1 files changed, 34 insertions, 0 deletions
diff --git a/lib/gitlab/graphql/present/instrumentation.rb b/lib/gitlab/graphql/present/instrumentation.rb
new file mode 100644
index 00000000000..6f2b26c9676
--- /dev/null
+++ b/lib/gitlab/graphql/present/instrumentation.rb
@@ -0,0 +1,34 @@
+module Gitlab
+  module Graphql
+    module Present
+      class Instrumentation
+        def instrument(type, field)
+          presented_in = field.metadata[:type_class].owner
+          return field unless presented_in.respond_to?(:presenter_class)
+          return field unless presented_in.presenter_class
+
+          old_resolver = field.resolve_proc
+
+          resolve_with_presenter = -> (presented_type, args, context) do
+            # We need to wrap the original presentation type into a type that
+            # uses the presenter as an object.
+            object = presented_type.object
+
+            if object.is_a?(presented_in.presenter_class)
+              next old_resolver.call(presented_type, args, context)
+            end
+
+            presenter = presented_in.presenter_class.new(object, **context.to_h)
+            wrapped = presented_type.class.new(presenter, context)
+
+            old_resolver.call(wrapped, args, context)
+          end
+
+          field.redefine do
+            resolve(resolve_with_presenter)
+          end
+        end
+      end
+    end
+  end
+end