Added GraphQL endpoint, invoice query and mutation.

.rubocop_todo.yml

@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2017-10-24 11:24:19 -0400 using RuboCop version 0.51.0.
+# on 2017-10-24 11:26:00 -0400 using RuboCop version 0.51.0.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -12,9 +12,19 @@
 Metrics/LineLength:
   Max: 112
 
-# Offense count: 1
+# Offense count: 2
 Style/Documentation:
   Exclude:
     - 'spec/**/*'
     - 'test/**/*'
+    - 'app/controllers/graphql_controller.rb'
     - 'config/application.rb'
+
+# Offense count: 2
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle, SupportedStyles.
+# SupportedStyles: line_count_dependent, lambda, literal
+Style/Lambda:
+  Exclude:
+    - 'app/graphql/mutations/create_invoice_mutation.rb'
+    - 'app/graphql/queries.rb'

Gemfile

@@ -1,9 +1,11 @@
 source 'https://rubygems.org'
 
+gem 'graphql'
 gem 'rails', '~> 5.1.4'
 gem 'sqlite3'
 
 group :development, :test do
+  gem 'graphlient'
   gem 'listen'
   gem 'rspec-rails'
   gem 'rubocop'

Gemfile.lock

@@ -45,9 +45,21 @@ GEM
     crass (1.0.2)
     diff-lcs (1.3)
     erubi (1.7.0)
+    faraday (0.13.1)
+      multipart-post (>= 1.2, < 3)
+    faraday_middleware (0.12.2)
+      faraday (>= 0.7.4, < 1.0)
     ffi (1.9.18)
     globalid (0.4.0)
       activesupport (>= 4.2.0)
+    graphlient (0.0.7)
+      faraday
+      faraday_middleware
+      graphql-client
+    graphql (1.7.4)
+    graphql-client (0.12.1)
+      activesupport (>= 3.0, < 6.0)
+      graphql (~> 1.6)
     i18n (0.9.0)
       concurrent-ruby (~> 1.0)
     listen (3.1.5)
@@ -65,6 +77,7 @@ GEM
     mime-types-data (3.2016.0521)
     mini_portile2 (2.3.0)
     minitest (5.10.3)
+    multipart-post (2.0.0)
     nio4r (2.1.0)
     nokogiri (1.8.1)
       mini_portile2 (~> 2.3.0)
@@ -151,6 +164,8 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
+  graphlient
+  graphql
   listen
   rails (~> 5.1.4)
   rspec-rails

app/controllers/graphql_controller.rb

@@ -0,0 +1,31 @@
+class GraphqlController < ApplicationController
+  def execute
+    result = Schema.execute(
+      query,
+      variables: variables,
+      context: context,
+      operation_name: operation_name
+    )
+    render json: result
+  end
+
+  private
+
+  def query
+    params[:query]
+  end
+
+  def operation_name
+    params[:operationName]
+  end
+
+  def context
+    {}
+  end
+
+  def variables
+    variables = params[:variables]
+    variables = JSON.parse(variables) if variables && variables.is_a?(String)
+    variables || {}
+  end
+end

app/graphql/mutations.rb

@@ -0,0 +1,7 @@
+require_relative 'mutations/create_invoice_mutation'
+
+Mutation = GraphQL::ObjectType.define do
+  name 'Mutation'
+
+  field :createInvoice, field: CreateInvoiceMutation.field
+end

app/graphql/mutations/create_invoice_mutation.rb

@@ -0,0 +1,13 @@
+CreateInvoiceMutation = GraphQL::Relay::Mutation.define do
+  name 'createInvoice'
+
+  input_field :fee_in_cents, !types.Int
+  return_type InvoiceType
+
+  resolve ->(_object, inputs, _ctx) {
+    OpenStruct.new(
+      id: 1231,
+      fee_in_cents: inputs[:fee_in_cents]
+    )
+  }
+end

app/graphql/queries.rb

@@ -0,0 +1,14 @@
+Query = GraphQL::ObjectType.define do
+  name 'Query'
+
+  field :invoice, InvoiceType do
+    argument :id, !types.Int
+    description 'Get an invoice by ID.'
+    resolve ->(_obj, args, _ctx) {
+      OpenStruct.new(
+        id: args[:id],
+        fee_in_cents: 20_000
+      )
+    }
+  end
+end

app/graphql/schema.rb

@@ -0,0 +1,8 @@
+require_relative 'types'
+require_relative 'queries'
+require_relative 'mutations'
+
+Schema = GraphQL::Schema.define do
+  query Query
+  mutation Mutation
+end

app/graphql/types.rb

@@ -0,0 +1 @@
+require_relative 'types/invoice_type'

app/graphql/types/invoice_type.rb

@@ -0,0 +1,6 @@
+InvoiceType = GraphQL::ObjectType.define do
+  name 'Invoice'
+  description 'An Invoice'
+  field :id, !types.Int
+  field :fee_in_cents, types.Int
+end

config/routes.rb

@@ -1,2 +1,3 @@
 Rails.application.routes.draw do
+  post '/graphql', to: 'graphql#execute'
 end

spec/graphql/mutations/create_invoice_mutation_spec.rb

@@ -0,0 +1,23 @@
+require 'rails_helper'
+
+describe 'Create Invoice Mutation', type: :request do
+  include_context 'GraphQL Client'
+
+  let(:query) do
+    <<-GRAPHQL
+      mutation($input: createInvoiceInput!) {
+        createInvoice(input: $input) {
+          id
+          fee_in_cents
+        }
+      }
+    GRAPHQL
+  end
+
+  it 'returns an invoice' do
+    response = client.execute(query, input: { fee_in_cents: 42_000 })
+    invoice = response.data.create_invoice
+    expect(invoice.id).to eq 1231
+    expect(invoice.fee_in_cents).to eq 42_000
+  end
+end

spec/graphql/queries/invoice_query_spec.rb

@@ -0,0 +1,23 @@
+require 'rails_helper'
+
+describe 'Invoice Query', type: :request do
+  include_context 'GraphQL Client'
+
+  let(:query) do
+    <<-GRAPHQL
+      query($id: Int!) {
+        invoice(id: $id) {
+          id
+          fee_in_cents
+        }
+      }
+    GRAPHQL
+  end
+
+  it 'returns an invoice' do
+    response = client.execute(query, id: 42)
+    invoice = response.data.invoice
+    expect(invoice.id).to eq 42
+    expect(invoice.fee_in_cents).to eq 20_000
+  end
+end

spec/graphql/schema_spec.rb

@@ -0,0 +1,9 @@
+require 'rails_helper'
+
+describe 'GraphQL Schema', type: 'request' do
+  include_context 'GraphQL Client'
+
+  it 'retrieves schema' do
+    expect(client.schema).to be_a GraphQL::Schema
+  end
+end

spec/support/graphql/client.rb

@@ -0,0 +1,11 @@
+RSpec.shared_context 'GraphQL Client', shared_context: :metadata do
+  let(:client) do
+    Graphlient::Client.new('https://api.example.org/graphql') do |client|
+      client.http do |h|
+        h.connection do |c|
+          c.use Faraday::Adapter::Rack, app
+        end
+      end
+    end
+  end
+end