1 files changed, 30 insertions, 0 deletions
diff --git a/app/graphql/mutations/merge_requests/set_milestone.rb b/app/graphql/mutations/merge_requests/set_milestone.rb
new file mode 100644
index 00000000000..707d6677952
--- /dev/null
+++ b/app/graphql/mutations/merge_requests/set_milestone.rb
@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+module Mutations
+  module MergeRequests
+    class SetMilestone < Base
+      graphql_name 'MergeRequestSetMilestone'
+
+      argument :milestone_id,
+               GraphQL::ID_TYPE,
+               required: false,
+               loads: Types::MilestoneType,
+               description: <<~DESC
+                            The milestone to assign to the merge request.
+               DESC
+
+      def resolve(project_path:, iid:, milestone: nil)
+        merge_request = authorized_find!(project_path: project_path, iid: iid)
+        project = merge_request.project
+
+        ::MergeRequests::UpdateService.new(project, current_user, milestone: milestone)
+          .execute(merge_request)
+
+        {
+          merge_request: merge_request,
+          errors: merge_request.errors.full_messages
+        }
+      end
+    end
+  end
+end