Add field mergeRequests for project in GraphQL

And fix the tests so that it won't run into circular paths.

1 files changed, 36 insertions, 0 deletions

diff --git a/app/graphql/resolvers/merge_requests_resolver.rb b/app/graphql/resolvers/merge_requests_resolver.rb
new file mode 100644
index 00000000000..15055db633a
--- /dev/null
+++ b/app/graphql/resolvers/merge_requests_resolver.rb
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+module Resolvers
+  class MergeRequestsResolver < BaseResolver
+    argument :iid, GraphQL::ID_TYPE,
+             required: false,
+             description: 'The IID of the merge request, e.g., "1"'
+
+    argument :iids, [GraphQL::ID_TYPE],
+              required: false,
+              description: 'The list of IIDs of issues, e.g., [1, 2]'
+
+    type Types::MergeRequestType, null: true
+
+    alias_method :project, :object
+
+    def resolve(**args)
+      return unless project.present?
+
+      args[:iids] ||= [args[:iid]]
+
+      args[:iids].map(&method(:batch_load))
+        .select(&:itself) # .compact doesn't work on BatchLoader
+    end
+
+    # rubocop: disable CodeReuse/ActiveRecord
+    def batch_load(iid)
+      BatchLoader.for(iid.to_s).batch(key: project) do |iids, loader, args|
+        args[:key].merge_requests.where(iid: iids).each do |mr|
+          loader.call(mr.iid.to_s, mr)
+        end
+      end
+    end
+    # rubocop: enable CodeReuse/ActiveRecord
+  end
+end