How to call the refreshing of data-aware (live-binding) component in FireMonkey?

Question

I have a TListView linked in LiveBindings with a TFDMemTable . I load data in the FDMemTable using LoadFromFile (I have for example 20 record).

When I delete a record from the FDMemTable, the RecordCount is decreased but the TListView is not refreshed, it continue to display the 20 records loaded on the LoadFormFile .

If, with the FDMemTable: I .SaveToFile , .Close , and reload with .LoadFromFile , the TListView now display the change.

This is the same behavior if I use the CachedUpdate of FDMemTable or not.

I've tried to call TFDMemTable.Refresh and TListView.Repaint without succes.

Is it possible to call the TListView to refresh his "linked" set of data ?

When I delete a record in the FDMemTable, why no visible refresh occur on the TListView ?

EDIT: I must add a thing, the record is deleted programmatically.

The desired functionality is to delete sone unwanted record in the FDMemTable and display the remaining record to the user with the TListView .

Answer 1

In LiveBindings Designer, by linking the Synch of the ListView to the * of the FDMemTable , the ListView now display the resulting record.

Also in my last algorithm, because I use .BeginBatch / .EndBatch (that disable data-aware refreshing), while processing data for removing unwanted record I've to disable the LiveBinding link temporarily (cause I use different sorting index whitin the processing of the data): LinkListControlToField1.Active := false; and "re-link" it after processing: LinkListControlToField1.Active := true;

Answer 2

The livebindings isn't consistently bi-directional here. The ListView livebindings was designed to work from the UI to the dataset direction, but only mostly.

If you enable CanSwipeDelete , you can expect that to work, if you know how.

In my case, on Android, I found myself writing code to ensure that the listview kept sync with the dataset, even though there is livebindings active. In my case is a TClientDataset named CDSAnimals, with a unique key value of TagID. I hope this helps.

procedure TfrmLiveMain.ListView1DeletingItem(Sender: TObject; AIndex: Integer;
  var ACanDelete: Boolean);
var
  LI: TListViewItem;
  LIO: TListItemText;
begin

  // check that the livebindings is doing it's job, if not
  // do it myself
  ACanDelete := False;
  LI := ListView1.Items[AIndex];
  LIO := LI.Objects.FindObjectT<TListItemText>('Text1');
  FTagID := LIO.Text;
  if ClientModule2.CDSAnimals.FieldByName('TagID').AsString <> FTagID then
    ClientModule2.CDSAnimals.Locate('TagID', FTagID, []);
  if ClientModule2.CDSAnimals.FieldByName('TagID').AsString = FTagID then
  begin
    ACanDelete := True; // causes the listview item to be deleted without
                        // affecting the corresponding dataset record
  end;

end;

procedure TfrmLiveMain.ListView1DeleteItem(Sender: TObject; AIndex: Integer);
begin

  // this is called with the wrong index!
  if ClientModule2.CDSAnimals.Locate('TagID', FTagID, []) then
    if ClientModule2.CDSAnimals.FieldByName('TagID').AsString = FTagID then
      begin
        // now delete the corresponding record too
        ClientModule2.CDSAnimals.Delete; // and it works!
      end;

end;