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TWebClientDataSet.GetPendingUpdates

WEB TMS WEB Core
#1

I did not find documentation and no sample, so I would appreciate some assistance.

For testing purposes I created a simple form, added a TWebClientDataSet and inserted some records. In the real app, data comes from a REST service , gets edited and should be written back. So I need access to the changes.

This is what I tried:

procedure TForm2.btnInsertClick(Sender: TObject);
var
  n: Integer;
begin
  n := cdsData.RecordCount + 1;
  cdsData.InsertRecord([n, 'zeile1']);
end;

procedure TForm2.btnGetUpdatesClick(Sender: TObject);
var
  i: Integer;
  resArray: TResolveinfoArray;
  s: string;
  Info: PTypeInfo;
begin
  Info := System.TypeInfo(TUpdateStatus);
  resArray := cdsData.GetPendingUpdates;
  for i := 0 to High(resArray) - 1 do  begin
    s:='';
    s:=s+'Status '+GetEnumName(Info,ord(resArray[i].Status));
  // log all data here
   ShowMessage(s);
  end;
end;

However, PendingUpdates is nil. Looking at the source:

function TWebCustomClientDataSet.GetPendingUpdates: TResolveInfoArray;
begin
  Result := nil;
end;

So, I think I am missing something basically here.

BTW: TJSValue - how do I access these values or how to comvert this?

Thanks a lot!
Bernd

#2

I suspect you look at the design-time code.

The runtime GetPendingUpdates is in Core Source\RTL\DB.pas defined for base class TDataSet and it is not returning nil but a TResolveInfoArray.

#3

Ups. My fault.
Still my question is: Why is the TResolveInfoArry nil in this case and how do I get access to the changes?

#4

To be precise, ResolveInfoArry is not nil, the GetpendingUpdates throws an error

 ERROR
TypeError: this.FChangeList is null | this.GetRecordUpdates@http://localhost:8000/projGetPendingUpdates/projGetPendingUpdates.js:77919:38 this.GetPendingUpdates@http://localhost:8000/projGetPendingUpdates/projGetPendingUpdates.js:79409:67 this.btnUpdatesClick@http://localhost:8000/projGetPendingUpdates/projGetPendingUpdates.js:108219:31 cb@http://localhost:8000/projGetPendingUpdates/projGetPendingUpdates.js:245:19 this.Click@http://localhost:8000/projGetPendingUpdates/projGetPendingUpdates.js:29776:61 this.HandleDoClick@http://localhost:8000/projGetPendingUpdates/projGetPendingUpdates.js:29265:31 cb@http://localhost:8000/projGetPendingUpdates/projGetPendingUpdates.js:241:26
at http://localhost:8000/projGetPendingUpdates/projGetPendingUpdates.js [77919:38]
#5

I cannot reproduce a problem.
Test applied on demo Demo\Basics\Dataset with code:

procedure TForm1.WebButton2Click(Sender: TObject);
var
  ar: TResolveInfoArray;
  i: integer;
begin
  ar := webclientdataset1.GetPendingUpdates;
  for I := 0 to length(ar) - 1 do
  begin
    console.log(ar[i]);
  end;
end;

shows after 2 edits in the console:

image
image731×325 32.5 KB

#6

For me this does not even compile, because the concole.log needs a TJSValue, so this compiles for me:
console.log(resArray[i].Data);

However I have attached my demo, maybe this helps you to point out what I am missing.

Thank you very much, Bruno!
projGetPendingUpdates.zip (7.8 KB)

#7

Issue is caused by this dataset having no client connection, hence no dataproxy.
We'll check this with the pas2js team as this is in the DB RTL. Meanwhile, we implemented a workaround that will be in the next beta.

#8

I see. Thank´s for verifying.

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