Initial setup GraphQL using graphql-ruby 1.8

- All definitions have been replaced by classes:
  http://graphql-ruby.org/schema/class_based_api.html
- Authorization & Presentation have been refactored to work in the
  class based system
- Loaders have been replaced by resolvers
- Times are now coersed as ISO 8601

21 files changed, 218 insertions, 182 deletions

diff --git a/app/graphql/functions/base_function.rb b/app/graphql/functions/base_function.rb
new file mode 100644
index 00000000000..42fb8f99acc
--- /dev/null
+++ b/app/graphql/functions/base_function.rb
@@ -0,0 +1,4 @@
+module Functions
+  class BaseFunction < GraphQL::Function
+  end
+end
diff --git a/app/graphql/functions/echo.rb b/app/graphql/functions/echo.rb
new file mode 100644
index 00000000000..e5bf109b8d7
--- /dev/null
+++ b/app/graphql/functions/echo.rb
@@ -0,0 +1,13 @@
+module Functions
+  class Echo < BaseFunction
+    argument :text, GraphQL::STRING_TYPE
+
+    description "Testing endpoint to validate the API with"
+
+    def call(obj, args, ctx)
+      username = ctx[:current_user]&.username
+
+      "#{username.inspect} says: #{args[:text]}"
+    end
+  end
+end
diff --git a/app/graphql/gitlab_schema.rb b/app/graphql/gitlab_schema.rb
index ac75c4bf2e3..de4fc1d8e32 100644
--- a/app/graphql/gitlab_schema.rb
+++ b/app/graphql/gitlab_schema.rb
@@ -1,12 +1,8 @@
-Gitlab::Graphql::Authorize.register!
-Gitlab::Graphql::Present.register!
-
-GitlabSchema = GraphQL::Schema.define do
+class GitlabSchema < GraphQL::Schema
   use BatchLoader::GraphQL
-
-  enable_preloading
-  enable_authorization
-  enable_presenting
+  use Gitlab::Graphql::Authorize
+  use Gitlab::Graphql::Present
 
   query(Types::QueryType)
+  # mutation(Types::MutationType)
 end
diff --git a/app/graphql/loaders/base_loader.rb b/app/graphql/loaders/base_loader.rb
deleted file mode 100644
index aad435ea09b..00000000000
--- a/app/graphql/loaders/base_loader.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-# Helper methods for all loaders
-module Loaders::BaseLoader
-  extend ActiveSupport::Concern
-
-  class_methods do
-    # Convert a class method into a resolver proc. The method should follow the
-    # (obj, args, ctx) calling convention
-    def [](sym)
-      resolver = method(sym)
-      raise ArgumentError.new("#{self}.#{sym} is not a resolver") unless resolver.arity == 3
-
-      resolver
-    end
-  end
-end
diff --git a/app/graphql/loaders/iid_loader.rb b/app/graphql/loaders/iid_loader.rb
deleted file mode 100644
index f9827765a92..00000000000
--- a/app/graphql/loaders/iid_loader.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-class Loaders::IidLoader
-  include Loaders::BaseLoader
-
-  class << self
-    def merge_request(obj, args, ctx)
-      iid = args[:iid]
-      project = Loaders::FullPathLoader.project_by_full_path(args[:project])
-      merge_request_by_project_and_iid(project, iid)
-    end
-
-    def merge_request_by_project_and_iid(project_loader, iid)
-      project_id = project_loader.__sync&.id
-
-      # IIDs are represented as the GraphQL `id` type, which is a string
-      BatchLoader.for(iid.to_s).batch(key: "merge_request:target_project:#{project_id}:iid") do |iids, loader|
-        if project_id
-          results = MergeRequest.where(target_project_id: project_id, iid: iids)
-          results.each { |mr| loader.call(mr.iid.to_s, mr) }
-        end
-      end
-    end
-  end
-end
diff --git a/app/graphql/resolvers/base_resolver.rb b/app/graphql/resolvers/base_resolver.rb
new file mode 100644
index 00000000000..89b7f9dad6f
--- /dev/null
+++ b/app/graphql/resolvers/base_resolver.rb
@@ -0,0 +1,4 @@
+module Resolvers
+  class BaseResolver < GraphQL::Schema::Resolver
+  end
+end
diff --git a/app/graphql/loaders/full_path_loader.rb b/app/graphql/resolvers/full_path_resolver.rb
index 27ada90b82a..4eb28aaed6c 100644
--- a/app/graphql/loaders/full_path_loader.rb
+++ b/app/graphql/resolvers/full_path_resolver.rb
@@ -1,13 +1,11 @@
-module Loaders::FullPathLoader
-  include Loaders::BaseLoader
+module Resolvers
+  module FullPathResolver
+    extend ActiveSupport::Concern
 
-  class << self
-    def project(obj, args, ctx)
-      project_by_full_path(args[:full_path])
-    end
-
-    def project_by_full_path(full_path)
-      model_by_full_path(Project, full_path)
+    prepended do
+      argument :full_path, GraphQL::ID_TYPE,
+               required: true,
+               description: 'The full path of the project or namespace, e.g., "gitlab-org/gitlab-ce"'
     end
 
     def model_by_full_path(model, full_path)
diff --git a/app/graphql/resolvers/merge_request_resolver.rb b/app/graphql/resolvers/merge_request_resolver.rb
new file mode 100644
index 00000000000..b1857ab09f7
--- /dev/null
+++ b/app/graphql/resolvers/merge_request_resolver.rb
@@ -0,0 +1,21 @@
+module Resolvers
+  class MergeRequestResolver < BaseResolver
+    prepend FullPathResolver
+
+    type Types::ProjectType, null: true
+
+    argument :iid, GraphQL::ID_TYPE,
+             required: true,
+             description: 'The IID of the merge request, e.g., "1"'
+
+    def resolve(full_path:, iid:)
+      project = model_by_full_path(Project, full_path)
+      return unless project.present?
+
+      BatchLoader.for(iid.to_s).batch(key: project.id) do |iids, loader|
+        results = project.merge_requests.where(iid: iids)
+        results.each { |mr| loader.call(mr.iid.to_s, mr) }
+      end
+    end
+  end
+end
diff --git a/app/graphql/resolvers/project_resolver.rb b/app/graphql/resolvers/project_resolver.rb
new file mode 100644
index 00000000000..ec115bad896
--- /dev/null
+++ b/app/graphql/resolvers/project_resolver.rb
@@ -0,0 +1,11 @@
+module Resolvers
+  class ProjectResolver < BaseResolver
+    prepend FullPathResolver
+
+    type Types::ProjectType, null: true
+
+    def resolve(full_path:)
+      model_by_full_path(Project, full_path)
+    end
+  end
+end
diff --git a/app/graphql/types/base_enum.rb b/app/graphql/types/base_enum.rb
new file mode 100644
index 00000000000..b45a845f74f
--- /dev/null
+++ b/app/graphql/types/base_enum.rb
@@ -0,0 +1,4 @@
+module Types
+  class BaseEnum < GraphQL::Schema::Enum
+  end
+end
diff --git a/app/graphql/types/base_field.rb b/app/graphql/types/base_field.rb
new file mode 100644
index 00000000000..c5740a334d7
--- /dev/null
+++ b/app/graphql/types/base_field.rb
@@ -0,0 +1,5 @@
+module Types
+  class BaseField < GraphQL::Schema::Field
+    prepend Gitlab::Graphql::Authorize
+  end
+end
diff --git a/app/graphql/types/base_input_object.rb b/app/graphql/types/base_input_object.rb
new file mode 100644
index 00000000000..309e336e6c8
--- /dev/null
+++ b/app/graphql/types/base_input_object.rb
@@ -0,0 +1,4 @@
+module Types
+  class BaseInputObject < GraphQL::Schema::InputObject
+  end
+end
diff --git a/app/graphql/types/base_interface.rb b/app/graphql/types/base_interface.rb
new file mode 100644
index 00000000000..69e72dc5808
--- /dev/null
+++ b/app/graphql/types/base_interface.rb
@@ -0,0 +1,5 @@
+module Types
+  module BaseInterface
+    include GraphQL::Schema::Interface
+  end
+end
diff --git a/app/graphql/types/base_object.rb b/app/graphql/types/base_object.rb
new file mode 100644
index 00000000000..e033ef96ce9
--- /dev/null
+++ b/app/graphql/types/base_object.rb
@@ -0,0 +1,7 @@
+module Types
+  class BaseObject < GraphQL::Schema::Object
+    prepend Gitlab::Graphql::Present
+
+    field_class Types::BaseField
+  end
+end
diff --git a/app/graphql/types/base_scalar.rb b/app/graphql/types/base_scalar.rb
new file mode 100644
index 00000000000..c0aa38be239
--- /dev/null
+++ b/app/graphql/types/base_scalar.rb
@@ -0,0 +1,4 @@
+module Types
+  class BaseScalar < GraphQL::Schema::Scalar
+  end
+end
diff --git a/app/graphql/types/base_union.rb b/app/graphql/types/base_union.rb
new file mode 100644
index 00000000000..36337fc6ee5
--- /dev/null
+++ b/app/graphql/types/base_union.rb
@@ -0,0 +1,4 @@
+module Types
+  class BaseUnion < GraphQL::Schema::Union
+  end
+end
diff --git a/app/graphql/types/merge_request_type.rb b/app/graphql/types/merge_request_type.rb
index fc430ca03d5..d5d24952984 100644
--- a/app/graphql/types/merge_request_type.rb
+++ b/app/graphql/types/merge_request_type.rb
@@ -1,46 +1,47 @@
-Types::MergeRequestType = GraphQL::ObjectType.define do
-  present_using MergeRequestPresenter
+module Types
+  class MergeRequestType < BaseObject
+    present_using MergeRequestPresenter
 
-  name 'MergeRequest'
+    graphql_name 'MergeRequest'
 
-  field :id, !types.ID
-  field :iid, !types.ID
-  field :title, !types.String
-  field :description, types.String
-  field :state, types.String
-  field :created_at, !Types::TimeType
-  field :updated_at, !Types::TimeType
-  field :source_project, Types::ProjectType
-  field :target_project, !Types::ProjectType
-  # Alias for target_project
-  field :project, !Types::ProjectType
-  field :project_id, !types.Int, property: :target_project_id
-  field :source_project_id, types.Int
-  field :target_project_id, !types.Int
-  field :source_branch, !types.String
-  field :target_branch, !types.String
-  field :work_in_progress, types.Boolean, property: :work_in_progress?
-  field :merge_when_pipeline_succeeds, types.Boolean
-  field :sha, types.String, property: :diff_head_sha
-  field :merge_commit_sha, types.String
-  field :user_notes_count, types.Int
-  field :should_remove_source_branch, types.Boolean, property: :should_remove_source_branch?
-  field :force_remove_source_branch, types.Boolean, property: :force_remove_source_branch?
-  field :merge_status, types.String
-  field :in_progress_merge_commit_sha, types.String
-  field :merge_error, types.String
-  field :allow_maintainer_to_push, types.Boolean
-  field :should_be_rebased, types.Boolean, property: :should_be_rebased?
-  field :rebase_commit_sha, types.String
-  field :rebase_in_progress, types.Boolean, property: :rebase_in_progress?
-  field :diff_head_sha, types.String
-  field :merge_commit_message, types.String
-  field :merge_ongoing, types.Boolean, property: :merge_ongoing?
-  field :work_in_progress, types.Boolean, property: :work_in_progress?
-  field :source_branch_exists, types.Boolean, property: :source_branch_exists?
-  field :mergeable_discussions_state, types.Boolean
-  field :web_url, types.String, property: :web_url
-  field :upvotes, types.Int
-  field :downvotes, types.Int
-  field :subscribed, types.Boolean, property: :subscribed?
+    field :id, GraphQL::ID_TYPE, null: false
+    field :iid, GraphQL::ID_TYPE, null: false
+    field :title, GraphQL::STRING_TYPE, null: false
+    field :description, GraphQL::STRING_TYPE, null: true
+    field :state, GraphQL::STRING_TYPE, null: true
+    field :created_at, Types::TimeType, null: false
+    field :updated_at, Types::TimeType, null: false
+    field :source_project, Types::ProjectType, null: true
+    field :target_project, Types::ProjectType, null: false
+    # Alias for target_project
+    field :project, Types::ProjectType, null: false
+    field :project_id, GraphQL::INT_TYPE, null: false, method: :target_project_id
+    field :source_project_id, GraphQL::INT_TYPE, null: true
+    field :target_project_id, GraphQL::INT_TYPE, null: false
+    field :source_branch, GraphQL::STRING_TYPE, null: false
+    field :target_branch, GraphQL::STRING_TYPE, null: false
+    field :work_in_progress, GraphQL::BOOLEAN_TYPE, method: :work_in_progress?, null: false
+    field :merge_when_pipeline_succeeds, GraphQL::BOOLEAN_TYPE, null: true
+    field :diff_head_sha, GraphQL::STRING_TYPE, null: true
+    field :merge_commit_sha, GraphQL::STRING_TYPE, null: true
+    field :user_notes_count, GraphQL::INT_TYPE, null: true
+    field :should_remove_source_branch, GraphQL::BOOLEAN_TYPE, method: :should_remove_source_branch?, null: true
+    field :force_remove_source_branch, GraphQL::BOOLEAN_TYPE, method: :force_remove_source_branch?, null: true
+    field :merge_status, GraphQL::STRING_TYPE, null: true
+    field :in_progress_merge_commit_sha, GraphQL::STRING_TYPE, null: true
+    field :merge_error, GraphQL::STRING_TYPE, null: true
+    field :allow_collaboration, GraphQL::BOOLEAN_TYPE, null: true
+    field :should_be_rebased, GraphQL::BOOLEAN_TYPE, method: :should_be_rebased?, null: false
+    field :rebase_commit_sha, GraphQL::STRING_TYPE, null: true
+    field :rebase_in_progress, GraphQL::BOOLEAN_TYPE, method: :rebase_in_progress?, null: false
+    field :diff_head_sha, GraphQL::STRING_TYPE, null: true
+    field :merge_commit_message, GraphQL::STRING_TYPE, null: true
+    field :merge_ongoing, GraphQL::BOOLEAN_TYPE, method: :merge_ongoing?, null: false
+    field :source_branch_exists, GraphQL::BOOLEAN_TYPE, method: :source_branch_exists?, null: false
+    field :mergeable_discussions_state, GraphQL::BOOLEAN_TYPE, null: true
+    field :web_url, GraphQL::STRING_TYPE, null: true
+    field :upvotes, GraphQL::INT_TYPE, null: false
+    field :downvotes, GraphQL::INT_TYPE, null: false
+    field :subscribed, GraphQL::BOOLEAN_TYPE, method: :subscribed?, null: false
+  end
 end
diff --git a/app/graphql/types/mutation_type.rb b/app/graphql/types/mutation_type.rb
index c5061f10239..06ed91c1658 100644
--- a/app/graphql/types/mutation_type.rb
+++ b/app/graphql/types/mutation_type.rb
@@ -1,5 +1,7 @@
-Types::MutationType = GraphQL::ObjectType.define do
-  name "Mutation"
+module Types
+  class MutationType < BaseObject
+    graphql_name "Mutation"
 
-  # TODO: Add Mutations as fields
+    # TODO: Add Mutations as fields
+  end
 end
diff --git a/app/graphql/types/project_type.rb b/app/graphql/types/project_type.rb
index 593c1b67830..9e885d5845a 100644
--- a/app/graphql/types/project_type.rb
+++ b/app/graphql/types/project_type.rb
@@ -1,63 +1,65 @@
-Types::ProjectType = GraphQL::ObjectType.define do
-  name 'Project'
+module Types
+  class ProjectType < BaseObject
+    graphql_name 'Project'
 
-  field :id, !types.ID
+    field :id, GraphQL::ID_TYPE, null: false
 
-  field :full_path, !types.ID
-  field :path, !types.String
+    field :full_path, GraphQL::ID_TYPE, null: false
+    field :path, GraphQL::STRING_TYPE, null: false
 
-  field :name_with_namespace, !types.String
-  field :name, !types.String
+    field :name_with_namespace, GraphQL::STRING_TYPE, null: false
+    field :name, GraphQL::STRING_TYPE, null: false
 
-  field :description, types.String
+    field :description, GraphQL::STRING_TYPE, null: true
 
-  field :default_branch, types.String
-  field :tag_list, types.String
+    field :default_branch, GraphQL::STRING_TYPE, null: true
+    field :tag_list, GraphQL::STRING_TYPE, null: true
 
-  field :ssh_url_to_repo, types.String
-  field :http_url_to_repo, types.String
-  field :web_url, types.String
+    field :ssh_url_to_repo, GraphQL::STRING_TYPE, null: true
+    field :http_url_to_repo, GraphQL::STRING_TYPE, null: true
+    field :web_url, GraphQL::STRING_TYPE, null: true
 
-  field :star_count, !types.Int
-  field :forks_count, !types.Int
+    field :star_count, GraphQL::INT_TYPE, null: false
+    field :forks_count, GraphQL::INT_TYPE, null: false
 
-  field :created_at, Types::TimeType
-  field :last_activity_at, Types::TimeType
+    field :created_at, Types::TimeType, null: true
+    field :last_activity_at, Types::TimeType, null: true
 
-  field :archived, types.Boolean
+    field :archived, GraphQL::BOOLEAN_TYPE, null: true
 
-  field :visibility, types.String
+    field :visibility, GraphQL::STRING_TYPE, null: true
 
-  field :container_registry_enabled, types.Boolean
-  field :shared_runners_enabled, types.Boolean
-  field :lfs_enabled, types.Boolean
-  field :ff_only_enabled, types.Boolean, property: :merge_requests_ff_only_enabled
+    field :container_registry_enabled, GraphQL::BOOLEAN_TYPE, null: true
+    field :shared_runners_enabled, GraphQL::BOOLEAN_TYPE, null: true
+    field :lfs_enabled, GraphQL::BOOLEAN_TYPE, null: true
+    field :merge_requests_ff_only_enabled, GraphQL::BOOLEAN_TYPE, null: true
 
-  field :avatar_url, types.String do
-    resolve ->(project, args, ctx) { project.avatar_url(only_path: false) }
-  end
+    field :avatar_url, GraphQL::STRING_TYPE, null: true, resolve: -> (project, args, ctx) do
+      project.avatar_url(only_path: false)
+    end
 
-  %i[issues merge_requests wiki snippets].each do |feature|
-    field "#{feature}_enabled", types.Boolean do
-      resolve ->(project, args, ctx) { project.feature_available?(feature, ctx[:current_user]) }
+    %i[issues merge_requests wiki snippets].each do |feature|
+      field "#{feature}_enabled", GraphQL::BOOLEAN_TYPE, null: true, resolve: -> (project, args, ctx) do
+        project.feature_available?(feature, ctx[:current_user])
+      end
     end
-  end
 
-  field :jobs_enabled, types.Boolean do
-    resolve ->(project, args, ctx) { project.feature_available?(:builds, ctx[:current_user]) }
-  end
+    field :jobs_enabled, GraphQL::BOOLEAN_TYPE, null: true, resolve: -> (project, args, ctx) do
+      project.feature_available?(:builds, ctx[:current_user])
+    end
 
-  field :public_jobs, types.Boolean, property: :public_builds
+    field :public_jobs, GraphQL::BOOLEAN_TYPE, method: :public_builds, null: true
 
-  field :open_issues_count, types.Int do
-    resolve ->(project, args, ctx) { project.open_issues_count if project.feature_available?(:issues, ctx[:current_user]) }
-  end
+    field :open_issues_count, GraphQL::INT_TYPE, null: true, resolve: -> (project, args, ctx) do
+      project.open_issues_count if project.feature_available?(:issues, ctx[:current_user])
+    end
 
-  field :import_status, types.String
-  field :ci_config_path, types.String
+    field :import_status, GraphQL::STRING_TYPE, null: true
+    field :ci_config_path, GraphQL::STRING_TYPE, null: true
 
-  field :only_allow_merge_if_pipeline_succeeds, types.Boolean
-  field :request_access_enabled, types.Boolean
-  field :only_allow_merge_if_all_discussions_are_resolved, types.Boolean
-  field :printing_merge_request_link_enabled, types.Boolean
+    field :only_allow_merge_if_pipeline_succeeds, GraphQL::BOOLEAN_TYPE, null: true
+    field :request_access_enabled, GraphQL::BOOLEAN_TYPE, null: true
+    field :only_allow_merge_if_all_discussions_are_resolved, GraphQL::BOOLEAN_TYPE, null: true
+    field :printing_merge_request_link_enabled, GraphQL::BOOLEAN_TYPE, null: true
+  end
 end
diff --git a/app/graphql/types/query_type.rb b/app/graphql/types/query_type.rb
index 029bbd098ad..be79c78bf67 100644
--- a/app/graphql/types/query_type.rb
+++ b/app/graphql/types/query_type.rb
@@ -1,38 +1,21 @@
-Types::QueryType = GraphQL::ObjectType.define do
-  name 'Query'
-
-  field :project, Types::ProjectType do
-    argument :full_path, !types.ID do
-      description 'The full path of the project, e.g., "gitlab-org/gitlab-ce"'
-    end
-
-    authorize :read_project
-
-    resolve Loaders::FullPathLoader[:project]
-  end
-
-  field :merge_request, Types::MergeRequestType do
-    argument :project, !types.ID do
-      description 'The full path of the target project, e.g., "gitlab-org/gitlab-ce"'
+module Types
+  class QueryType < BaseObject
+    graphql_name 'Query'
+
+    field :project, Types::ProjectType,
+          null: true,
+          resolver: Resolvers::ProjectResolver,
+          description: "Find a project" do
+      authorize :read_project
     end
 
-    argument :iid, !types.ID do
-      description 'The IID of the merge request, e.g., "1"'
+    field :merge_request, Types::MergeRequestType,
+          null: true,
+          resolver: Resolvers::MergeRequestResolver,
+          description: "Find a merge request" do
+      authorize :read_merge_request
     end
 
-    authorize :read_merge_request
-
-    resolve Loaders::IidLoader[:merge_request]
-  end
-
-  # Testing endpoint to validate the API with
-  field :echo, types.String do
-    argument :text, types.String
-
-    resolve -> (obj, args, ctx) do
-      username = ctx[:current_user]&.username
-
-      "#{username.inspect} says: #{args[:text]}"
-    end
+    field :echo, GraphQL::STRING_TYPE, null: false, function: Functions::Echo.new
   end
 end
diff --git a/app/graphql/types/time_type.rb b/app/graphql/types/time_type.rb
index fb717eb3dc7..2333d82ad1e 100644
--- a/app/graphql/types/time_type.rb
+++ b/app/graphql/types/time_type.rb
@@ -1,8 +1,14 @@
-# Taken from http://www.rubydoc.info/github/rmosolgo/graphql-ruby/GraphQL/ScalarType
-Types::TimeType = GraphQL::ScalarType.define do
-  name 'Time'
-  description 'Time since epoch in fractional seconds'
+module Types
+  class TimeType < BaseScalar
+    graphql_name 'Time'
+    description 'Time represented in ISO 8601'
 
-  coerce_input ->(value, ctx) { Time.at(Float(value)) }
-  coerce_result ->(value, ctx) { value.to_f }
+    def self.coerce_input(value, ctx)
+      Time.parse(value)
+    end
+
+    def self.coerce_result(value, ctx)
+      value.iso8601
+    end
+  end
 end