GraphQL Api With Rails

Graphql is an awesome new technology which is making it easier for clientside developers to iterate quickly and batch together network requests.

I really like the promise provided by GraphQl however it is not as easyas rest to get up and running on immediately. This blog post takes a lookat how to build a working GraphQL backend in just a few steps using rails.

I am using my own project graphql-api as a framework for building out the GraphQL backend.

We will look at building a basic blogging application. A blog will havean author and some tags.

First create the rails backend.

rails new blog-api --api

Add the necessary libraries to the Gemfile

gem 'graphql'gem 'graphql-api'

Create our models

rails g model Author name:stringrails g model Blog title:string content:text author:referencesrails db:migrate

Add our has many relations to author class

class Authorhas_many :blogsend

Great! Now we have a basic setup for our blogging backend. Let's add somecontrollers to serve basic Graphql queries.

Add the following file to app/controllers/graphql_controller.rb.

class GraphqlController < ApplicationControllerSCHEMA = GraphQL::Api::Schema.new.schema

def createrender json: SCHEMA.execute(params[:query],variables: params[:variables] || {},)end

end

Add the following route to config/routes.rb

resources :graphql, only: :create

Now let's test out the new api with curl. Start up the server and run thefollowing command to see if we have any blog posts

curl -XPOST -d 'query=query { blogs { id } }' \localhost:3000/graphql

{"data":{"blogs":[]}}

Let's create an author

curl -XPOST \-d 'query=mutation {createAuthor(input: {name: "foobar"}) {author { id }}}' localhost:3000/graphql

{"data":{"createAuthor":{"author":{"id":1}}}}

Now let's create a blog with that author's id

curl -XPOST \-d 'query=mutation {createBlog(input: {title: "foobar", author_id: 1}) {blog { id }}}' localhost:3000/graphql

{"data":{"createBlog":{"blog":{"id":1}}}}

Let’s try that first query again, but this time let’s try and return the blog authors as well as the blog name.

curl -XPOST -d 'query=query {blogs {idtitlecontentauthor {name}}}' localhost:3000/graphql

You can also run updateBlog mutations as well as updateAuthor mutations. Try deleting an author or blog and see what responses you get back.

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