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delphidbgrid

DBGrid: how to prevent a row from being selected?

I have a grid of entries the user will click on to multi-select for a process. Some of the entries will be invalid based upon values of the first selected row.

I know about DBGrid.SelectedRows.CurrentRowSelected, but I cannot find a suitable place for checking my conditions to set it to True or False.

Something like this:

var
  bm: TBookmark;
  CachedIdentity: String;
  CanSelect: Boolean;
begin
  with dgbSkypeConversations do
  begin
    if SelectedRows.Count > 0 then
    begin
      DataSource.DataSet.DisableControls;
      bm := DataSource.DataSet.GetBookmark;
      CachedIdentity := DataSource.DataSet.FieldByName('identity').AsString;
      DataSource.DataSet.GotoBookmark(SelectedRows[0]);
      CanSelect := DataSource.DataSet.FieldByName('identity').AsString <> CachedIdentity;
      DataSource.DataSet.GotoBookmark(bm);
      DataSource.DataSet.FreeBookmark(bm);
      SelectedRows.CurrentRowSelected := CanSelect; 
      DataSource.DataSet.EnableControls;
    end;
  end
end;

I have tried the OnMouseDown events in Application.OnMessage and of the DBGrid and the Form, but they do not work, and there is no TBookmarkList.BeforeInsertItem event. What can I do or must I change?

Solution

  • I would not make it so complicated.
    If the comparison always takes place on the first selection.
    The code I use here has hardcoded Value.
    No jump around to bookmarks.

    // first selection----------------------------- 
if DBGrid1.SelectedRows.Count = 1 then begin
   CachedIdentity := 'Sonnenbrille'; // Sunglasses
 //CachedIdentity := DataSource.DataSet.FieldByName('identity').AsString;
   Exit;
end;

    Do the comparison

    if DBGrid1.SelectedRows.CurrentRowSelected then begin
 //if CachedIdentity <> DataSource.DataSet.FieldByName('identity').AsString
   if Pos(LookingFor,DBGrid1.DataSource.DataSet.FieldByName('haupttxt').AsString)=0
   then  DBGrid1.SelectedRows.CurrentRowSelected := False;
   ShowMessage(IntToStr(DBGrid1.SelectedRows.Count));
end;

    We can see two are selected so
    ShowMessage(IntToStr(DBGrid1.SelectedRows.Count));

    shows 2

    enter image description here

    Now we want to select the line

    SPORTLICH, ELEGANTE GUCCI SONNENBRILLE

    We know a simple Pos() Sonnenbrille to find SONNENBRILLE Pos() will be = 0, so a selection-will not take place.

    enter image description here

    ShowMessage(IntToStr(DBGrid1.SelectedRows.Count));

    shows 2 too

    CODE:

    var
CachedIdentity : string;

procedure TForm2.canSelectedV1;
begin
    // first selection----------------------------- 
if DBGrid1.SelectedRows.Count = 1 then begin
   CachedIdentity := 'Sonnenbrille'; // Sunglasses
 //CachedIdentity := DataSource.DataSet.FieldByName('identity').AsString;
   Exit;
end;
if DBGrid1.SelectedRows.CurrentRowSelected then
 begin
 //if CachedIdentity <> DataSource.DataSet.FieldByName('identity').AsString
   if Pos(LookingFor,DBGrid1.DataSource.DataSet.FieldByName('haupttxt').AsString)=0
   then  DBGrid1.SelectedRows.CurrentRowSelected := False;
   ShowMessage(IntToStr(DBGrid1.SelectedRows.Count));
 end;
end;

procedure TForm2.DBGrid1MouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
canSelectedV1;
end;

procedure TForm2.DBGrid1KeyUp(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
canSelectedV1;
end;

end.