Merge branch 'bvl-graphql-start-34754' into 'master'

GraphQL setup: Basic Project and Merge request endpoint

Closes #34754

See merge request gitlab-org/gitlab-ce!19008

Gemfile

@@ -93,6 +93,10 @@ gem 'grape', '~> 1.0'
 gem 'grape-entity', '~> 0.7.1'
 gem 'rack-cors', '~> 1.0.0', require: 'rack/cors'
+# GraphQL API
+gem 'graphql', '~> 1.8.0'
+gem 'graphiql-rails', '~> 1.4.10'
+
 # Disable strong_params so that Mash does not respond to :permitted?
 gem 'hashie-forbidden_attributes'

Gemfile.lock

@@ -365,6 +365,10 @@ GEM
       rake (~> 12)
     grape_logging (1.7.0)
       grape
+    graphiql-rails (1.4.10)
+      railties
+      sprockets-rails
+    graphql (1.8.1)
     grpc (1.11.0)
       google-protobuf (~> 3.1)
       googleapis-common-protos-types (~> 1.0.0)
@@ -1053,6 +1057,8 @@ DEPENDENCIES
   grape-entity (~> 0.7.1)
   grape-path-helpers (~> 1.0)
   grape_logging (~> 1.7)
+  graphiql-rails (~> 1.4.10)
+  graphql (~> 1.8.0)
   grpc (~> 1.11.0)
   haml_lint (~> 0.26.0)
   hamlit (~> 2.6.1)

app/controllers/graphql_controller.rb

+class GraphqlController < ApplicationController
+  # Unauthenticated users have access to the API for public data
+  skip_before_action :authenticate_user!
+
+  before_action :check_graphql_feature_flag!
+
+  def execute
+    variables = Gitlab::Graphql::Variables.new(params[:variables]).to_h
+    query = params[:query]
+    operation_name = params[:operationName]
+    context = {
+      current_user: current_user
+    }
+    result = GitlabSchema.execute(query, variables: variables, context: context, operation_name: operation_name)
+    render json: result
+  end
+
+  rescue_from StandardError do |exception|
+    log_exception(exception)
+
+    render_error("Internal server error")
+  end
+
+  rescue_from Gitlab::Graphql::Variables::Invalid do |exception|
+    render_error(exception.message, status: :unprocessable_entity)
+  end
+
+  private
+
+  # Overridden from the ApplicationController to make the response look like
+  # a GraphQL response. That is nicely picked up in Graphiql.
+  def render_404
+    render_error("Not found!", status: :not_found)
+  end
+
+  def render_error(message, status: 500)
+    error = { errors: [message: message] }
+
+    render json: error, status: status
+  end
+
+  def check_graphql_feature_flag!
+    render_404 unless Feature.enabled?(:graphql)
+  end
+end

app/graphql/functions/base_function.rb

+module Functions
+  class BaseFunction < GraphQL::Function
+  end
+end

app/graphql/functions/echo.rb

+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

app/graphql/gitlab_schema.rb

+class GitlabSchema < GraphQL::Schema
+  use BatchLoader::GraphQL
+  use Gitlab::Graphql::Authorize
+  use Gitlab::Graphql::Present
+
+  query(Types::QueryType)
+  # mutation(Types::MutationType)
+end

app/graphql/resolvers/base_resolver.rb

+module Resolvers
+  class BaseResolver < GraphQL::Schema::Resolver
+  end
+end

app/graphql/resolvers/full_path_resolver.rb

+module Resolvers
+  module FullPathResolver
+    extend ActiveSupport::Concern
+
+    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)
+      BatchLoader.for(full_path).batch(key: "#{model.model_name.param_key}:full_path") do |full_paths, loader|
+        # `with_route` avoids an N+1 calculating full_path
+        results = model.where_full_path_in(full_paths).with_route
+        results.each { |project| loader.call(project.full_path, project) }
+      end
+    end
+  end
+end

app/graphql/resolvers/merge_request_resolver.rb

+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

app/graphql/resolvers/project_resolver.rb

+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

app/graphql/types/base_enum.rb

+module Types
+  class BaseEnum < GraphQL::Schema::Enum
+  end
+end

app/graphql/types/base_field.rb

+module Types
+  class BaseField < GraphQL::Schema::Field
+    prepend Gitlab::Graphql::Authorize
+  end
+end

app/graphql/types/base_input_object.rb

+module Types
+  class BaseInputObject < GraphQL::Schema::InputObject
+  end
+end

app/graphql/types/base_interface.rb

+module Types
+  module BaseInterface
+    include GraphQL::Schema::Interface
+  end
+end

app/graphql/types/base_object.rb

+module Types
+  class BaseObject < GraphQL::Schema::Object
+    prepend Gitlab::Graphql::Present
+
+    field_class Types::BaseField
+  end
+end

app/graphql/types/base_scalar.rb

+module Types
+  class BaseScalar < GraphQL::Schema::Scalar
+  end
+end

app/graphql/types/base_union.rb

+module Types
+  class BaseUnion < GraphQL::Schema::Union
+  end
+end

app/graphql/types/merge_request_type.rb

+module Types
+  class MergeRequestType < BaseObject
+    present_using MergeRequestPresenter
+
+    graphql_name 'MergeRequest'
+
+    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

app/graphql/types/mutation_type.rb

+module Types
+  class MutationType < BaseObject
+    graphql_name "Mutation"
+
+    # TODO: Add Mutations as fields
+  end
+end