverna.me/article/My-Clever-Article-Title/page/2
...you'll have the following params.url object passed to your controller:
{
article: 'My-Clever-Article-Title',
page: '2'
}
The controller name becomes a property in the URL scope that references the descriptor, which makes it well-suited for use as a unique identifier. This content is also available in the params.route object as route.descriptor.
The context argument contains any data that's been generated by the request up to this point. There are various events that can populate this argument with content and directives, which are then passed to your controller so you can access that content or see what directives have been set by previous events.
To return the results of the controller action, include a return statement with any content and directives you want to pass to citizen.
Using the above URL parameters, I can retrieve the article content from the model and pass it back to the server:
// article controller
module.exports = {
handler: handler
}
async function handler(params, context) {
// Get the article
const article = await app.models.article.getArticle({
article: params.url.article,
page: params.url.page
})
const author = await app.models.article.getAuthor({
author: article.author
})
// Return the article for view rendering using the content directive
return {
content: {
article: article,
author: author
}
}
}
Alternate actions can be requested using the action URL parameter. For example, maybe we want a different action and view to edit an article:
// http://www.cleverna.me/article/My-Clever-Article-Title/page/2/action/edit
// article controller
module.exports = {
handler: handler,
edit: edit
}
async function handler(params, context) {
// Get the article
const article = await app.models.article.getArticle({
article: params.url.article,
page: params.url.page
})
const author = await app.models.article.getAuthor({
author: article.author
})
// Return the article for view rendering using the content directive
return {
content: {
article: article,
author: author
}
}
}
async function edit(params, context) {
// Get the article
const article = await app.models.article.getArticle({
article: params.url.article,
page: params.url.page
})
// Use the /patterns/views/article/edit.hbs view for this action (more on
// alternate views in later sections).
return {
content: {
article: article
},
view: 'edit'
}
}
You place any data you want to pass back to citizen within the return statement. All the content you want to render in your view should be passed to citizen within an object called content, as shown above. Additional objects can be passed to citizen to set directives that provide instructions to the server (explained later in the Controller Directives section). You can even add your own objects to the request context and pass them from controller to controller (more in the Controller Handoff section.)
To make a controller private—inaccessible via HTTP, but accessible within your app—add a plus sign (+) to the beginning of the file name:
app/
patterns/
controllers/
+_header.js // Partial, only accessible internally
_head.js // Partial, accessible via www.cleverna.me/_head
article.js // Accessible via www.cleverna.me/article
If you want to make a controller action available to third parties, see the CORS section.
Models are optional and their structure is completely up to you. citizen doesn't talk to your models directly; it only stores them in app.models for your convenience.
Here's what a simple model for the article pattern might look like:
// article model
module.exports = {
getArticle: getArticle
}
async function getArticle(article, page) {
const client = await app.db.connect()
const result = await client.query({
text: 'select title, summary, text, author, published from articles where id = $1 and page = $2;',
values: [ article, page ]
})
client.release()
return result.rows
}
async function getAuthor(author) {
const client = await app.db.connect()
const result = await client.query({
text: 'select name, email from users where id = $1;',
values: [ author ]
})
client.release()
return result.rows
}
citizen installs Handlebars by default, but you can install any engine supported by consolidate.js and set the templateEngine config setting accordingly. Make sure you use the correct file extension with your views so citizen knows how to parse them. citizen only supports one template engine at a time; you can't mix and match templates.
In article.hbs, you can reference objects you placed within the content object passed into the controller's return statement. citizen also injects the params object into your view context automatically, so you have access to those objects as local variables (such as the url scope):
{{! article.hbs }}
<!doctype html>
<html>
<body>
<main>
<h1>
{{article.title}} — Page {{url.page}}
</h1>
<h2>{{author.name}}, {{article.published}}</h2>
<p>
{{article.summary}}
</p>
<section>
{{article.text}}
</section>
</main>
</body>
</html>
By default, the server renders the view whose name matches that of the controller. To render a different view, use the view directive in your return statement.
You can tell a controller to return its content as JSON by adding the format URL parameter, letting the same resource serve both a complete HTML view and JSON for AJAX requests and RESTful APIs.
http://www.cleverna.me/article/My-Clever-Article-Title/page/2/format/json
Returns...
{
"article": {
"title": "My Clever Article Title",
"summary": "Am I not terribly clever?",
"text": "This is my article text."
},
"author": {
"name": "John Smith",
"email": "jsmith@cleverna.me"
}
}
Whatever you've added to the controller's return statement content object will be returned.
To enable JSON output at the controller level:
return {
content: {
article: article,
author: author
},
legalFormats: {
json: true
}
}
You can also specify indivdidual nodes to return instead of returning the entire content object by using the output URL parameter:
http://www.cleverna.me/article/My-Clever-Article-Title/page/2/format/json/output/author
Returns...
{
"name": "John Smith",
"email": "jsmith@cleverna.me"
}
Use dash notation in the output parameter to go deeper into the node tree:
http://www.cleverna.me/article/My-Clever-Article-Title/page/2/format/json/output/author-email
Returns...
jsmith@cleverna.me
For JSONP, use format paired with callback in the URL:
http://www.cleverna.me/article/My-Clever-Article-Title/format/jsonp/callback/foo
Returns:
foo({
"article": {
"title": "My Clever Article Title",
"summary": "Am I not terribly clever?",
"text": "This is my article text."
},
"author": {
"name": "John Smith",
"email": "jsmith@cleverna.me"
}
})
To enable JSONP output at the controller level:
return {
legalFormats: {
jsonp: true
}
}
The output URL parameter works with JSONP as well.
http://www.cleverna.me/article/My-Clever-Article-Title/page/2/format/jsonp/callback/foo/output/author-email
Returns...
foo("jsmith@cleverna.me")
Do you always want a particular controller action to return JSON without the URL flag? Simple:
async function handler(params) {
// All requests handled by this controller action will output JSON
params.route.format = 'json'
return {
content: {
article: article,
author: author
},
legalFormats: {
json: true
}
}
}
Are you building a RESTful API and want every request across all controllers to return JSON without using the URL flag? Also simple, via optional hooks such as request.js:
// File: /app/hooks/request.js
// All requests will be returned in JSON format because this function runs
// at the beginning of every request. Learn more in the "Application Event Hooks
// and the Context Argument" section.
function start(params) {
// Set the output format to JSON
params.route.format = 'json'
return {
// Set JSON as a legal output format
legalFormats: {
json: true
}
}
}
The JSON output from any controller action is driven by the returned content object. Anything you place in the content object will be present in the JSON output — whether it's present in the HTML view or not.
Take care not to place sensitive data in the content object thinking it will never be exposed because you don't reference it in your view template, because it WILL show up in your JSON.
citizen does a great job of handling unexpected errors without exiting the process (and thereby crashing your server). The following controller action will throw an error, but the server will respond with a 500 and keep running:
async function handler(params, context) {
// app.models.article.foo() throws an error
const foo = await app.models.article.foo()
return {
content: foo
}
}
You can also throw an error manually and customize the error message:
async function handler(params, context) {
// Get the article
const article = await app.models.article.getArticle({
article: params.url.article,
page: params.url.page
})
// If everything is fine, return the content
if ( article ) {
return {
content: article
}
// If there's a problem, throw an error
} else {
let err = new Error('The requested article does not exist.')
// The default error code is 500, but you can specify a different code
err.statusCode = 404
throw err
}
}
Errors are returned in the format requested by the route. If you request JSON and the route throws an error, the error will be in JSON format.
The app skeleton created by the scaffold utility includes optional error view templates for common client and server errors, but you can create templates for any HTTP error code.
To create custom error views for server errors, create a directory called /app/patterns/views/error and populate it with templates named after the HTTP response code or Node error code.
app/
patterns/
views/
error/
404.hbs // Handles 404 errors
500.hbs // Handles 500 errors
ENOENT.hbs // Handles bad file read operations
error.hbs // Handles any error without its own template
These error views are only used when citizen is in production mode. In development mode, citizen dumps the raw error/stack to the view.
In addition to the view content, the controller action's return statement can also pass directives to render alternate views, set cookies and session variables, initiate redirects, call and render includes, cache views (or entire routes), and hand off the request to another controller for further processing.
By default, the server renders the view whose name matches that of the controller. To render a different view, use the view directive in your return statement:
// article controller
module.exports = {
handler: handler
}
async function handler(params, context) {
const article = await app.models.article.getArticle({
article: params.url.article,
page: params.url.page
})
return {
content: article,
// This tells the server to render app/patterns/views/article/edit.hbs
view: 'edit'
}
}
citizen returns HTML by default, and you can enable JSON or JSONP in the global config. However, if you want to enable custom formats at the controller action level, use the legalFormat directive.
If you don't enable a format, either in the controller action or global config, trying to use that format will throw an error.
return {
legalFormat: {
html: false,
json: true,
jsonp: true
}
}
You set cookies by returning a cookie object within the controller action.
Here's an example of a complete cookie object's default settings:
cookie.foo = {
value: 'myValue',
// Valid expiration options are:
// 'now' - deletes an existing cookie
// 'never' - current time plus 30 years, so effectively never
// 'session' - expires at the end of the browser session (default)
// [time in minutes] - expires this many minutes from now
expires: 'session',
// By default, a cookie's path is the same as the app path in your config
path: app.config.citizen.urlPaths.app,
// citizen's cookies are accessible via HTTP only by default. To access a
// cookie via JavaScript, set this to false.
httpOnly: true,
// Cookies are insecure when set over HTTP and secure when set over HTTPS.
// You can override that behavior globally with the https.secureCookies setting
// in your config or on a case-by-case basis with this setting.
secure: false
}
The following sample login controller tells the server to set username and passwordHash cookies that expire in 20 minutes:
// login controller
module.exports = {
handler: handler
}
async function loginForm(params, context) {
let authenticate = await app.models.login.authenticate({
// Form values, just like URL parameters, are passed via the params
// argument
username: params.form.username,
password: params.form.password
}),
// If a directive is an empty object, that's fine. citizen just ignores it.
cookie = {}
if ( authenticate.success ) {
cookie = {
// The cookie gets its name from the property name
username: {
value: authenticate.username,
expires: 20
},
passwordHash: {
value: authenticate.passwordHash,
expires: 20
}
}
}
return {
content: {
authenticate: authenticate
},
cookie: cookie
}
}
Alternatively, you can pass strings into the cookie directive, which will create cookies using the default attributes. The following code sets the same cookies, but they expire at the end of the browser session:
return {
cookie: {
username: authenticate.username,
passwordHash: authenticate.passwordHash
}
}
Cookies sent by the client are available in params.cookie within the controller and simply cookie within the view context:
<!doctype html>
<html>
<body>
<section>
{{#if cookie.username}}
Welcome, {{cookie.username}}.
{{else}}
<a href="/login">Login</a>
{{/if}}
</section>
</body>
</html>
Cookie variables you set within your controller aren't immediately available within the params.cookie scope. citizen has to receive the context from the controller before it can send the cookie to the client, so use a local instance of the variable if you need to access it during the same request.
If you use citizen behind another web server, such as NGINX or Apache, you'll need to add a custom header called x-citizen-uri for secure cookies to work correctly. This is because citizen only has access to the URI it receives in the proxy request, not the actual URI requested by the browser, which in the case of HTTPS requests will have a different protocol.
Here's an example of how you might set this up in NGINX:
location / {
proxy_set_header X-Real-IP $remote_addr
proxy_set_header Host $host
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for
proxy_set_header x-citizen-uri https://website.com$request_uri
proxy_pass http://127.0.0.1:8080
}
If sessions are enabled, you can access session variables via params.session in your controller or simply session within views. These local scopes reference the current user's session without having to pass a session ID.
By default, a session has four properties: id, started, expires, and timer. The session ID is also sent to the client as a cookie called ctzn_sessionID.
Setting session variables is pretty much the same as setting cookie variables:
return {
session: {
username: 'Danny',
nickname: 'Doc'
}
}
Like cookies, session variables you've just assigned aren't available during the same request within the params.session scope, so use a local instance if you need to access this data right away.
Sessions expire based on the sessionTimeout config property, which represents the length of a session in minutes. The default is 20 minutes. The timer is reset with each request from the user. When the timer runs out, the session is deleted. Any client requests after that time will generate a new session ID and send a new session ID cookie to the client.
To forcibly clear and expire the current user's session:
return {
session: {
expires: 'now'
}
}
You can pass redirect instructions to the server that will be initiated after the controller action is processed.
The redirect object takes a URL string in its shorthand version, or three options: statusCode, url, and refresh. If you don't provide a status code, citizen uses 302 (temporary redirect). The refresh option determines whether the redirect uses a Location header or the non-standard Refresh header.
// Initiate a temporary redirect using the Location header
return {
redirect: 'http://cleverna.me/login'
}
// Initiate a permanent redirect using the Refresh header, delaying the redirect
// by 5 seconds
return {
redirect: {
url: 'http://cleverna.me/new-url',
statusCode: 301,
refresh: 5
}
}
Unlike the Location header, if you use the refresh option, citizen will send a rendered view to the client because the redirect occurs client-side.
Using the Location header breaks (in my opinion) the Referer header because the Referer ends up being not the resource that initiated the redirect, but the resource prior to the page that initiated it. To get around this problem, citizen stores a session variable called ctzn_referer that contains the URL of the resource that initiated the redirect, which you can use to redirect users properly. For example, if an unauthenticated user attempts to access a secure page and you redirect them to a login form, the address of the secure page will be stored in ctzn_referer so you can send them there instead of the page containing the link to the secure page.
If you haven't enabled sessions, citizen falls back to creating a cookie named ctzn_referer instead.
If you use citizen behind another web server, such as NGINX or Apache, you'll need to add a custom header called x-citizen-uri for citizen_referer to work correctly. This is because citizen only has access to the URI it receives in the proxy request, not the actual URI requested by the browser. For example, using NGINX as an HTTPS front end means you'll have a different protocol in the requested URI than you'll have in the proxy URI. The x-citizen-uri header ensures citizen receives the original requested URL intact.
Here's an example of how you might set this up in NGINX:
location / {
proxy_set_header X-Real-IP $remote_addr
proxy_set_header Host $host
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for
proxy_set_header x-citizen-uri https://website.com$request_uri
proxy_pass http://127.0.0.1:8080
}
You can set HTTP headers using the header directive:
return {
header: {
'Cache-Control': 'max-age=86400',
'Date': new Date().toISOString()
}
}
citizen lets you use complete MVC patterns as includes. These includes are more than just chunks of code that you can reuse because each has its own controller, model, and view(s). Here's the syntax:
async function handler(params, context) {
return {
include: {
// The include name referenced in your view gets its name from the
// property name. This include calls the _header controller with the
// default action and view.
header: {
controller: '_header'
},
// This include calls the _footer controller using the "myAction" action.
footer: {
controller: '_footer',
action: 'myAction'
},
// This include calls the _login-form controller using the "myAction"
// action and "myView" view.
loginForm: {
controller: '_login-form',
action: 'myAction',
view: 'myView'
},
// This include calls the index controller, but processes it as if it
// had been requested from a different URL. In this case, the include
// will return JSON.
index: {
route: '/index/format/json'
},
// This include calls the index controller, but processes it as if it
// had been requested from a different URL and uses an alternate view.
index: {
route: '/index/format/json',
view: 'myView'
}
}
}
}
Let's say our article pattern's template has the following contents. The head section contains dynamic meta data, and the header's content changes depending on whether the user is logged in or not:
<!doctype html>
<html>
<head>
<title>{{metaData.title}}</title>
<meta name="description" content="{{metaData.description}}">
<meta name="keywords" content="{{metaData.keywords}}">
<link rel="stylesheet" type="text/css" href="site.css">
</head>
<body>
<header>
{{#if cookie.username}}
<p>Welcome, {{cookie.username}}</p>
{{else}}
<a href="/login">Login</a>
{{/if}}
</header>
<main>
<h1>{{title}} — Page {{url.page}}</h1>
<p>{{summary}}</p>
<section>{{text}}</section>
</main>
</body>
</html>
It probably makes sense to use includes for the head section and header because you'll use that code everywhere, but rather than simple partials, you can create citizen includes. The head section can use its own model for populating the meta data, and since the header is different for authenticated users, let's pull that logic out of the view and put it in the header's controller. I like to follow the convention of starting partials with an underscore, but that's up to you:
app/
patterns/
controllers/
_head.js
_header.js // Doesn't pull data, so it doesn't need a model
article.js
models/
_head.js
article.js
views/
_head/
_head.hbs
_header/
_header.hbs
_header-authenticated.hbs // A different header for logged in users
article/
article.hbs
When the article controller is fired, it has to tell citizen which includes it needs. We do that with the include directive:
// article controller
module.exports = {
handler: handler
}
async function handler(params, context) {
// Get the article
const article = await app.models.article.getArticle({
article: params.url.article,
page: params.url.page
})
return {
content: article,
include: {
head: {
// If only the controller is specified, the default action handler() is
// called and the default view is rendered (_head.hbs in this case).
controller: '_head'
},
header: {
controller: '_header',
// If the username cookie exists, use the authenticated action. If not,
// use handler.
action: params.cookie.username ? 'authenticated' : 'handler'
// You can also specify the view here like this:
// view: '_header-authenticated'
// But we'll do that in the header controller instead. If you do specify
// a view here, it will override whatever view is set in the controller.
}
}
}
}
citizen include patterns have the same requirements as regular patterns, including a controller with a public action. The include directive above tells citizen to call the _head and _header controllers, pass them the same arguments that were passed to the article controller (params and context), render their respective views, and add the resulting views to the view context.
Here's what our head section controller might look like:
// _head controller
module.exports = {
handler: handler
}
async function handler(params, context) {
let metaData = await app.models._head({ article: params.url.article })
return {
content: metaData
}
}
And the head section view:
<head>
<title>{{title}}</title>
<meta name="description" content="{{description}}">
<meta name="keywords" content="{{keywords}}">
<link rel="stylesheet" type="text/css" href="site.css">
</head>
Here's what our header controller might look like:
// _header controller
module.exports = {
handler: handler,
authenticated: authenticated
}
function handler(params, context) {
return {
view: '_header'
}
}
function authenticated(params, context) {
return {
view: '_header-authenticated'
}
}
And the header views:
{{! _header view (/patterns/views/_header/_header.hbs) }}
<header>
<a href="/login">Login</a>
</header>
{{! _header-authenticated view (/patterns/views/_header/_header-authenticated.hbs) }}
<header>
<p>Welcome, {{cookie.username}}</p>
</header>
The rendered includes are stored in the include scope. The include object contains rendered HTML views, so you need to skip escaping ({{{...}}} in Handlebars) within the article view:
{{! article.hbs }}
<!doctype html>
<html>
{{{include.head}}}
<body>
{{{include.header}}}
<main>
<h1>{{title}} — Page {{url.page}}</h1>
<p>{{summary}}</p>
<section>{{text}}</section>
</main>
</body>
</html>
citizen includes are self-contained. While they receive the same request context (URL parameters, form inputs, etc.) as the calling controller, content generated by the calling controller isn't automatically passed to its includes, and content generated inside an include isn't passed back to the caller. citizen includes also can't make use of cookie, session, redirect, or handoff directives, nor can they use their own includes (nested includes). Any of these directives within an include will be ignored. They only use the content directive (to populate their own views), the view directive for setting the view used by the include, and the cache directive for controller caching.
A pattern meant to be used as an include can be accessed via HTTP just like any other controller. You could request the _head controller like so:
http://cleverna.me/_head
Perhaps you'd have it return meta data as JSON for the article pattern:
// http://cleverna.me/_head/article/My-Clever-Article-Title/format/json
{
"title": "My Clever Article Title",
"description": "My article's description.",
"keywords": "clever, article, keywords"
}
Of course, if you don't write the controller in a manner to accept direct requests and return content, it'll return nothing (or throw an error). When accessed via HTTP, the controller has access to all controller directives.
Reminder: To make a controller private — inaccessible via HTTP, but accessible within your app — add a plus sign (+) to the beginning of the file name:
app/
patterns/
controllers/
+_header.js // Only accessible internally
_head.js // Accessible via www.cleverna.me/_head
article.js // Accessible via www.cleverna.me/article
citizen includes provide rich functionality, but they do have limitations and can be overkill in certain situations.
citizen allows the requested controller to give another controller the responsibility of handling the request and rendering its own view via a directive called handoff. The requested controller passes its content and directives to a secondary controller that assumes responsibility for the request, adding its own content and directives and rendering its own view. This is also a method for passing your own custom content and directives to the receiving controller.
A common use case for handoff would be to create a layout controller that serves as a template for every page on your site, rendering all the includes necessary and leaving only the core content and markup to the initially requested controller. Let's modify the article controller and view so it hands off rendering responsibility to a separate layout controller:
// article controller
module.exports = {
handler: handler
}
async function handler(params, context) {
const article = await app.models.article.getArticle({
article: params.url.article,
page: params.url.page
})
return {
content: article,
handoff: {
// Pass this request to app/patterns/controller/+_layout.js
controller: '+_layout',
// Specifying the action is optional. The layout controller will use its
// default action, handler(), unless you specify a different action here.
action: 'handler',
// Specifying the view is optional. The layout controller will use its
// default view unless you tell it to use a different one.
view: '+_layout'
},
// A custom directive to drive some logic in the layout controller.
// You could even pass a function here for layout to call.
// Just don't use any reserved citizen directive names.
myDirective: {
doSomething: true
}
}
}
The view of the originally requested controller (article.hbs in this case) is rendered and stored in the route.chain object:
{{! article.hbs, which is stored in the route.chain scope }}
<h1>{{title}}</h1>
<p>{{summary}}</p>
<section>{{text}}</section>
The layout controller handles the includes, follows your custom directive, and renders its own view:
// layout controller
module.exports = {
handler: handler
}
async function handler(params, context) {
// Access my custom directive using the context argument
if ( context.myDirective && context.myDirective.doSomething ) {
await doSomething()
}
return {
// No need to specify previous directives here, such as content, because
// citizen keeps track of the article pattern's request context throughout
// the handoff process.
include: {
head: {
controller: '_head'
},
header: {
controller: '_header',
action: params.cookie.username ? 'authenticated' : 'handler'
}
}
}
}
async function doSomething() {
// do something
}
You can use handoff to chain requests across as many controllers as you want, with each controller's directives added to the request context. All controllers in the chain are stored in the route object as an array called route.chain:
[
{ controller: 'article',
action: 'handler',
view: 'article',
viewContent: '<h1>My Article Title</h1><p>The article summary.</p><section>The article text.</section>'
},
{ controller: '+_layout',
action: 'handler',
view: '+_layout'
}
]
You can loop over this object to render all the chained views:
{{! +_layout.hbs }}
<!doctype html>
<html>
{{{include.head}}}
<body>
{{{include.header}}}
<main>
{{! Loop over each controller in the chain and incorporate its rendered view }}
{{#each route.chain}}
{{viewContent}}
{{/each}}
</main>
</body>
</html>
It's assumed the last controller in the chain provides the master view, so it has no viewContent; that's what the server sends to the client.
You can skip rendering a controller's view in the handoff chain by setting view to false:
// article controller
return {
// Don't render the article controller's view as part of the chain
view: false,
handoff: {
controller: 'next-controller'
}
}
As mentioned in the config section at the beginning of this document, you can specify a default layout controller in your config so you don't have to specify it in every controller:
{
"citizen": {
"layout": {
"controller": "+_layout",
"view": "+_layout"
}
}
}
If you use this method, there's no need to use handoff for the layout.
citizen provides several ways for you to improve your app's performance, most of which come at the cost of system resources (memory or CPU). You'll definitely want to do some performance monitoring to make sure the benefits are worth the cost.
Both dynamic routes and static assets can be compressed before sending them to the browser. To enable compression for clients that support it:
{
"citizen": {
"compression": {
"enable": true
}
}
}
Proxies, firewalls, and other network circumstances can strip the request header that tells the server to provide compressed assets. You can force gzip or deflate for all clients like this:
{
"citizen": {
"compression": {
"enable": true,
"force": "gzip"
}
}
}
If you have route caching enabled, both the original and compressed versions of the route will be cached, so your cache's memory utilization will increase.
In many cases, a requested route or controller will generate the same view every time based on the same input parameters, so it doesn't make sense to run the controller chain and render the view from scratch for each request. citizen provides flexible caching capabilities to speed up your server side rendering via the cache directive.
If a given route (URL) will result in the exact same rendered view with every request, you can cache that view with the route attribute. This is the fastest cache option because it pulls a fully rendered view from memory and skips all controller processing.
Let's say you chain the article controller with the layout controller like we did above. If you put the following cache directive in your controller action, the requested route's view will be cached and subsequent requests will skip the article and layout controllers entirely.
return {
handoff: {
controller: '+_layout'
},
cache: {
route: true
}
}
Each of the following routes would generate its own cache item:
http://cleverna.me/article/My-Article
http://cleverna.me/article/My-Article/page/2
Note that if you put the cache.route directive anywhere in your controller chain, the route will be cached.
The example above is shorthand for default cache settings. The cache.route directive can also be an object with options:
// Cache the requested route with some additional options
return {
cache: {
route: {
// Optional. This setting lets the server respond with a 304 Not Modified
// status if the cache content hasn't been updated since the client last
// accessed the route. Defaults to the current time if not specified.
lastModified: new Date().toISOString(),
// Optional. List of valid URL parameters that protects against accidental
// caching of malformed URLs.
urlParams: ['article', 'page'],
// Optional. Life of cached item in minutes. Default is 15 minutes.
// For no expiration, set to 'application'.
lifespan: 30,
// Optional. Reset the cached item's expiration timer whenever the item is
// accessed, keeping it in the cache until traffic subsides.
resetOnAccess: true
}
}
}
If a given route chain will vary across requests, you can still cache individual controllers to speed up rendering. The controller property tells citizen to cache the controller, while the scope option determines how the controller and its resulting view are cached.
// Cache this controller using the default settings
return {
handoff: {
controller: '+_layout'
},
cache: {
controller: true
}
}
// Cache this controller with additional options
return {
cache: {
controller: {
// Optional. If caching the controller, 'global' (default) will cache one
// instance of the controller and use it globally, while 'route' will cache
// a unique instance of the controller for every route that calls it.
scope: 'route',
// Optional. List of directives to cache with the controller.
directives: ['handoff', 'cookie'],
// These options function the same as in route caching (see above)
urlParams: ['article', 'page'],
lifespan: 15,
resetOnAccess: true
}
}
}
lastModified (route cache only)This setting lets the server respond with a faster 304 Not Modified response if the content of the route cache hasn't changed since the client last accessed it. By default, it's set to the time at which the route was cached, but you can specify a custom date in ISO format that reflects the last modification to the route's content. This way, if you restart your app or clear the cache for some reason, returning clients will still get a 304.
return {
handoff: {
controller: '+_layout'
},
cache: {
route: {
// Use toISOString() to format your date appropriately
lastModified: myDate.toISOString() // 2015-03-05T08:59:51.491Z
}
}
}
urlParamsThe urlParams property helps protect against invalid cache items (or worse: an attack meant to flood your server's resources by overloading the cache).
return {
handoff: {
controller: '+_layout'
},
cache: {
route: {
urlParams: ['article', 'page']
}
}
}
If we used the example above in our article controller, the following URLs would be cached because the "article" and "page" URL parameters are permitted:
http://cleverna.me/article/My-Article-Title
http://cleverna.me/article/My-Article-Title/page/2
The following URLs wouldn't be cached, which is a good thing because it wouldn't take long for an attacker's script to loop over a URL and flood the cache:
http://cleverna.me/article/My-Article-Title/dosattack/1
http://cleverna.me/article/My-Article-Title/dosattack/2
http://cleverna.me/article/My-Article-Title/page/2/dosattack/3
The server logs an error when invalid URL parameters are present, but continues processing without caching the result.
directives (controller cache only)By default, any directives you specify in a cached controller aren't cached; they're implemented the first time the controller is called and then ignored after that. This is to prevent accidental storage of private data in the cache through session or cookie directives.
If you want directives to persist within the cache, include them in the directives property as an array:
return {
handoff: {
controller: '+_layout'
},
cookie: {
myCookie: {
value: 'howdy',
expires: 'never'
}
},
myCustomDirective: {
doSomething: true
},
cache: {
controller: {
scope: 'route',
// Cache handoff and myCustomDirective so that if this controller is
// called from the cache, it hands off to the layout controller and acts
// upon myCustomDirective every time. The cookie directive will only be
// acted upon the first time the controller is called, however.
directives: ['handoff', 'myCustomDirective']
}
}
}
lifespanThis setting determines how long the route or controller should remain in the cache, in minutes.
return {
cache: {
route: {
// This route cache will expire in 10 minutes
lifespan: 10
}
}
}
resetOnAccessUsed with the lifespan setting, resetOnAccess will reset the timer of the route or controller cache whenever it's accessed, keeping it in the cache until traffic subsides.
return {
cache: {
route: {
// This route cache will expire in 10 minutes, but if a request accesses it
// before then, the cache timer will be reset to 10 minutes from now
lifespan: 10,
resetOnAccess: true
}
}
}
As mentioned previously, if you use the handoff directive to call a series of controllers and any one of those controllers sets cache.route to true, the final view will be cached. Therefore, caching any controllers in that chain might be redundant. In most cases, you'll want to choose between caching an entire route or caching individual controllers, but not both.
When caching an include controller, the view directive doesn't work. Set the view within the include directive of the calling controller.
citizen's cache is a RAM cache stored in the V8 heap, so be careful with your caching strategy. Use the lifespan and resetOnAccess options so URLs that receive a lot of traffic stay in the cache, while less popular URLs naturally fall out of the cache over time.
By caching static assets in memory, you speed up file serving considerably. To enable static asset caching for your app's public (web) directory, set "static" to true in your config:
{
"citizen": {
"cache": {
"static": {
"enable": true
}
}
}
}
With static caching enabled, all static files citizen serves will be cached in the V8 heap, so keep an eye on your app's memory usage to make sure you're not using too many resources. citizen handles all the caching and response headers (ETags, 304 status codes, etc.) for you using each file's modified date. Note that if a file changes after it's been cached, you'll need to clear the file cache using cache.clear() or restart the app.
To clear a file from the cache in a running app:
app.cache.clear({ file: '/absolute/path/to/file.jpg' })
citizen automatically sets ETag headers for cached routes and static assets. You don't need to do anything to make them work. The Cache-Control header is entirely manual, however.
To set the Cache-Control header for static assets, use the citizen.cache.control setting in your config:
{
"citizen": {
"cache": {
"static": true,
"control": {
"/css/global.css": "max-age=86400",
"/css/index.css": "max-age=86400",
"/js/global.js": "max-age=86400",
"/js/index.js": "max-age=86400",
"/images/logo.png": "max-age=31536000"
}
}
}
}
The key name is the pathname that points to the static asset in your web directory. If your app's URL path is /my/app, then this value should be something like /my/app/styles.css. The value is the Cache-Control header value you want to assign to that asset.
You can use strings that match the exact pathname like above, or you can also use regular expressions. Mixing the two is fine:
{
"citizen": {
"cache": {
"static": true,
"control": {
"/css/*": "max-age=86400",
"/js/*": "max-age=86400",
"/images/logo.png": "max-age=31536000"
}
}
}
}
Here's a great tutorial on client-side caching to help explain ETag and Cache-Control headers.
citizen uses formidable to parse form data. When a user submits a form, the resulting form data is available in your controller via params.form.
// login controller
function handler(params, context) {
// Set some defaults for the login view
params.form.username = ''
params.form.password = ''
params.form.remember = false
}
// Using a separate action in your controller for form submissions
// is probably a good idea
async function form(params, context) {
let authenticate = await app.models.user.authenticate({
username: params.form.username,
password: params.form.password
}),
cookie = {}
if ( authenticate.success ) {
if ( params.form.remember ) {
cookie.username: params.form.username
}
return {
cookie: cookie,
redirect: '/'
}
} else {
return {
content: {
message: 'Login failed.'
}
}
}
}
If it's a multipart form containing a file, the form object passed to your controller will look something like this:
{
foo: 'bar',
fizz: 'buzz',
fileFieldName: {
size: 280,
path: '/tmp/upload_6d9c4e3121f244abdff36311a3b19a16',
name: 'image.png',
type: 'image/png',
hash: null,
lastModifiedDate: Fri Feb 27 2015 06:01:36 GMT-0500 (EST)
}
}
See the formidable documentation for available form settings. You can pass global form settings via citizen.form in the config or at the controller action level via controller config (see below).
The following config sets the upload directory for all forms to the path specified. It also sets the maxFieldsSize setting for the editForm() action in the article controller to 500k:
{
"citizen": {
"form": {
"uploadDir": '/absolute/path/to/upload/directory',
"maxFieldsSize": 500
}
}
}
Unlike formidable, the maxFieldsSize option includes images in a multipart form in its calculations. citizen includes this enhancement because formidable provides no built-in way of limiting file upload sizes.
You can also set options for individual form actions within controllers using the config export. These settings extend and override the global form settings.
// login controller
module.exports = {
config: {
form: {
// Options for the loginForm() controller action
loginForm: {
maxFieldsSize: 1000
}
}
}
}
citizen makes it easy to build progressively enhanced HTML forms that work both server-side and client-side. Here's a login form that will submit to the login controller and fire the form() action:
<section class="login-form">
<p id="message">
{{#if message}}
{{message}}
{{else}}
Please log in below.
{{/if}}
</p>
<form id="login-form" action="/login/action/form" method="post" novalidate>
<section class="data">
<ul>
<li>
<label for="username">Username</label>
<input id="username" name="username" value="{{form.username}}" required autofocus>
</li>
<li>
<label for="password">Password</label>
<input id="password" name="password" value="{{form.password}}" required>
</li>
</ul>
</section>
<section class="actions">
<input name="submit" type="submit" value="Sign in">
</section>
</form>
</section>
This will perform a traditional POST to the server and reload the login page to display any messages. You can easily enhance this with a little JavaScript on the client to submit via AJAX and return a JSON response:
var loginForm = document.querySelector('#login-form'),
message = document.querySelector('#message')
loginForm.addEventListener('submit', function (e) {
var request = new XMLHttpRequest(),
formData = new FormData(loginForm)
e.preventDefault()
// Appending /format/json to the form action tells the server to
// respond with JSON instead of a rendered HTML view
request.open(loginForm.method, loginForm.action + '/format/json', true)
request.send(formData)
request.onload = function() {
var loginResponse = JSON.parse(request.responseText)
message.innerHTML = loginResponse.message
}
})
By appending /format/json to the action URL via JavaScript, we receive a JSON response from the controller and can then parse this response and update the view on the client. This is a form that provides a good user experience, but still works without JavaScript.
Certain events will occur throughout the life of your citizen application. You can act on these application events, execute functions, set directives, and pass the results to the next event or your controller via the context argument. For example, you might set a custom cookie at the beginning of every new session, or check for cookies at the beginning of every request and redirect the user to a login page if they're not authenticated.
To take advantage of these events, include a directory called "hooks" in your app with any or all of following modules and exports:
app/
hooks/
application.js // exports start() and error()
request.js // exports start() and end()
response.js // exports start() and end()
session.js // exports start() and end()
request.start(), request.end(), and response.start() are called before your controller is fired, so the output from those events is passed from each one to the next, and ultimately to your controller via the context argument. Exactly what they output—content, citizen directives, custom directives—is up to you.
All files and exports are optional. citizen parses them at app start and only calls them if they exist. For example, you could have only a request.js module that exports start().
Here's an example of a request module that checks for a username cookie at the beginning of every request and redirects the user to the login page if it doesn't exist. We also avoid a redirect loop by making sure the requested controller isn't the login controller:
// app/hooks/request.js
module.exports = {
start: start
}
function start(params, context) {
let redirect = {}
if ( !params.cookie.username && params.route.controller !== 'login' ) {
redirect = '/login'
}
return {
redirect: redirect
}
}
session.end is slightly different in terms of the arguments in receives, which consist of a copy of the expired session (no longer active) and any context passed from citizen:
// app/hooks/session.js
module.exports = {
end: end
}
function end(expiredSession, context) {
// do something whenever a session ends
}
By default, all controllers respond to requests from the host only. citizen supports cross-domain HTTP requests via access control headers.
To enable cross-domain access for individual controller actions, add a cors object with the necessary headers to your controller's exports:
module.exports = {
handler: handler,
cors: {
// Each controller action has its own CORS headers
handler: {
'Access-Control-Allow-Origin': 'http://www.foreignhost.com',
'Access-Control-Expose-Headers': 'X-My-Custom-Header, X-Another-Custom-Header',
'Access-Control-Max-Age': 600,
'Access-Control-Allow-Credentials': 'true',
'Access-Control-Allow-Methods': 'OPTIONS, PUT',
'Access-Control-Allow-Headers': 'Content-Type',
'Vary': 'Origin'
}
}
}
Why not just use the HTTP Headers directive within the controller action itself? When citizen receives a request from an origin other than the host, it checks for the cors export in your controller to provide a preflight response, skipping controller processing entirely for improved performance and no logic required on your part.
For more details on CORS, check out the W3C spec and the Mozilla Developer Network.
citizen has helper functions that it uses internally, but might be of use to you, so it returns them for public use.
You can store any object in citizen's cache. The primary benefits of using cache() over storing content in your own global app variables are built-in cache expiration and extension, as well as wrappers for reading, parsing, and storing file content.
citizen's default cache time is 15 minutes, which you can change in the config (see Configuration). Cached item lifespans are extended whenever they are accessed unless you pass resetOnAccess: false or change that setting in the config.
// Cache a string in the default app scope for 15 minutes (default). Keys
// must be unique within a given scope.
app.cache.set({
key: 'welcome-message',
value: 'Welcome to my site.'
})
// Cache a string under a custom scope, which is used for retrieving or clearing
// multiple cache items at once. Keys must be unique within a given scope.
// Reserved scope names are "app", "controllers", "routes", and "files".
app.cache.set({
key: 'welcome-message',
scope: 'site-messages',
value: 'Welcome to our site.'
})
// Cache a string for the life of the application.
app.cache.set({
key: 'welcome-message',
value: 'Welcome to my site.',
lifespan: 'application'
})
// Cache a string for the life of the application, and overwrite the
// existing key. The overwrite property is required any time you want to
// write to an existing key. This prevents accidental overwrites.
app.cache.set({
key: 'welcome-message',
value: 'Welcome to our site.',
lifespan: 'application',
overwrite: true
})
// Cache a file buffer using the file path as the key. This is a wrapper for
// fs.readFile and fs.readFileSync paired with citizen's cache function.
// Optionally, tell citizen to perform a synchronous file read operation and
// use an encoding different from the default (UTF-8).
app.cache.set({
file: '/path/to/articles.txt',
synchronous: true,
encoding: 'CP-1252'
})
// Cache a file with a custom key. Optionally, parse the JSON and store the
// parsed object in the cache instead of the raw buffer. Expire the cache
// after 10 minutes, regardless of whether the cache is accessed or not.
app.cache.set({
file: '/path/to/articles.json',
key: 'articles',
parseJSON: true,
lifespan: 10,
resetOnAccess: false
})
app, controllers, routes, and files are reserved scope names, so you can't use them for your own custom scopes.
This is a way to check for the existence of a given key or scope in the cache without resetting the cache timer on that item. Returns false if a match isn't found.
// Check for the existence of the specified key
var keyExists = app.cache.exists({ key: 'welcome-message' }) // keyExists is true
var keyExists = app.cache.exists({ file: '/path/to/articles.txt' }) // keyExists is true
var keyExists = app.cache.exists({ file: 'articles' }) // keyExists is true
var keyExists = app.cache.exists({ key: 'foo' }) // keyExists is false
// Check the specified scope for the specified key
var keyExists = app.cache.exists({
scope: 'site-messages',
key: 'welcome-message'
})
// keyExists is true
// Check if the specified scope exists and contains items
var scopeExists = app.cache.exists({
scope: 'site-messages'
})
// scopeExists is true
// Check if the controller cache has any instances of the specified controller
var controllerExists = app.cache.exists({
controller: 'article'
})
// Check if the controller cache has any instances of the specified controller
// and action
var controllerExists = app.cache.exists({
controller: 'article',
action: 'edit'
})
// Check if the controller cache has any instances of the specified controller,
// action, and view
var controllerExists = app.cache.exists({
controller: 'article',
action: 'edit',
view: 'edit'
})
// Check if the controller cache has an instance of the specified controller,
// action, and view for a given route
var controllerExists = app.cache.exists({
controller: 'article',
action: 'edit',
view: 'edit',
route: '/article/My-Article/page/2'
})
Retrieve an individual key or an entire scope. Returns false if the requested item doesn't exist. If resetOnAccess was true when the item was cached, using retrieve() will reset the cache clock and extend the life of the cached item. If a scope is retrieved, all items in that scope will have their cache timers reset.
Optionally, you can override the resetOnAccess attribute when retrieving a cache item by specifying it inline.
// Retrieve the specified key from the default (app) scope
var welcomeMessage = app.cache.get({
key: 'welcome-message'
})
// Retrieve the specified key from the specified scope and reset its cache timer
// even if resetOnAccess was initially set to false when it was stored
var welcomeMessage = app.cache.get({
scope: 'site-messages',
key: 'welcome-message',
resetOnAccess: true
})
// Retrieve all keys from the specified scope
var siteMessages = app.cache.get({
scope: 'site-messages'
})
// Retrieve a cached file
var articles = app.cache.get({
file: '/path/to/articles.txt'
})
// Retrieve a cached file with its custom key
var articles = app.cache.get({
file: 'articles'
})
Clear a cache object using a key or a scope.
// Store some cache items
app.cache.set({
key: 'welcome-message',
scope: 'site-messages',
value: 'Welcome to our site.'
})
app.cache.set({
key: 'goodbye-message',
scope: 'site-messages',
value: 'Thanks for visiting!'
})
app.cache.set({
file: '/path/to/articles.txt',
synchronous: true
})
// Clear the welcome message from its custom scope cache
app.cache.clear({ scope: 'site-messages', key: 'welcome-message' })
// Clear all messages from the cache using their custom scope
app.cache.clear({ scope: 'site-messages' })
// Clear the articles cache from the file scope
app.cache.clear({ file: '/path/to/articles.txt' })
clear() can also be used to remove cached routes and controllers from their respective caches.
// Clear the specified route from the cache
app.cache.clear({
route: '/article/My-Article/page/2/action/edit'
})
// Clear the specified controller from the cache, including all actions and views
app.cache.clear({
controller: 'article'
})
// Clear the specified controller/action pairing from the cache. All cached views
// related to this pairing will be deleted.
app.cache.clear({
controller: 'article',
action: 'edit'
})
// Clear the specified controller/action/view combination from the cache
app.cache.clear({
controller: 'article',
action: 'edit',
view: 'edit'
})
// Clear the specified controller/action/view/route combination from the cache
app.cache.clear({
controller: 'article',
action: 'edit',
view: 'edit',
route: '/article/My-Article/page/2/action/edit'
})
// Clear the entire controller scope
app.cache.clear({ scope: 'controllers' })
// Clear the entire route scope
app.cache.clear({ scope: 'routes' })
// Clear the entire file scope
app.cache.clear({ scope: 'files' })
// Clear the entire app scope
app.cache.clear({ scope: 'app' })
Makes it easy to log comments to either the console or a file (or both) in a way that's dependent on the mode of the framework.
When citizen is in production mode, log() does nothing by default. In development mode, log() will log whatever you pass to it. This means you can place it throughout your application's code and it will only write to the log in development mode. You can override this behavior globally with the log settings in your config file or inline with the console or file options when calling log().
app.log({
// Optional. Valid settings are "status" (default) or "error".
type: 'error',
// Optional string. Applies a label to your log item.
label: 'Log output',
// The content of your log. If it's anything other than a string or
// number, log() will run util.inspect on it and dump the contents.
contents: someObject,
// Optional. By default, log() uses the config.citizen.log.console setting
// to determine whether to log to the console, but this option overrides it.
console: false,
// Optional. By default, log() uses the config.citizen.log.file setting
// to determine whether to log to a file, but this option overrides it.
file: false,
// Optional. By default, log() uses "citizen.log" as the file name for your logs.
// Use this option to override the default inline.
file: 'my-log-file.log',
// Optional. Disables the timestamp that normally appears in front of the log
timestamp: false
})
Log files appear in the folder you specify in config.citizen.directories.logs.
Warning: development mode is inherently insecure. Don't use it in a production environment.
If you set "mode": "development" in your config file, citizen dumps the current pattern's context and request parameters to the console. You can dump it to the view instead by setting development.debug.view in your config file to true, or use the ctzn_dump URL parameter on a per-request basis:
// config file: always dumps debug output in the view
{
"citizen": {
"development": {
"debug": {
"view": true
}
}
}
}
By default, the pattern's complete output is dumped. You can specify the exact object to debug with the ctzn_debug URL parameter. You can access globals, pattern (which is the current controller chain), and request params:
// Dumps pattern.content
http://www.cleverna.me/article/id/237/page/2/ctzn_debug/pattern.content
// Dumps the server params object
http://www.cleverna.me/article/id/237/page/2/ctzn_debug/params
// Dumps the user's session scope
http://www.cleverna.me/article/id/237/page/2/ctzn_debug/params.session
// Dumps the user's session scope to the view
http://www.cleverna.me/article/id/237/page/2/ctzn_debug/params.session/ctzn_dump/view
The debug output traverses objects 3 levels deep by default. To display deeper output, use the development.debug.depth setting in your config file or append ctzn_debugDepth to the URL. Debug rendering will take longer the deeper you go.
// config file: debug 4 levels deep
{
"citizen": {
"development": {
"debug": {
"depth": 4
}
}
}
}
// URL
http://www.cleverna.me/article/id/237/page/2/ctzn_debugDepth/4
In development mode, you must specify the ctzn_debug URL parameter to display debug output. Debug output is disabled in production mode.
The util directory within the citizen package has some helpful utilities.
Creates a complete skeleton of a citizen app with a functional index pattern and error templates.
$ node node_modules/citizen/util/scaffold skeleton
Resulting file structure:
app/
config/
citizen.json
logs/
hooks/
application.js
request.js
response.js
session.js
patterns/
controllers/
index.js
models/
index.js
views/
error/
404.hbs
500.hbs
ENOENT.hbs
error.hbs
index/
index.hbs
start.js
web/
Run node node_modules/citizen/util/scaffold skeleton -h for options.
Creates a complete citizen MVC pattern. The pattern command takes a pattern name and options:
$ node node_modules/citizen/util/scaffold pattern [options] [pattern]
For example, node scaffold pattern article will create the following pattern:
app/
patterns/
controllers/
article.js
models/
article.js
views/
article/
article.hbs
Use node node_modules/citizen/util/scaffold pattern -h to see all available options for customizing your patterns.
(The MIT License)
Copyright (c) 2014-2019 Jay Sylvester
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
FAQs
Node.js MVC web application framework. Includes routing, serving, caching, session management, and other helpful tools.
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