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https://github.com/Netflix/fast_jsonapi

No Longer Maintained - A lightning fast JSON:API serializer for Ruby Objects.
https://github.com/Netflix/fast_jsonapi

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No Longer Maintained - A lightning fast JSON:API serializer for Ruby Objects.

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# Fast JSON API — :warning: This project is no longer maintained!!!! :warning:



[![Build Status](https://travis-ci.org/Netflix/fast_jsonapi.svg?branch=master)](https://travis-ci.org/Netflix/fast_jsonapi)



A lightning fast [JSON:API](http://jsonapi.org/) serializer for Ruby Objects.



### Since this project is no longer maintained, please consider using alternatives or the forked project [jsonapi-serializer/jsonapi-serializer](https://github.com/jsonapi-serializer/jsonapi-serializer)!



# Performance Comparison



We compare serialization times with Active Model Serializer as part of RSpec performance tests included on this library. We want to ensure that with every change on this library, serialization time is at least `25 times` faster than Active Model Serializers on up to current benchmark of 1000 records. Please read the [performance document](https://github.com/Netflix/fast_jsonapi/blob/master/performance_methodology.md) for any questions related to methodology.



## Benchmark times for 250 records



```bash

$ rspec

Active Model Serializer serialized 250 records in 138.71 ms

Fast JSON API serialized 250 records in 3.01 ms

```



# Table of Contents



* [Features](#features)

* [Installation](#installation)

* [Usage](#usage)

  * [Rails Generator](#rails-generator)

  * [Model Definition](#model-definition)

  * [Serializer Definition](#serializer-definition)

  * [Object Serialization](#object-serialization)

  * [Compound Document](#compound-document)

  * [Key Transforms](#key-transforms)

  * [Collection Serialization](#collection-serialization)

  * [Caching](#caching)

  * [Params](#params)

  * [Conditional Attributes](#conditional-attributes)

  * [Conditional Relationships](#conditional-relationships)

  * [Sparse Fieldsets](#sparse-fieldsets)

  * [Using helper methods](#using-helper-methods)

* [Contributing](#contributing)



## Features



* Declaration syntax similar to Active Model Serializer

* Support for `belongs_to`, `has_many` and `has_one`

* Support for compound documents (included)

* Optimized serialization of compound documents

* Caching



## Installation



Add this line to your application's Gemfile:



```ruby

gem 'fast_jsonapi'

```



Execute:



```bash

$ bundle install

```



## Usage



### Rails Generator

You can use the bundled generator if you are using the library inside of

a Rails project:



    rails g serializer Movie name year



This will create a new serializer in `app/serializers/movie_serializer.rb`



### Model Definition



```ruby

class Movie

  attr_accessor :id, :name, :year, :actor_ids, :owner_id, :movie_type_id

end

```



### Serializer Definition



```ruby

class MovieSerializer

  include FastJsonapi::ObjectSerializer

  set_type :movie  # optional

  set_id :owner_id # optional

  attributes :name, :year

  has_many :actors

  belongs_to :owner, record_type: :user

  belongs_to :movie_type

end

```



### Sample Object



```ruby

movie = Movie.new

movie.id = 232

movie.name = 'test movie'

movie.actor_ids = [1, 2, 3]

movie.owner_id = 3

movie.movie_type_id = 1

movie

```



### Object Serialization



#### Return a hash

```ruby

hash = MovieSerializer.new(movie).serializable_hash

```



#### Return Serialized JSON

```ruby

json_string = MovieSerializer.new(movie).serialized_json

```



#### Serialized Output



```json

{

  "data": {

    "id": "3",

    "type": "movie",

    "attributes": {

      "name": "test movie",

      "year": null

    },

    "relationships": {

      "actors": {

        "data": [

          {

            "id": "1",

            "type": "actor"

          },

          {

            "id": "2",

            "type": "actor"

          }

        ]

      },

      "owner": {

        "data": {

          "id": "3",

          "type": "user"

        }

      }

    }

  }

}



```



### Key Transforms

By default fast_jsonapi underscores the key names. It supports the same key transforms that are supported by AMS. Here is the syntax of specifying a key transform



```ruby

class MovieSerializer

  include FastJsonapi::ObjectSerializer

  # Available options :camel, :camel_lower, :dash, :underscore(default)

  set_key_transform :camel

end

```

Here are examples of how these options transform the keys



```ruby

set_key_transform :camel # "some_key" => "SomeKey"

set_key_transform :camel_lower # "some_key" => "someKey"

set_key_transform :dash # "some_key" => "some-key"

set_key_transform :underscore # "some_key" => "some_key"

```



### Attributes

Attributes are defined in FastJsonapi using the `attributes` method.  This method is also aliased as `attribute`, which is useful when defining a single attribute.



By default, attributes are read directly from the model property of the same name.  In this example, `name` is expected to be a property of the object being serialized:



```ruby

class MovieSerializer

  include FastJsonapi::ObjectSerializer



  attribute :name

end

```



Custom attributes that must be serialized but do not exist on the model can be declared using Ruby block syntax:



```ruby

class MovieSerializer

  include FastJsonapi::ObjectSerializer



  attributes :name, :year



  attribute :name_with_year do |object|

    "#{object.name} (#{object.year})"

  end

end

```



The block syntax can also be used to override the property on the object:



```ruby

class MovieSerializer

  include FastJsonapi::ObjectSerializer



  attribute :name do |object|

    "#{object.name} Part 2"

  end

end

```



Attributes can also use a different name by passing the original method or accessor with a proc shortcut:



```ruby

class MovieSerializer

  include FastJsonapi::ObjectSerializer



  attributes :name



  attribute :released_in_year, &:year

end

```



### Links Per Object

Links are defined in FastJsonapi using the `link` method. By default, links are read directly from the model property of the same name. In this example, `public_url` is expected to be a property of the object being serialized.



You can configure the method to use on the object for example a link with key `self` will get set to the value returned by a method called `url` on the movie object.



You can also use a block to define a url as shown in `custom_url`. You can access params in these blocks as well as shown in `personalized_url`



```ruby

class MovieSerializer

  include FastJsonapi::ObjectSerializer



  link :public_url



  link :self, :url



  link :custom_url do |object|

    "http://movies.com/#{object.name}-(#{object.year})"

  end



  link :personalized_url do |object, params|

    "http://movies.com/#{object.name}-#{params[:user].reference_code}"

  end

end

```



#### Links on a Relationship



You can specify [relationship links](http://jsonapi.org/format/#document-resource-object-relationships) by using the `links:` option on the serializer. Relationship links in JSON API are useful if you want to load a parent document and then load associated documents later due to size constraints (see [related resource links](http://jsonapi.org/format/#document-resource-object-related-resource-links))



```ruby

class MovieSerializer

  include FastJsonapi::ObjectSerializer



  has_many :actors, links: {

    self: :url,

    related: -> (object) {

      "https://movies.com/#{object.id}/actors"

    }

  }

end

```



This will create a `self` reference for the relationship, and a `related` link for loading the actors relationship later. NB: This will not automatically disable loading the data in the relationship, you'll need to do that using the `lazy_load_data` option:



```ruby

  has_many :actors, lazy_load_data: true, links: {

    self: :url,

    related: -> (object) {

      "https://movies.com/#{object.id}/actors"

    }

  }

```



### Meta Per Resource



For every resource in the collection, you can include a meta object containing non-standard meta-information about a resource that can not be represented as an attribute or relationship.



```ruby

class MovieSerializer

  include FastJsonapi::ObjectSerializer



  meta do |movie|

    {

      years_since_release: Date.current.year - movie.year

    }

  end

end

```



### Compound Document



Support for top-level and nested included associations through ` options[:include] `.



```ruby

options = {}

options[:meta] = { total: 2 }

options[:links] = {

  self: '...',

  next: '...',

  prev: '...'

}

options[:include] = [:actors, :'actors.agency', :'actors.agency.state']

MovieSerializer.new([movie, movie], options).serialized_json

```



### Collection Serialization



```ruby

options[:meta] = { total: 2 }

options[:links] = {

  self: '...',

  next: '...',

  prev: '...'

}

hash = MovieSerializer.new([movie, movie], options).serializable_hash

json_string = MovieSerializer.new([movie, movie], options).serialized_json

```



#### Control Over Collection Serialization



You can use `is_collection` option to have better control over collection serialization.



If this option is not provided or `nil` autedetect logic is used to try understand

if provided resource is a single object or collection.



Autodetect logic is compatible with most DB toolkits (ActiveRecord, Sequel, etc.) but

**cannot** guarantee that single vs collection will be always detected properly.



```ruby

options[:is_collection]

```



was introduced to be able to have precise control this behavior



- `nil` or not provided: will try to autodetect single vs collection (please, see notes above)

- `true` will always treat input resource as *collection*

- `false` will always treat input resource as *single object*



### Caching

Requires a `cache_key` method be defined on model:



```ruby

class MovieSerializer

  include FastJsonapi::ObjectSerializer

  set_type :movie  # optional

  cache_options enabled: true, cache_length: 12.hours

  attributes :name, :year

end

```



### Params



In some cases, attribute values might require more information than what is

available on the record, for example, access privileges or other information

related to a current authenticated user. The `options[:params]` value covers these

cases by allowing you to pass in a hash of additional parameters necessary for

your use case.



Leveraging the new params is easy, when you define a custom attribute or relationship with a

block you opt-in to using params by adding it as a block parameter.



```ruby

class MovieSerializer

  include FastJsonapi::ObjectSerializer



  attributes :name, :year

  attribute :can_view_early do |movie, params|

    # in here, params is a hash containing the `:current_user` key

    params[:current_user].is_employee? ? true : false

  end



  belongs_to :primary_agent do |movie, params|

    # in here, params is a hash containing the `:current_user` key

    params[:current_user].is_employee? ? true : false

  end

end



# ...

current_user = User.find(cookies[:current_user_id])

serializer = MovieSerializer.new(movie, {params: {current_user: current_user}})

serializer.serializable_hash

```



Custom attributes and relationships that only receive the resource are still possible by defining

the block to only receive one argument.



### Conditional Attributes



Conditional attributes can be defined by passing a Proc to the `if` key on the `attribute` method. Return `true` if the attribute should be serialized, and `false` if not. The record and any params passed to the serializer are available inside the Proc as the first and second parameters, respectively.



```ruby

class MovieSerializer

  include FastJsonapi::ObjectSerializer



  attributes :name, :year

  attribute :release_year, if: Proc.new { |record|

    # Release year will only be serialized if it's greater than 1990

    record.release_year > 1990

  }



  attribute :director, if: Proc.new { |record, params|

    # The director will be serialized only if the :admin key of params is true

    params && params[:admin] == true

  }

end



# ...

current_user = User.find(cookies[:current_user_id])

serializer = MovieSerializer.new(movie, { params: { admin: current_user.admin? }})

serializer.serializable_hash

```



### Conditional Relationships



Conditional relationships can be defined by passing a Proc to the `if` key. Return `true` if the relationship should be serialized, and `false` if not. The record and any params passed to the serializer are available inside the Proc as the first and second parameters, respectively.



```ruby

class MovieSerializer

  include FastJsonapi::ObjectSerializer



  # Actors will only be serialized if the record has any associated actors

  has_many :actors, if: Proc.new { |record| record.actors.any? }



  # Owner will only be serialized if the :admin key of params is true

  belongs_to :owner, if: Proc.new { |record, params| params && params[:admin] == true }

end



# ...

current_user = User.find(cookies[:current_user_id])

serializer = MovieSerializer.new(movie, { params: { admin: current_user.admin? }})

serializer.serializable_hash

```



### Sparse Fieldsets



Attributes and relationships can be selectively returned per record type by using the `fields` option.



```ruby

class MovieSerializer

  include FastJsonapi::ObjectSerializer



  attributes :name, :year

end



serializer = MovieSerializer.new(movie, { fields: { movie: [:name] } })

serializer.serializable_hash

```



### Using helper methods



You can mix-in code from another ruby module into your serializer class to reuse functions across your app.



Since a serializer is evaluated in a the context of a `class` rather than an `instance` of a class, you need to make sure that your methods act as `class` methods when mixed in.



##### Using ActiveSupport::Concern



``` ruby



module AvatarHelper

  extend ActiveSupport::Concern



  class_methods do

    def avatar_url(user)

      user.image.url

    end

  end

end



class UserSerializer

  include FastJsonapi::ObjectSerializer



  include AvatarHelper # mixes in your helper method as class method



  set_type :user



  attributes :name, :email



  attribute :avatar do |user|

    avatar_url(user)

  end

end



```



##### Using Plain Old Ruby



``` ruby

module AvatarHelper

  def avatar_url(user)

    user.image.url

  end

end



class UserSerializer

  include FastJsonapi::ObjectSerializer



  extend AvatarHelper # mixes in your helper method as class method



  set_type :user



  attributes :name, :email



  attribute :avatar do |user|

    avatar_url(user)

  end

end



```



### Customizable Options



Option | Purpose | Example

------------ | ------------- | -------------

set_type | Type name of Object | ```set_type :movie ```

key | Key of Object | ```belongs_to :owner, key: :user ```

set_id | ID of Object | ```set_id :owner_id ``` or ```set_id { |record| "#{record.name.downcase}-#{record.id}" }```

cache_options | Hash to enable caching and set cache length | ```cache_options enabled: true, cache_length: 12.hours, race_condition_ttl: 10.seconds```

id_method_name | Set custom method name to get ID of an object (If block is provided for the relationship, `id_method_name` is invoked on the return value of the block instead of the resource object) | ```has_many :locations, id_method_name: :place_ids ```

object_method_name | Set custom method name to get related objects | ```has_many :locations, object_method_name: :places ```

record_type | Set custom Object Type for a relationship | ```belongs_to :owner, record_type: :user```

serializer | Set custom Serializer for a relationship | ```has_many :actors, serializer: :custom_actor``` or ```has_many :actors, serializer: MyApp::Api::V1::ActorSerializer```

polymorphic | Allows different record types for a polymorphic association | ```has_many :targets, polymorphic: true```

polymorphic | Sets custom record types for each object class in a polymorphic association | ```has_many :targets, polymorphic: { Person => :person, Group => :group }```



### Instrumentation



`fast_jsonapi` also has builtin [Skylight](https://www.skylight.io/) integration. To enable, add the following to an initializer:



```ruby

require 'fast_jsonapi/instrumentation/skylight'

```



Skylight relies on `ActiveSupport::Notifications` to track these two core methods. If you would like to use these notifications without using Skylight, simply require the instrumentation integration:



```ruby

require 'fast_jsonapi/instrumentation'

```



The two instrumented notifcations are supplied by these two constants:

* `FastJsonapi::ObjectSerializer::SERIALIZABLE_HASH_NOTIFICATION`

* `FastJsonapi::ObjectSerializer::SERIALIZED_JSON_NOTIFICATION`



It is also possible to instrument one method without the other by using one of the following require statements:



```ruby

require 'fast_jsonapi/instrumentation/serializable_hash'

require 'fast_jsonapi/instrumentation/serialized_json'

```



Same goes for the Skylight integration:

```ruby

require 'fast_jsonapi/instrumentation/skylight/normalizers/serializable_hash'

require 'fast_jsonapi/instrumentation/skylight/normalizers/serialized_json'

```



## Contributing

Please see [contribution check](https://github.com/Netflix/fast_jsonapi/blob/master/CONTRIBUTING.md) for more details on contributing



### Running Tests

We use [RSpec](http://rspec.info/) for testing. We have unit tests, functional tests and performance tests. To run tests use the following command:



```bash

rspec

```



To run tests without the performance tests (for quicker test runs):



```bash

rspec spec --tag ~performance:true

```



To run tests only performance tests:



```bash

rspec spec --tag performance:true

```