Fast JSON API

The Fast JSON API is a JSON serializer for Rails APIs. … The result is that in our controller actions, rather than writing a custom render each time, we write out a serializer for each object once and use Fast JSON API to control the way our data is structured.

To install JSON API add the gem to your gemfile

gem 'fast_jsonapi'

and run bundle in your terminal

$ bundle install

Now in your Rail application generalize new serializer that has same name as your controller. let say I have controller named Movie has name and year attributes.

rails g serializer Movie name year

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

let say your movie model look like this:

class Movie
  attr_accessor :id, :name, :year, :actor_ids, :owner_id,   :movie_type_id
end

your serializer in app/serializers/movie_serializer.rb

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

create new movie 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

this will return Serialized JSON that is nested hash:

json_string = MovieSerializer.new(movie).serialized_json

that look like this

{
  "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"
        }
      }
    }
  }
}

Resources

https://www.rubydoc.info/gems/fast_jsonapi/1.5