* Merging revisions 915 from trunk:

    ------------------------------------------------------------------------
    r915 | michael | 2020-11-05 09:34:37 +0100 (Thu, 05 Nov 2020) | 1 line
    
    * Avoid returning undefined when getting field data
    ------------------------------------------------------------------------

packages/fcl-db/db.pas

@@ -3162,6 +3162,8 @@ function TDataSet.GetFieldData(Field: TField; Buffer: TDatarecord): JSValue;
 
 begin
   Result:=TJSObject(buffer.data).Properties[Field.FieldName];
+  if isUndefined(Result) then
+    Result:=Null;
 end;
 
 
@@ -5563,7 +5565,11 @@ begin
   If FValidating then
     result:=FValueBuffer
   else
+    begin
     Result:=FDataset.GetFieldData(Self);
+    If IsUndefined(Result) then
+      Result:=Null;
+    end;
 end;
 
 function TField.GetDataSize: Integer;

packages/fcl-db/jsondataset.pas

@@ -1698,6 +1698,8 @@ begin
       R:=Buffer.data;
     end;
   Result:=FFieldMapper.GetJSONDataForField(Field,R);
+  if isUndefined(Result) then
+    Result:=Null;
 end;
 
 procedure TBaseJSONDataSet.SetFieldData(Field: TField; var Buffer: TDatarecord; AValue : JSValue);