Hackernoon logoGraphQL Api With Rails by@coldog

GraphQL Api With Rails

Colin Walker Hacker Noon profile picture

Colin Walker

Developer

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

I really like the promise provided by GraphQl however it is not as easy
as rest to get up and running on immediately. This blog post takes a look
at 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 have
an 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:string
rails g model Blog title:string content:text author:references
rails db:migrate

Add our has many relations to author class

class Author
has_many :blogs
end

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

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

class GraphqlController < ApplicationController
SCHEMA = GraphQL::Api::Schema.new.schema
  def create
render 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 the
following 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}}}}

Letโ€™s try that first query again, but this time letโ€™s try and return the blog authors as well as the blog name.

curl -XPOST -d 'query=query { 
blogs {
id
title
content
author {
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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