Joyful JSON API¶ ↑
This project is forked from fast_jsonapi
A lightning fast JSON:API serializer for Ruby Objects.
With this fork, we're expanding the scope of the original gem a bit. Instead of just fast jsonapi compliant responses, we want to end up with a simple toolkit to enable a rails server to quack like JSON:API with a minimum amount of developer effort.
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 for any questions related to methodology.
Benchmark times for 250 records¶ ↑
$ 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¶ ↑
-
Declaration syntax similar to Active Model Serializer
-
Support for
belongs_to
,has_many
andhas_one
-
Support for compound documents (included)
-
Optimized serialization of compound documents
-
Caching
Installation¶ ↑
Add this line to your application's Gemfile:
gem 'joyful_jsonapi'
Execute:
$ 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¶ ↑
class Movie attr_accessor :id, :name, :year, :actor_ids, :owner_id, :movie_type_id end
Serializer Definition¶ ↑
class MovieSerializer include JoyfulJsonapi::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
¶ ↑
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¶ ↑
hash = MovieSerializer.new(movie).serializable_hash
Return Serialized JSON¶ ↑
json_string = MovieSerializer.new(movie).serialized_json
Serialized Output¶ ↑
{ "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
class MovieSerializer include JoyfulJsonapi::ObjectSerializer # Available options :camel, :camel_lower, :dash, :underscore(default) set_key_transform :camel end
Here are examples of how these options transform the keys
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 JoyfulJsonapi
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:
class MovieSerializer include JoyfulJsonapi::ObjectSerializer attribute :name end
Custom attributes that must be serialized but do not exist on the model can be declared using Ruby block syntax:
class MovieSerializer include JoyfulJsonapi::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:
class MovieSerializer include JoyfulJsonapi::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:
class MovieSerializer include JoyfulJsonapi::ObjectSerializer attributes :name attribute :released_in_year, &:year end
Links Per Object
¶ ↑
Links are defined in JoyfulJsonapi
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
class MovieSerializer include JoyfulJsonapi::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 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)
class MovieSerializer include JoyfulJsonapi::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:
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.
class MovieSerializer include JoyfulJsonapi::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]
.
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¶ ↑
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.
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:
class MovieSerializer include JoyfulJsonapi::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.
class MovieSerializer include JoyfulJsonapi::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.
class MovieSerializer include JoyfulJsonapi::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.
class MovieSerializer include JoyfulJsonapi::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.
class MovieSerializer include JoyfulJsonapi::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¶ ↑
module AvatarHelper extend ActiveSupport::Concern class_methods do def avatar_url(user) user.image.url end end end class UserSerializer include JoyfulJsonapi::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¶ ↑
module AvatarHelper def avatar_url(user) user.image.url end end class UserSerializer include JoyfulJsonapi::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 }
Parsing Incoming Params¶ ↑
It's easy enough to parse incoming JSON:API parameters with regular strong params:
params.require(:data).require(:attributes).permit(:foo, :bar, :baz)
However when you introduce relationships it gets complicated. Joyful JSON:API ships a simple controller macro for turning a jsonapi incoming payload into a rails-friendly one.
class ApplicationController < ActionController::Base include JoyfulJsonapi::ParameterParser end
Then in your resource specific controller you can do this:
class FoosController < ApplicationController translate_jsonapi_params only: %w(create update) def foo_params params.require(:foo).permit(:bar, :baz) end end
Instrumentation¶ ↑
fast_jsonapi
also has builtin Skylight integration. To enable, add the following to an initializer:
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:
require 'fast_jsonapi/instrumentation'
The two instrumented notifcations are supplied by these two constants: * JoyfulJsonapi::ObjectSerializer::SERIALIZABLE_HASH_NOTIFICATION
* JoyfulJsonapi::ObjectSerializer::SERIALIZED_JSON_NOTIFICATION
It is also possible to instrument one method without the other by using one of the following require statements:
require 'fast_jsonapi/instrumentation/serializable_hash' require 'fast_jsonapi/instrumentation/serialized_json'
Same goes for the Skylight integration:
require 'fast_jsonapi/instrumentation/skylight/normalizers/serializable_hash' require 'fast_jsonapi/instrumentation/skylight/normalizers/serialized_json'
Contributing¶ ↑
Please see contribution check for more details on contributing
Running Tests¶ ↑
We use RSpec for testing. We have unit tests, functional tests and performance tests. To run tests use the following command:
rspec
To run tests without the performance tests (for quicker test runs):
rspec spec --tag ~performance:true
To run tests only performance tests:
rspec spec --tag performance:true