Datetime issues
lazarus / 16-Databases

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mangakissa · 2014-03-18 21:31

Filling a TDBEdit as DateTimefield (example 40-40-2000) occurs an
error. The application give a dialog where you can choose OK to go
further and Cancel to close the application.

Why is it a risk to go further?
Why closes my application completely when I choose CANCEL?
Who is giving this Dialog?
How can I run my application normal without this dialog?

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taazz · 2014-03-18 21:52

Quote from: mangakissa on March 18, 2014, 10:31:47 pmFilling a TDBEdit
as DateTimefield (example 40-40-2000) occurs an error. The application
give a dialog where you can choose OK to go further and Cancel to
close the application.

Why is it a risk to go further?
it is not a risk, its just the defalt exception dialog a lot of
problems with this but hey you can change it as far as I know.
Quote from: mangakissa on March 18, 2014, 10:31:47 pmWhy closes my
application completely when I choose CANCEL?
well the message says it all press cancel to kill the application aka
exit when pressing cancel so as expected.
Quote from: mangakissa on March 18, 2014, 10:31:47 pmWho is giving
this Dialog?
Default dialog comes with LCL.
Quote from: mangakissa on March 18, 2014, 10:31:47 pmHow can I run my
application normal without this dialog?
add a appliction.onexception handler and show your own message or
simple ignore it. Not a good practise in my book but the only work
around I know.

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marcov · 2014-03-19 13:17

I think it is simply bad programming.  A droppable component should
never generate exceptions like econverterror.

Please file a bug. (and test the/a similar case with delphi if you
can)

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mangakissa · 2014-03-19 21:24

Delphi also creates a  econverterror., but doesn't crash.
Create a small Delphi application (TClientdataset) and a small Lazarus
application (TBufdataset).
Delphi does continue.

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mangakissa · 2014-03-20 08:07

Also reported in bugtracker

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wp · 2014-03-21 13:34

In my own applications I usually try to avoid exceptions. Therefore,
if there is an input control I check the input data before passing
them to other structures.

In your demo application, I originally thought it would be sufficient
to catch the incorrect input in the BeforePost event of the dataset.
But since you are using a DBEdit the error happens way before posting
when the edit converts the string to a field value. Luckily there is
another event to catch the error: Use the OnGetText event of the field
linked to the DBEdit. This is called when the field of the Dataset
"gets" the string from the connected data-sensitive control and
converts it to the data type needed. In case of an error, call "Abort"
to raise a silent exception.

Code: [Select]procedure TForm1.BufDataset1birthday1SetText(Sender:
TField; const aText: string
  );
var
  d: TDate;
begin
  if (AText = '') then begin
    MessageDlg('Input required for birthday', mtError, [mbOK], 0);
    Abort;
  end;
  if not TryStrToDate(AText, d) then begin
    MessageDlg(Format('"%s" is not a valid date.', [AText]), mtError,
[mbOk], 0);
    Abort;
  end;
end;

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mangakissa · 2014-03-21 15:32

Thanks. I shall look at your workaround. But it's still a real bug.