1 files changed, 11 insertions, 1 deletions
diff --git a/src/new_fields/Doc.ts b/src/new_fields/Doc.ts
index 092205f52..aa13b1d7a 100644
--- a/src/new_fields/Doc.ts
+++ b/src/new_fields/Doc.ts
@@ -9,6 +9,7 @@ import { ObjectField } from "./ObjectField";
 import { RefField, FieldId } from "./RefField";
 import { ToScriptString, SelfProxy, Parent, OnUpdate, Self, HandleUpdate, Update, Id } from "./FieldSymbols";
 import { scriptingGlobal } from "../client/util/Scripting";
+import { List } from "./List";
 
 export namespace Field {
     export function toScriptString(field: Field): string {
@@ -241,9 +242,18 @@ export namespace Doc {
         return Array.from(results);
     }
 
-    export function AddDocToList(target: Doc, key: string, doc: Doc, relativeTo?: Doc, before?: boolean, first?: boolean) {
+    export function AddDocToList(target: Doc, key: string, doc: Doc, relativeTo?: Doc, before?: boolean, first?: boolean, allowDuplicates?: boolean) {
+        if (target[key] === undefined) {
+            Doc.GetProto(target)[key] = new List<Doc>();
+        }
         let list = Cast(target[key], listSpec(Doc));
         if (list) {
+            if (allowDuplicates !== true) {
+                let pind = list.reduce((l, d, i) => d instanceof Doc && Doc.AreProtosEqual(d, doc) ? i : l, -1);
+                if (pind !== -1) {
+                    list.splice(pind, 1);
+                }
+            }
             if (first) list.splice(0, 0, doc);
             else {
                 let ind = relativeTo ? list.indexOf(relativeTo) : -1;