1 files changed, 3 insertions, 0 deletions
diff --git a/src/fields/Doc.ts b/src/fields/Doc.ts
index 460dd6081..466b43287 100644
--- a/src/fields/Doc.ts
+++ b/src/fields/Doc.ts
@@ -491,6 +491,9 @@ export namespace Doc {
     export function IsSystem(doc: Doc) {
         return GetT(doc, 'system', 'boolean', true);
     }
+    export function IsDelegateField(doc: Doc, fieldKey: string) {
+        return doc && Get(doc, fieldKey, true) !== undefined;
+    }
     export async function SetInPlace(doc: Doc, key: string, value: Field | undefined, defaultProto: boolean) {
         if (key.startsWith('_')) key = key.substring(1);
         const hasProto = doc.proto instanceof Doc;