Lazarus

Programming => Databases => Topic started by: lainz on July 05, 2022, 12:11:44 am

Title: [SOLVED] DBGrid Class: EDatabaseError Mensaje: "1.650,00" is not a valid float
Post by: lainz on July 05, 2022, 12:11:44 am

When I'm editing on a DBGrid and I type a float with a wrong format like this one: "1.650,00" I get an exception like this:

Class: EDatabaseError
Mensaje: "1.650,00" is not a valid float

There's a way to prevent the exception? And give the user a proper error message, like: 'The number you entered has a wrong format, please try again.' or something around the lines.

Thanks.

Title: Re: DBGrid Class: EDatabaseError Mensaje: "1.650,00" is not a valid float
Post by: wp on July 05, 2022, 12:47:44 am

I had thought this would be easier...

DBGrid inherits from its ancestors the event OnValidateEntry, however, it is declared only as protected and thus not accessible by the standard DBGrid. But it can easily be subclassed it to make the event public. Add the following declaration to the top of the form with the DBGrid (or to a separate unit which must be at the end of the uses line!):

Code: Pascal  [Select][+][-]

1. type
2.   TDBGrid = class(DBGrids.TDBGrid)
3.   public
4.     propety OnValidateEntry;
5.   end;

Then write a handler for this event, something like this:

Code: Pascal  [Select][+][-]

1. procedure TForm1.ValidateEntryHandler(Sender: TObject; ACol, ARow: Integer;
2.   const OldValue: string; var NewValue: String);
3. var
4.   x: Double;
5. begin
6.   if (DBGrid1.SelectedField is TFloatField) and not TryStrToFloat(NewValue, x) then
7.   begin
8.     MessageDlg(NewValue + ' is not a valid float.', mtError, [mbOK], 0);
9.     Abort;
10.   end;
11. end;

Assign this handler to the DBGrid before its usage, e.g. in the form's OnCreate event:

Code: Pascal  [Select][+][-]

1. procedure TForm1.FormCreate(Sender: TObject);
2. begin
3.   ...
4.   DBGrid1.OnValidateEntry := @ValidateEntryHandler;
5. end;

Title: Re: DBGrid Class: EDatabaseError Mensaje: "1.650,00" is not a valid float
Post by: korba812 on July 05, 2022, 12:58:02 am

You can validate input text in TField.OnSetText event, and raise an EAbort exception if the value is invalid or just leave contents of field unchanged.

Title: Re: DBGrid Class: EDatabaseError Mensaje: "1.650,00" is not a valid float
Post by: lainz on July 05, 2022, 02:00:19 am

@wp thanks, but unfortunately that code didn't work. I've tested on Lazarus 2.2.2 32 bit on Windows.

@korba812 thanks that worked!

Code: Pascal  [Select][+][-]

1.  
2. ...
3.  
4. sqlqyProductos.Fields.FieldByName('Stock_Fisico').OnSetText:=@OnSetTextStockFisico;
5.  
6. ...
7.  
8.  
9. procedure TfrmInventario.OnSetTextStockFisico(Sender: TField;
10.   const aText: string);
11. var
12.   o: double;
13. begin
14.   if not TryStrToFloat(aText, o) then
15.   begin
16.     MessageDlg(aText + ' NO es un número con un formato correcto.', mtError, [mbOK], 0);
17.     Abort;
18.   end
19.   else
20.   begin
21.     Sender.Value := o;
22.   end;
23. end;

Title: Re: DBGrid Class: EDatabaseError Mensaje: "1.650,00" is not a valid float
Post by: wp on July 05, 2022, 06:42:17 pm

Quote from: lainz on July 05, 2022, 02:00:19 am

@wp thanks, but unfortunately that code didn't work. I've tested on Lazarus 2.2.2 32 bit on Windows.

Strange, I had tested it before posting, and it had worked. But anyway, korba812's solution is much better because input validation should not be performed by the visual controls but by the database itself.