Use data loader

.rubocop.yml

@@ -142,4 +142,4 @@ GraphQL/ObjectDescription:
   Exclude:
     - app/graphql/application_schema.rb
     - app/graphql/types/base_**.rb
-    - app/graphql/loaders/**/*
+    - app/graphql/sources/**/*

Gemfile

@@ -14,7 +14,6 @@ gem "bootsnap", require: false
 gem "enumerize"
 gem "google-api-client"
 gem "graphql"
-gem "graphql-batch"
 gem "graphql-persisted_queries"
 gem "graphql-rails_logger"
 gem "health_check"

Gemfile.lock

@@ -167,9 +167,6 @@ GEM
       os (>= 0.9, < 2.0)
       signet (>= 0.16, < 2.a)
     graphql (2.0.22)
-    graphql-batch (0.5.3)
-      graphql (>= 1.12.18, < 3)
-      promise.rb (~> 0.7.2)
     graphql-persisted_queries (1.7.0)
       graphql (>= 1.12)
     graphql-rails_logger (1.2.4)
@@ -234,7 +231,6 @@ GEM
     parser (3.2.2.1)
       ast (~> 2.4.1)
     pg (1.5.3)
-    promise.rb (0.7.4)
     public_suffix (5.0.1)
     puma (6.2.2)
       nio4r (~> 2.0)
@@ -392,7 +388,6 @@ DEPENDENCIES
   ffaker
   google-api-client
   graphql
-  graphql-batch
   graphql-persisted_queries
   graphql-rails_logger
   health_check

app/graphql/application_schema.rb

@@ -1,10 +1,8 @@
-require "graphql/batch"
-
 class ApplicationSchema < GraphQL::Schema
   mutation(Types::MutationType)
   query(Types::QueryType)
 
-  use GraphQL::Batch
+  use GraphQL::Dataloader
   use GraphQL::PersistedQueries,
       compiled_queries: true,
       store: :redis_with_local_cache,

app/graphql/sources/active_record_object.rb

@@ -0,0 +1,13 @@
+module Sources
+  class ActiveRecordObject < GraphQL::Dataloader::Source
+    def initialize(model_class)
+      super()
+      @model_class = model_class
+    end
+
+    def fetch(ids)
+      records = @model_class.where(id: ids)
+      ids.map { |id| records.find { |r| r.id == id.to_i } }
+    end
+  end
+end

app/graphql/types/activity_type.rb

@@ -11,7 +11,7 @@ class ActivityType < Types::BaseObject
     field :user, Types::UserType, "Activity initiator", null: false
 
     def user
-      Loaders::RecordLoader.for(User).load(object.user_id)
+      dataloader.with(Sources::ActiveRecordObject, User).load(object.user_id)
     end
   end
 end

app/graphql/types/public_activity_type.rb

@@ -6,5 +6,10 @@ class PublicActivityType < Types::BaseObject
 
     field :body, String, "Body", null: false
     field :title, String, "Title", null: false
+    field :user, Types::UserType, "Activity initiator", null: false
+
+    def user
+      dataloader.with(Sources::ActiveRecordObject, User).load(object.user_id)
+    end
   end
 end

spec/graphql/types/activity_type_n_plus_one_spec.rb

@@ -1,6 +1,6 @@
 require "rails_helper"
 
-describe Types::ActivityType, :n_plus_one do
+describe Types::ActivityType do
   let!(:user) { create(:user) }
 
   let(:query) do
@@ -21,7 +21,11 @@
     GRAPHQL
   end
 
-  populate { |n| create_list(:activity, n, user: user) }
+  it_behaves_like "succeed graphql request"
 
-  include_examples "performs constant number of queries request"
+  context "when N+1", :n_plus_one do
+    populate { |n| create_list(:activity, n, user: user) }
+
+    include_examples "performs constant number of queries request"
+  end
 end

spec/support/shared_examples/succeed_graphql_request.rb

@@ -0,0 +1,7 @@
+shared_examples "succeed graphql request" do
+  let(:response) { ApplicationSchema.execute(query).as_json }
+
+  it "succeeds" do
+    expect(response["errors"]).to be_blank
+  end
+end