mer con

1 files changed, 7 insertions, 1 deletions

diff --git a/src/fields/Document.ts b/src/fields/Document.ts
index 2e873439c..25e239417 100644
--- a/src/fields/Document.ts
+++ b/src/fields/Document.ts
@@ -1,6 +1,6 @@
 import { Key } from "./Key"
 import { KeyStore } from "./KeyStore";
-import { Field, Cast, FieldWaiting, FieldValue, FieldId } from "./Field"
+import { Field, Cast, FieldWaiting, FieldValue, FieldId, Opt } from "./Field"
 import { NumberField } from "./NumberField";
 import { ObservableMap, computed, action } from "mobx";
 import { TextField } from "./TextField";
@@ -128,6 +128,12 @@ export class Document extends Field {
         return false;
     }
 
+    GetTAsync<T extends Field>(key: Key, ctor: { new(): T }, callback: (field: Opt<T>) => void): boolean {
+        return this.GetAsync(key, (field) => {
+            callback(Cast(field, ctor));
+        })
+    }
+
     /**
      * Same as {@link Document#GetAsync}, except a field of the given type
      * will be created if there is no field associated with the given key,