express-promise
An express.js middleware for easy rendering async query.
Cases
1. previously
app.get('/users/:userId', function(req, res) {
User.find(req.params.userId).then(function(user) {
Project.getMemo(req.params.userId).then(function(memo) {
res.json({
user: user,
memo: memo
});
});
});
});
1. now
app.get('/users/:userId', function(req, res) {
res.json({
user: User.find(req.params.userId),
memo: Project.getMemo(req.params.userId)
});
});
2. previously
app.get('/project/:projectId', function(req, res) {
var field = req.query.fields.split(';');
var result = {};
var pending = 0;
if (field.indexOf('people') !== -1) {
pending++;
Project.getField(req.params.projectId).then(function(result) {
result.people = result;
if (--pending) {
output();
}
});
}
if (field.indexOf('tasks') !== -1) {
pending++;
Project.getTaskCount(req.params.projectId).then(function(result) {
result.tasksCount= result;
if (--pending) {
output();
}
});
}
function output() {
res.json(result);
}
});
2. now
app.get('/project/:projectId', function(req, res) {
var field = req.query.fields.split(';');
var result = {};
if (field.indexOf('people') !== -1) {
result.people = Project.getField(req.params.projectId);
}
if (field.indexOf('tasks') !== -1) {
result.tasksCount = Project.getTaskCount(req.params.projectId);
}
res.json(result);
});
Install
$ npm install express-promise
Usage
Just app.use
it!
app.use(require('express-promise')());
This library supports the following methods: res.send
, res.json
, res.render
.
If you want to let express-promise support nodejs-style callbacks, you can use dotQ to convert the nodejs-style callbacks to Promises. For example:
require('dotq');
app.use(require('express-promise')());
var fs = require('fs');
app.get('/file', function(req, res) {
res.send(fs.readFile.promise(__dirname + '/package.json', 'utf-8'));
});
Libraries
express-promise works well with some ODM/ORM libraries such as Mongoose and Sequelize. There are some examples in the /examples folder.
Mongoose
When query a document without passing a callback function, Mongoose will return a Query instance. For example:
var Person = mongoose.model('Person', yourSchema);
var query = Person.findOne({ 'name.last': 'Ghost' }, 'name occupation');
Query has a exec
method, when you call query.exec(function(err, result) {})
, the query will execute and the result will return to the callback function. In some aspects, Query is like Promise, so express-promise supports Query as well. You can do this:
exports.index = function(req, res){
res.render('index', {
title: 'Express',
cat: Cat.findOne({name: 'Zildjian'})
});
};
and in the index.jade, you can use cat
directly:
p The name of the cat is #{cat.name}
Sequelize
Sequelize supports Promise after version 1.7.0 :)
Articles and Recipes
License
The MIT License (MIT)
Copyright (c) 2013 Zihua Li
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.