Rest API vs Graphql-ruby

This is the base example of using REST and GraphQL API for your rails application.

This application is using the graphql-ruby gem

• Models
• Getting all data
• Finding a record
• Creating a record
• Record deleting

Models

This app has two models: author and book:

app/models/author.rb:

class Author < ApplicationRecord

  validates :name, presence: true

  has_many :authorships, dependent: :destroy
  has_many :books, through: :authorships, dependent: :destroy

end

app/models/book.rb:

class Book < ApplicationRecord

  validates :title, presence: true

  has_many :authorships, dependent: :nullify
  has_many :authors, through: :authorships

end

Getting all data

Rest API

config/routes.rb:

namespace :api do
  namespace :v1 do
    resources :authors
  end
end

app/controllers/api/v1/authors_controller.rb:

module Api

  module V1

    class AuthorsController < ApplicationController

      def index
        authors = Author.all
        render json: authors
      end
      
    end
    
  end
  
end

app/serializers/author_serializer.rb:

class AuthorSerializer < ActiveModel::Serializer

  attributes :id, :name
  has_many :books, through: :authorships

end

Rest API request:

GET: localhost:3000/api/v1/authors:

[
  {
    "id": 16,
    "name": "Lazaro McKenzie",
    "books": [
        {
            "id": 28,
            "title": "A Catskill Eagle",
            "description": "This sounds like something The One True Morty might say."
        },
        {
            "id": 32,
            "title": "Moab Is My Washpot",
            "description": "I don't get it and I don't need to."
        }
    ]
  },
  {
      "id": 17,
      "name": "Tyrone Heller",
      "books": [
          {
              "id": 21,
              "title": "I Sing the Body Electric",
              "description": "Pluto's a planet."
          },
          {
              "id": 32,
              "title": "Moab Is My Washpot",
              "description": "I don't get it and I don't need to."
          }
      ]
  },
    {
        "id": 18,
        "name": "Shiela Williamson",
        "books": [
            {
                "id": 25,
                "title": "No Highway",
                "description": "I want that Mulan McNugget sauce, Morty!"
            }
        ]
    }
]

Graphql

Unlike the REST API GraphQL has only one endpoint:

config/routes.rb:

post "/graphql", to: "graphql#execute"

app/graphql/types/query_type.rb:

module Types

  class QueryType < Types::BaseObject

    field :authors, [Types::AuthorType], null: false

    def authors
      Author.all
    end

  end

end

GraphQL request:

This is how you can execute the query in Ruby:

query_string = "
  {
    authors {
      id
      name
      books {
        id
        title
        description
      }
    }
  }
"

RestGraphqlSchema.execute(query_string)

Finding a record

Rest API

app/controllers/api/v1/authors_controller.rb:

def show
  render json: Author.find(params[:id])
end

Rest API request:

GET: localhost:3000/api/v1/authors/16:

{
    "id": 16,
    "name": "Lazaro McKenzie",
    "books": [
        {
            "id": 28,
            "title": "A Catskill Eagle",
            "description": "This sounds like something The One True Morty might say."
        },
        {
            "id": 32,
            "title": "Moab Is My Washpot",
            "description": "I don't get it and I don't need to."
        }
    ]
}

GraphQL

app/graphql/types/query_type.rb

field :author, Types::AuthorType, null: true do
  argument :id, ID, required: true
end

def author(id:)
  Author.find_by(id: id)
end

Request:

Creating a record

Rest API

app/controllers/api/v1/authors_controller.rb:

def create
  author = Author.new(author_params)
  if author.save
    render json: author, status: :created
  else
    render json: author.errors, status: :unprocessable_entity
  end
end

private

def author_params
  params.require(:author).permit(:name)
end

Rest API request:

POST: localhost:3000/api/v1/authors:

Params: author[name]: "Robert B. Parker"

{
    "id": 58,
    "name": "Robert B. Parker",
    "books": []
}

GraphQL

app/graphql/types/mutation_type.rb:

module Types

  class MutationType < Types::BaseObject

    field :create_author,  mutation: Mutations::AuthorMutations::CreateAuthor

  end

end

app/graphql/mutations/author_mutations/create_author.rb:

module Mutations

  module AuthorMutations

    class CreateAuthor < Mutations::BaseMutation

      null true

      argument :name, String, required: true

      field :author, Types::AuthorType, null: true
      field :errors, [String], null: false

      def resolve(name:)
        author = Author.create(name: name)
        if author.present?
          # Successful creation, return the created object with no errors
          {
            author: author,
            errors: []
          }
        else
          # Failed save, return the errors to the client
          {
            author: nil,
            errors: author.errors.full_messages
          }
        end
      end

    end

  end

end

Request:

Record deleting

Rest API

app/controllers/api/v1/authors_controller.rb:

def destroy
  @author.destroy
end

private

def set_author
  @author = Author.find(params[:id])
end

DELETE: localhost:3000/api/v1/authors/58:

Status: 204 No Content

GraphQL

app/graphql/mutations/author_mutations/destroy_author.rb:

field :destroy_author, mutation: Mutations::AuthorMutations::DestroyAuthor

app/graphql/mutations/author_mutations/destroy_author.rb:

module Mutations

  module AuthorMutations

    class DestroyAuthor < Mutations::BaseMutation

      null false

      argument :id, ID, 'the ID of the author to delete', required: true

      field :author, Types::AuthorType, null: true
      field :errors, [String], null: false

      def resolve(id:)
        author = Author.find_by(id: id)
        author&.destroy
        {
          author: author,
          errors: []
        }
      end

    end

  end

end

Request:

If you try delete the same record again server will response with empty object:

Useful links

• GraphQL or REST? What should I use?
• GraphQL guide
• How to graphql tutorial

License

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