TStringField keeps only half of the typed data
lazarus / 16-Databases

----------------------------------------------------------------------
atasoft · 2014-08-23 14:39

Hi,
I am using Zeos 7.1.3 stable in Lazarus 1.0.14 and I have the
following problem:
In a TZQuery I use a persistent TSringField and I set its Size and
DisplayWidth to 20. I have a DBEdit in a Lazarus form connected to the
TStringField.

When I run the compiled program and I write English letters the DBEdit
allows me correctly to write 20 characters.
If I write Greek (or other Unicode) characters, it allows me to write
20 characters but it keeps only the first 10 characters.
These is very annoying for the users.

Notice that the TZConnection component has these settings
ClientCodePage=UTF8 and ControlsCodePage=cCP_UTF8. The database is
SQLite3.

I will appreciate any help which will solve the above problem.

Best regards,
Andreas

----------------------------------------------------------------------
howardpc · 2014-08-23 17:00

Add
Code: [Select]uses LazUTF8;
to your unit, and set Size to UTF8Length(YourLongestUTF8string) rather
than to a count of (apparent) ansi characters.

----------------------------------------------------------------------
atasoft · 2014-08-24 09:19

Quoteset Size to UTF8Length(YourLongestUTF8string) rather than to a
count of (apparent) ansi characters.
Ok but this will not solve the problem. I can add double the size of
maximum string. The Zeos 7.1.3 persistent TSringField sets the size
equal to 4x the varchar size of database.

This gives enough size but the problem still exists if the user uses
the field to write for example names both in Greek (or any unicode
language) and English. He wants to be able to write for example ONLY
20 characters independently of the language (English or Greek).

Is there a way to limit the size of persistent field in the number of
characters and not number of bytes?
One way is to use the property "MaxLength" of the DBComponents. Any
other solution?

I am using the database SQLite and its varchar size is not limited by
the database. Therefore if the persistent TSringField size calculates
number of characters and not bytes would be OK. It would be fine if
there was option to choose how the size will be internally calculated
(in bytes or characters).

----------------------------------------------------------------------
EgonHugeist · 2014-08-24 09:57

Changing DisplayWidth of the Fields seems to work with persitent
fields only.

Did commit a patch. See https://sourceforge.net/p/zeoslib/tickets/58/

----------------------------------------------------------------------
atasoft · 2014-08-25 19:26

I downloaded ZEOSLIB subversion R3280. I installed it on Lazarus 64bit
(windows). I could not check it because while the TZConnection works
OK as soon as I open any ZQuery I get error "Access Violation". I will
try it on Lazarus 32bit.