mccracken

McCracken

A JSON API client for Ruby

Installation

Add this line to your application's Gemfile:

gem 'mccracken'

And then execute:

$ bundle

Or install it yourself as:

$ gem install mccracken

Basic Usage

class Article < McCracken::Resource
  # This is done automatically if the tableize method is present
  self.type = :articles

  # how to process the JSON API ID. JSON API always uses strings, but McCracken defaults to :integer
  key_type :integer, #:string, ->(id){ }
  attribute :title, :string
end

Registering the JSONAPI 'type'

Calling Article.type = :articles registers the class Article as the handler for JSON API resources of the type articles.

When the ActiveSupport method tableize is present, this will be set automatically. A class can be bound to multiple types:

Article.type = :articles
McCracken.register_type(:posts, Article)

Querying

articles = Article.fetch # Get some articles
article = Article.find(9) # Find an article

query = Article.fields(:title).include(:author, :comments).sort(id: :desc).filter(published: true)
query.to_params #=> {:filter=>{:published=>"true"}, :fields=>{:articles=>"title"}, :include=>"author,comments", :sort=>"-id"}
query.to_query_string #=> "fields[articles]=title&filter[published]=true&include=author,comments&sort=-id"

query.fetch # Fetch articles w/ the given query string

The McCracken::Resource delegates a few methods to its underlying McCracken::Connection:

Filtering

query = Product.filter(min_price: 30, max_price: 65)

# its chainable
query.filter(category: 'Hats').filter(size: ['small', 'medium'])

query.to_params
#=> {:filter=>{:min_price=>"30", :max_price=>"65", :category=>"Hats", :size=>"small,medium"}}

query.fetch #=> McCracken::Collection<Product,Product>

Sorting

query = Product.sort(created_at: :desc)

# its chainable
query.sort(:price) # defaults to ASC

query.to_params
#=> {:sort=>"-created_at,price"}

query.fetch #=> McCracken::Collection<Product,Product>

Including (Side loading related resources)

query = Product.include(:manufacturer)

# its chainable
query.include(:vendor)

query.to_params
#=> {:include=>"manufacturer,vendor"}

query.fetch #=> McCracken::Collection<Product,Product>

Sparse Fieldsets

query = Product.fields(products: [:name, :price])

# its chainable
query.include(:manufacturer).fields(manufacturer: [:name])

query.to_params
#=> {:fields=>{:products=>"name,price", :manufacturer=>"name"}, :include=>"manufacturer"}

query.fetch #=> McCracken::Collection<Product,Product>

All the things!

query = Product.
  filter(min_price: 30, max_price: 65).
  includes(:manufacturer).
  sort(popularity: :desc, price: :asc).
  fields(product: ['name', 'price'], manufacturer: ['name', 'website']).
  page(number: 1, limit: 100)

query.to_params

#=> {:filter=>{:min_price=>"30", :max_price=>"65"}, :fields=>{:product=>"name,price", :manufacturer=>"name,website"}, :include=>"manufacturer", :sort=>"-popularity,price", :page=>{:limit=>10}}

query.fetch #=> McCracken::Collection<Product,Product>

Fetching a single resource

Product.find(1) #=> product

Accessing McCracken internals

Every McCracken::Resource has an internally managed client. It is accessible via .mccracken

Article.mccracken #=> McCracken::Client
Article.mccracken.path #=> base path to use for this resource. Defaults to "/" + type; i.e., "/articles"
Article.mccracken.agent #=> McCracken::Agent: the agent wraps the McCracken::Connection. It performs the low level GET/POST/PUT/PATCH/DELETE methods
Article.mccracken.query #=> McCracken::Query: a chainable query building instance
Article.mccracken.connection #=> McCracken::Connection: Small wrapper around the Farady connection
Article.mccracken.connection.response_key_format #=> :dasherize, :camelize, nil
Article.mccracken.connection.url #=> This endpoints base URL http://api.example.com/
Article.mccracken.connection.faraday #=> The faraday object for this connection
Article.mccracken.connection = SomeNewConnectionYouPrefer
Article.mccracken.connection.configure(opts) do { |faraday_conn| } #=> Feel free to reconfigure me ;D

Persistence Resources

class Article < McCracken::Resource
  attribute :title, :string
  attribute :body, :string
  attribute :created_at, :time
end

Creating a new resource

article = Article.new
article.title = "This is a great read!"
article.save #=> Boolean: Will attempt to POST to /articles
article.errors?
article.errors #=> Array of errors

Updating a resource

article = Article.find(9)
article.title = "This is a great read!"
article.save #=> Boolean: Will attempt to PATCH to /articles
article.errors?
article.errors #=> Array of errors

Accessing Side Loaded Resources

Given the following relationship:

class Article < McCracken::Resource
  self.type = :articles
  has_one :author
  has_many :comments

  key_type :integer
  attribute :title, :string
end

class Person < McCracken::Resource
  self.type = :people
  has_many :articles

  attribute :first_name, String
  attribute :last_name, :string
  attribute :twitter, :string
  attribute :created_at, :time, default: ->{ Time.now }, serialize: ->(val){ val.to_s }
  attribute :post_count, :integer
end

class Comment < McCracken::Resource
  self.type = :comments
  has_one :author

  attribute :body, ->(val){ val.to_s }
  attribute :score, :float
  attribute :created_at, :time
  attribute :is_spam, :boolean
  attribute :mentions, :string, array: true
end

Note: When specifying relationships in McCracken, you are specifying the JSON API type name. You'll notice below that when .author is called it returns a person object. That it is because in the HTTP response, the relationship name is author but the resource type is people.

{
  "data": [{
    "type": "articles",
    "id": "1",
    "attributes": {
      "title": "JSON API paints my bikeshed!"
    },
    "relationships": {
      "author": {
        "links": {
          "self": "http://example.com/articles/1/relationships/author",
          "related": "http://example.com/articles/1/author"
        },
        "data": { "type": "people", "id": "9" }
      }
    }
  }]
}

McCracken initializes objects for side loaded resources. Only 1 HTTP call is made.

article = Article.include(:author, :comments).find(9)
article.author #=> Person object
article.comments #=> McCracken::Collection<Comment>

article.author.first_name #=> Chauncy

Configuration

McCracken is designed to support multiple connections or API endpoints. A connection is a wrapper around Faraday::Connection that includes a few pieces of middleware for parsing and encoding requests and responses to JSON API Spec.

Setting the default connection:

McCracken.configure(url: 'http://api.example.com') do |c|
  c.use MyCustomMiddleware
  c.use AllTheMiddlewares
end

Each McCracken::Resource has its own McCracken::Client. The client copies the default connection so its easy to set general configuration options, and overwrite them on a resource by resource basis.

McCracken.configure(url: 'http://api.example.com', response_key_format: :dasherize)

class Kitten < McCracken::Resource
  mccracken.url = "http://api.differentsite.com"
end

# Overwritten URL
Kitten.mccracken.connection.url #=> "http://api.differentsite.com"
# Copied key format
Kitten.mccracken.connection.response_key_format #=> :dasherize

McCracken.default_connection.url #=> "http://api.example.com"
McCracken.default_connection.response_key_format #=> :dasherize

Configuration Options

McCracken.configure(url: 'http://api.example.com', response_key_format: :dasherize) do |conn|
  conn.use SomeCoolFaradayMiddleware
end

Two special options can be passed into .configure:

• url the base url for this endpoint
• response_key_format the format of the JSONAPI response keys. Valid values are: :dasherize, :camelize, nil

Additinally any Faraday Connection options can be passed. [Faraday::Connection options](https://github.com/lostisland/faraday/blob/master/lib/faraday/connection.rb Faraday::Connection)

Advanced Usage

Custom Query Builder

Since the filter param's format isn't specified in the spec this implementation uses JSONAPI::Resource's implementation

To override, implement your own custom query builder inheriting from McCracken::Query. McCracken::Client takes a Query class to use. This method could be overwritten in your Resource:

class MyBuilder < McCracken::Query
  def filter_to_query_value
    # ... your fancier logic
  end
end

Article.mccracken.query_builder = MyBuilder
Article.mccracken.filter(:name => "Chauncy") #=> MyBuilder instance

Without inheriting from McCracken::Resource

If for some reason you cannot inherit from McCracken::Resource, you can still get a lot of JSONAPI parsing functionality

class Album
  # Just some attr accessors, NBD
  attr_accessor :id
  attr_accessor :title

  # Give Album a client to use
  def self.mccracken
    return @mccracken if @mccracken
    @mccracken = McCracken::Client.new
  end

  # Set the type, note, this is not being set on self
  mccracken.type = :albums

  # Register the type w/ mccracken
  McCracken.register_type(mccracken.type, self)

  # When you aren't inherited from McCracken::Resource, McCracken will pass a McCracken::Document to a static method called mccracken_initializer for you to initialze your record as you wish
  def self.mccracken_initializer(document)
    new(document.id, document.attributes[:title])
  end

  def initialize(id, title)
    @id    = id
    @title = title
  end
end

albums = Album.mccracken.include(:songs).fetch
albums.first.title #=> An album title!

Any ol' object (Register type, add mccracken_initializer)

As long as a class is registered with mccracken and it response to mccracken_initializer, McCracken will be able to initialize the object with or without a client

Extending the example above...

class Song
  attr_reader :name
  def self.mccracken_initializer(document)
    new(document.attributes[:name])
  end

  def initialize(name)
    @name = name
  end
end

McCracken.register_type :songs, Song

album = Album.mccracken.include(:songs).find(9)
album.songs #=> McCracken::Collection<Song>

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/jgnagy/mccracken. Base hotfixes off of the master branch and features off of the develop branch.

TODOS

• Update Yard docs :D
• Posting/Putting relationships
• A few pending tests :/
• Collection#next (queries for next page, if pagination present)
• Related Documents/Resources taking advantage of underlying resource[links]
• Error object to wrap an individual error
• consider enumerable protocol on a query
• Handle null/empty responses...
• Pluggable pagination?
• Query#find([...]) find multiple records