Checking Date Format in StringGrid

[Badger]

Hi All

I'm trying to trap incorrect date input in a string grid by checking the previous cell when OnSelectCell is called.

Getting it to trap the error is easy but I want it to return focus to the cell with the error.  The following code traps the error but the new cell still gets focus.

Any (helpful) suggestions?

Code: Pascal  [Select][+][-]

1. procedure TIncomeExpenditureForm.IncomeSelectCell(Sender: TObject; aCol,
2.   aRow: Integer; var CanSelect: Boolean);
3. var
4.   dummydate:TDate;
5. begin
6.   //Check for proper Date format
7.   if (PreviousCell.x=0) and (Income.Cells[PreviousCell.x,PreviousCell.y] <>'') then
8.   begin
9.     try
10.       dummydate:=StrToDate(Income.Cells[PreviousCell.x,PreviousCell.y]);
11.     Except
12.       ShowMessage('Date Format is incorrect');
13.       //move focus back to previous cell
14.       Income.Col:=PreviousCell.x;
15.       Income.Row:=PreviousCell.y;
16.     end;
17.   end;
18.  
19.   //Remember New Cell Position
20.   PreviousCell.x:=aCol;
21.   PreviousCell.y:=aRow;
22.  
23. end;        

             

[jamie]

are you sure the Exception is getting raised ?

 So you see the MessageBox ?

Also it could be that the cell is repositioned after the call block..

You may need to take it out of edit mode move it and then put it back into edit mode..

if that does not work then just send a User message to the form via a PostMessage and then process it later when the code has left this block...

  But I would try to take it out of edit mode first before moving it then put it back into edit mode.

[bytebites]

Code: Pascal  [Select][+][-]

1. procedure TIncomeExpenditureForm.IncomeValidateEntry(sender: TObject; aCol, aRow: Integer;
2.   const OldValue: string; var NewValue: String);
3. var
4.   dummydate: TDateTime;
5. begin
6.   if (aRow=0) and not TryStrToDate(Income.Cells[aCol,aRow],dummydate) then NewValue:=OldValue
7. end;
8.  

[Badger]

are you sure the Exception is getting raised ?

 So you see the MessageBox ?

Yes  the message box appears.  It's just that for some reason (or perhaps a very good reason) the program seems to ignore the setting of Row and Col and just moves focus to the cell originally clicked in stead of focusing on the previous cell.

procedure TIncomeExpenditureForm.IncomeValidateEntry(sender: TObject; aCol, aRow: Integer;
  const OldValue: string; var NewValue: String);

I don't  think that will help, I want the program to return to the previous cell so the user can correct it.

jamie's other suggestions are beyond my limited abilities

[howardpc]

You either need to use bytebytes' solution, or set a cell editor that is a date editor (rather than a string editor) such as TDateEdit, which would prevent user entry of an invalid dates.

Trying to roll your own validation routine and ignoring the built in OnValidateEntry event will almost certainly lead to grief.
OnSelectCell is a poor choice, since it is called so frequently, and in a large grid code such as you show, even if it worked, would slow the UI.
TStringGrid has been designed with an underlying, largely hidden, internal messaging system. Without understanding that you are unlikely to get a single-threaded LCL UI to respond in the way you hope it will by interrupting the grid cell selection mechanism.