TDBNavigator
lazarus / 16-Databases

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ilniko · 2006-03-24 19:37

Hi all,
sorry my ignorance, but I don't know how to stop the execution of a
Button Action in a TDBNavigator.
I've tried calling the ExecuteCancelAction in the BeforeAction event,
but nothing to do.

Nik

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matthijs · 2006-03-25 10:02

What do you want to cancel?
Actions on the database you should cancel in events of the dataset. So
if you are using a TSQLQuery and you want to cancel the posting of
data you should do the cancellation in the BeforePost event.

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ilniko · 2006-03-25 10:19

I use a TDbf.
So I have to call the ExecuteCancelAction in the BeforePost event of
the TDbf, to cancel the post? Or whatelse I have to call to do it?

Nik

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matthijs · 2006-03-25 11:50

No, you just call DataSet.Cancel

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ilniko · 2006-03-25 12:34

I've tried your suggest, but it doesn't work. The dataset try however
to post data in the dbf.
Here's my code:
Code: [Select]
procedure TFMain.DbfPrevBeforePost(DataSet: TDataSet);
begin
  if DbfPrev.FieldByName('pdata').AsString = '' then
    DataSet.Cancel;
end;


Posting data with the "pdata" field blank, cause a Key Violation on
the table index, and even if the DataSet.Cancel is executed, the error
message is shown anyway, so i suppose that the Cancel did not work.

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matthijs · 2006-03-25 14:20

What if you change code to:
Code: [Select]
procedure TFMain.DbfPrevBeforePost(DataSet: TDataSet);
begin
  if DbfPrev.FieldByName('pdata').AsString = '' then
    DbfPrev.Cancel;
end;

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ilniko · 2006-03-25 14:35

I've just tried with DbfPrev.Cancel before of DataSet.Cancel and I
obtained the same result: the dataset post data anyway.
Maybe there is a problem in the DBNavigator?

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matthijs · 2006-03-25 16:24

No, the DB Navigator got nothing to do with this. All the Navigator
does is calling methods from the dataset it is connected to.
Is the BeforePost called at all? You could test this by showing a
message or something like that.

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ilniko · 2006-03-26 11:33

Yes, I called the BeforePost. Not sure if the Cancel procedure was
called, the first thing I do was be put a ShowMessage, and the dialog
appear correctly.
Maybe then the problem is in the TDbf component, that not process
correctly the Cancel procedure.

I'm thinking to do a Frame with the buttons Add, Delete, etc, and do
from myself the code for Insert, Delete, Post, Cancel, etc.