Getting Started: bundle graphql, graphiql

Gemfile

@@ -19,6 +19,9 @@ gem 'jbuilder', '~> 2.7'
 # Reduces boot times through caching; required in config/boot.rb
 gem 'bootsnap', '>= 1.4.2', require: false
 
+# Graphql rails
+gem 'graphql', '1.9.17'
+
 group :development, :test do
   # Call 'byebug' anywhere in the code to stop execution and get a debugger console
   gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
@@ -35,3 +38,6 @@ end
 
 # Windows does not include zoneinfo files, so bundle the tzinfo-data gem
 gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]
+
+# Graphiql GUI
+gem 'graphiql-rails', '1.7.0', group: :development

Gemfile.lock

@@ -67,6 +67,10 @@ GEM
     ffi (1.13.1)
     globalid (0.4.2)
       activesupport (>= 4.2.0)
+    graphiql-rails (1.7.0)
+      railties
+      sprockets-rails
+    graphql (1.9.17)
     i18n (1.8.5)
       concurrent-ruby (~> 1.0)
     jbuilder (2.10.1)
@@ -168,6 +172,8 @@ PLATFORMS
 DEPENDENCIES
   bootsnap (>= 1.4.2)
   byebug
+  graphiql-rails (= 1.7.0)
+  graphql (= 1.9.17)
   jbuilder (~> 2.7)
   listen (~> 3.2)
   puma (~> 4.1)

app/controllers/graphql_controller.rb

@@ -0,0 +1,48 @@
+class GraphqlController < ApplicationController
+  # If accessing from outside this domain, nullify the session
+  # This allows for outside API access while preventing CSRF attacks,
+  # but you'll have to authenticate your user separately
+  # protect_from_forgery with: :null_session
+
+  def execute
+    variables = ensure_hash(params[:variables])
+    query = params[:query]
+    operation_name = params[:operationName]
+    context = {
+      # Query context goes here, for example:
+      # current_user: current_user,
+    }
+    result = RailsHowtographqlSchema.execute(query, variables: variables, context: context, operation_name: operation_name)
+    render json: result
+  rescue => e
+    raise e unless Rails.env.development?
+    handle_error_in_development e
+  end
+
+  private
+
+  # Handle form data, JSON body, or a blank value
+  def ensure_hash(ambiguous_param)
+    case ambiguous_param
+    when String
+      if ambiguous_param.present?
+        ensure_hash(JSON.parse(ambiguous_param))
+      else
+        {}
+      end
+    when Hash, ActionController::Parameters
+      ambiguous_param
+    when nil
+      {}
+    else
+      raise ArgumentError, "Unexpected parameter: #{ambiguous_param}"
+    end
+  end
+
+  def handle_error_in_development(e)
+    logger.error e.message
+    logger.error e.backtrace.join("\n")
+
+    render json: { error: { message: e.message, backtrace: e.backtrace }, data: {} }, status: 500
+  end
+end

app/graphql/mutations/base_mutation.rb

@@ -0,0 +1,8 @@
+module Mutations
+  class BaseMutation < GraphQL::Schema::RelayClassicMutation
+    argument_class Types::BaseArgument
+    field_class Types::BaseField
+    input_object_class Types::BaseInputObject
+    object_class Types::BaseObject
+  end
+end

app/graphql/rails_howtographql_schema.rb

@@ -0,0 +1,4 @@
+class RailsHowtographqlSchema < GraphQL::Schema
+  mutation(Types::MutationType)
+  query(Types::QueryType)
+end

app/graphql/types/base_argument.rb

@@ -0,0 +1,4 @@
+module Types
+  class BaseArgument < GraphQL::Schema::Argument
+  end
+end

app/graphql/types/base_enum.rb

@@ -0,0 +1,4 @@
+module Types
+  class BaseEnum < GraphQL::Schema::Enum
+  end
+end

app/graphql/types/base_field.rb

@@ -0,0 +1,5 @@
+module Types
+  class BaseField < GraphQL::Schema::Field
+    argument_class Types::BaseArgument
+  end
+end

app/graphql/types/base_input_object.rb

@@ -0,0 +1,5 @@
+module Types
+  class BaseInputObject < GraphQL::Schema::InputObject
+    argument_class Types::BaseArgument
+  end
+end

app/graphql/types/base_interface.rb

@@ -0,0 +1,7 @@
+module Types
+  module BaseInterface
+    include GraphQL::Schema::Interface
+
+    field_class Types::BaseField
+  end
+end

app/graphql/types/base_object.rb

@@ -0,0 +1,5 @@
+module Types
+  class BaseObject < GraphQL::Schema::Object
+    field_class Types::BaseField
+  end
+end

app/graphql/types/base_scalar.rb

@@ -0,0 +1,4 @@
+module Types
+  class BaseScalar < GraphQL::Schema::Scalar
+  end
+end

app/graphql/types/base_union.rb

@@ -0,0 +1,4 @@
+module Types
+  class BaseUnion < GraphQL::Schema::Union
+  end
+end

app/graphql/types/mutation_type.rb

@@ -0,0 +1,10 @@
+module Types
+  class MutationType < Types::BaseObject
+    # TODO: remove me
+    field :test_field, String, null: false,
+      description: "An example field added by the generator"
+    def test_field
+      "Hello World"
+    end
+  end
+end

app/graphql/types/query_type.rb

@@ -0,0 +1,13 @@
+module Types
+  class QueryType < Types::BaseObject
+    # Add root-level fields here.
+    # They will be entry points for queries on your schema.
+
+    # TODO: remove me
+    field :test_field, String, null: false,
+      description: "An example field added by the generator"
+    def test_field
+      "Hello World!"
+    end
+  end
+end

config/routes.rb

@@ -1,3 +1,7 @@
 Rails.application.routes.draw do
+  if Rails.env.development?
+    mount GraphiQL::Rails::Engine, at: "/graphiql", graphql_path: "/graphql"
+  end
+  post "/graphql", to: "graphql#execute"
   # For details on the DSL available within this file, see https://guides.rubyonrails.org/routing.html
 end