SqlDB, OnGetText, SIGSEGV
lazarus / 16-Databases

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tintinux · 2011-04-11 09:13

Hi

I connect to a MS-Access "database" with Lazarus 0.9.30/Windows,
SqlDb,  TODBCConnection and TSqlTransaction.

If I assign OnGetText event in a TSqlQuery Field, I get at runtime a
SIGSEGV when the event handler is called.

Even if nothing, or a mere constant assignment, is in the event
handler. I was not able to find the error using the debugger.

I have been using succesfully OnGetText with ZeosLib components, but I
never used before SqlDB components.

Anyone knows what could be the reason ?  Was successful in this area ?

Regards
Tintinux

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Lacak2 · 2011-04-12 05:36

Can you post here some test program, example, how-to reproduce problem
?

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tintinux · 2011-04-12 08:11

Hi

Thanks for your help.

I have attached a sample program.

You must provide a MS-ACCESS database named test.mdb
There is a button on the form to delete, create and populate a table
named test

When the OnGetText event is attached to the field Name, to display
uppercase in this example, I get the SIGSEGV error.

If you have any issue or can't reproduce, just tell !

Regards
Tintinux

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Lacak2 · 2011-04-12 09:56

Try this:
put into unit UnitMenu after
{$mode objfpc}
this:
{$H+}

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tintinux · 2011-04-12 11:41

Hi,

Many thanks, it works fine with {$H+}

Don't you think this could be avoided by some change in a next release
?
In this case, a bug report should be created. Do you want to do it, or
me ?

Regards

Tintinux

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Lacak2 · 2011-04-12 12:33

I am not sure if it is a bug , but I agree, that it leads to very
wrong results.

Problem is in fact, that without {$H+} is string equal to shortstring
and with {$H+} is string equal to ansistring type.

AV can be avoided also without adding {$H+}, but you must change
definition of method:
    procedure SQLQuery1nameGetText(Sender: TField; var aText:
ansistring;
      DisplayText: Boolean); 

So you can report it as bug, but I am afraid, that it will be closed
with "Won't fix"   ... but you can at least try

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marcov · 2011-04-12 13:48

I'd say file a bug, and name this as a reason why "use ansistrings"
should be on by default in the "new unit" menu.

The problem is that properties are not typed. If you would do this in
code, you'd get a compilation failure.