TStringGrid ComboBox not updating dataset

[TrevorS 3]

Type THelpModel = Class(TGridModel);

procedure TViewPart.ChangeStringGridComboBoxCurrency(Sender: TObject);
begin
  with TComboBox(Sender), StringGridPartDet 
   do begin
    THelpModel(StringGridPartDet.Columns[2].Model).DoSetValue(Col,Row, TValue.From<String>(Items[ItemIndex]) );
    StringGridPartDet.Columns[2].UpdateCell(Row);
   end;
end;

procedure TViewPart.StringGridPartDetCreateCustomEditor(Sender: TObject;
  const Column: TColumn; var Control: TStyledControl);
begin
  if Column = StringGridPartDet.Columns[2] 
   then begin
     Control := TComboBox.Create(Self);
     TComboBox(Control).Items.AddStrings(['GBP', 'EUR']);
     With StringGridPartDet, TComboBox(Control) do
       ItemIndex := Items.IndexOf(THelpModel(StringGridPartDet.Columns[2].Model).DoGetValue(Col,Row).AsString);
     TComboBox(Control).OnChange:= ChangeStringGridComboBoxCurrency;
   end;
end;

I have a StringGrid (StringGridPartDet)  connected to a DataSet, I have used the attached code to update the currency column with a value from a ComboBox, the value appears correctly in the StringGrid, but does not update the DataSet. AmI missing a step?

 

 

 

[programmerdelphi2k 237]

try this...

// my sample in FMX project
AGridOrStringGrid.BeginUpdate;
  try
    TMyHackTGridModel(AGridOrStringGrid.Model).DoSetValue(ACol, ARow, AValue); // calls OnSetValue(...);
    //
    AGridOrStringGrid.Model.PostEditorValue;  // <---- all rest is done by "Model" if datasource is your table, etc...
    //
  finally
    AGridOrStringGrid.EndUpdate;
  end;

 

Edited March 10, 2023 by programmerdelphi2k

[TrevorS 3]

Thanks for your suggestion, but the behaviour remains the same - the grid updates correctly, but not the data source. Is there a 'conventional' way to add a combobox to a grid (that's connected to a data source)?

[programmerdelphi2k 237]

FMX sample: using more easy way to "use a list of values in a column" = PopUpColumn on StringGrid

 

type
  TForm1 = class(TForm)
    StringGrid1: TStringGrid;
    PopupColumn1: TPopupColumn;
    Memo1: TMemo;
    procedure StringGrid1CreateCustomEditor(Sender: TObject; const Column: TColumn; var Control: TStyledControl);
    procedure StringGrid1EditingDone(Sender: TObject; const ACol, ARow: Integer);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.fmx}

procedure TForm1.StringGrid1CreateCustomEditor(Sender: TObject; const Column: TColumn; var Control: TStyledControl);
begin
  Memo1.Lines.Add(TimeToStr(now) + ' - CreateCustomEditor');
  //
  // loading values... or anyother sources!
  PopupColumn1.Items.DelimitedText := 'Item1,Item2,Item3';
end;

procedure TForm1.StringGrid1EditingDone(Sender: TObject; const ACol, ARow: Integer);
begin
  Memo1.Lines.Add(TimeToStr(now) + ' - EditingDone');
end;

 

[programmerdelphi2k 237]

other way is using the "var Control" param on "CreateCustomEditor" event:

implementation

{$R *.fmx}

function fncMyComboBox: TComboBox; // my Control used in my TGrid-CustomEditor...
begin
  // it will be "created"... and "destroyed by Grid"
  result := TComboBox.Create(nil);
  //
  result.Items.AddStrings(['One', 'Two', 'Three']);
  //
  result.OnChange := Form1.MyComboBoxChange;
end;

procedure TForm1.MyComboBoxChange(Sender: TObject);
begin
  if not(Sender is TComboBox) then
    exit;
  //
  try
    BindSourceDB1.DataSet.Edit;
    BindSourceDB1.DataSet.FieldByName('MyId').Value := TComboBox(Sender).Selected.Index;
    BindSourceDB1.DataSet.Post;
  except
    // ???
  end;
end;

procedure TForm1.Grid1CreateCustomEditor(Sender: TObject; const Column: TColumn; var Control: TStyledControl);
begin
  if (Column.Index = 0) then
    Control := fncMyComboBox; // who's the "destroyer" now?
end;

initialization

ReportMemoryLeaksOnShutdown := true; // any memory leaks?

end.

    

Edited March 13, 2023 by programmerdelphi2k