1 files changed, 50 insertions, 0 deletions
diff --git a/app/graphql/types/work_item_id_type.rb b/app/graphql/types/work_item_id_type.rb
new file mode 100644
index 00000000000..ddcf3416014
--- /dev/null
+++ b/app/graphql/types/work_item_id_type.rb
@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+module Types
+  # rubocop:disable Graphql/AuthorizeTypes
+  # TODO: This type should be removed when Work Items become generally available.
+  # This mechanism is introduced temporarily to make the client implementation easier during this transition.
+  class WorkItemIdType < GlobalIDType
+    graphql_name 'WorkItemID'
+    description <<~DESC
+      A `WorkItemID` is a global ID. It is encoded as a string.
+
+      An example `WorkItemID` is: `"gid://gitlab/WorkItem/1"`.
+
+      While we transition from Issues into Work Items this type will temporarily support
+      `IssueID` like: `"gid://gitlab/Issue/1"`. This behavior will be removed without notice in the future.
+    DESC
+
+    class << self
+      def coerce_result(gid, ctx)
+        global_id = ::Gitlab::GlobalId.as_global_id(gid, model_name: 'WorkItem')
+
+        raise GraphQL::CoercionError, "Expected a WorkItem ID, got #{global_id}" unless suitable?(global_id)
+
+        # Always return a WorkItemID even if an Issue is returned by a resolver
+        work_item_gid(global_id).to_s
+      end
+
+      def coerce_input(string, ctx)
+        gid = super
+        # Always return a WorkItemID even if an Issue Global ID is provided as input
+        return work_item_gid(gid) if suitable?(gid)
+
+        raise GraphQL::CoercionError, "#{string.inspect} does not represent an instance of WorkItem"
+      end
+
+      def suitable?(gid)
+        return false if gid&.model_name&.safe_constantize.blank?
+
+        [::WorkItem, ::Issue].any? { |model_class| gid.model_class == model_class }
+      end
+
+      private
+
+      def work_item_gid(gid)
+        GlobalID.new(::Gitlab::GlobalId.build(model_name: 'WorkItem', id: gid.model_id))
+      end
+    end
+  end
+  # rubocop:enable Graphql/AuthorizeTypes
+end