Problem - space characters added behind text in DBGrid
lazarus / 16-Databases

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Tom83 · 2010-11-25 08:18

Hi,
I have a Firebird database (using UTF8 encoding). I connect to the
database with TIBConnection component and I set TIBConnection.CharSet
to 'UTF8'. Now I have the following problem with displaying values
from char(n) columns:
In the database I have a column:

code char(3)

I insert a value to this column, e.g. 'ABC'. When I display the value
of this column in FlameRobin, it works correctly, there is 'ABC'. But
when I display the value in DBGrid or other database components, there
is 'ABC         ', so it added 9 spaces behind the text.
The same problem occurs when I assign the value of the column to the
variable:

var A: string;
.
.
.
A:=SQLQuery1.FieldByName('Code').AsString;

In A there isn't 'ABC', but there is 'ABC         '. I know I can
simply delete these unwanted spaces, but is there another solution
(better and more comfortable) how to get rid of these additional
spaces?

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Lacak2 · 2010-11-25 09:32

Can you look at SQLQuery1.FieldByName('Code').DataSize
what value it returns ?

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Tom83 · 2010-11-25 09:43

It returns 13.

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Lacak2 · 2010-11-26 04:58

May be, that 3*4+1=13 (
 3-as character size of column char(3)
 4-as max.count of bytes per character in UTF-8
 1-as null string terminator

char(3) field si mapped to ftFixedChar so trailing blanks are not
removed.
In case of varchar(3) trailing blanks will not present (I hope ;-)).

You can remove these unwanted spaces using TField.OnGetText and there
use trim()

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Tom83 · 2010-11-28 15:36

Thank you, I think it will work, but I need more information .
My idea was to write a procedure:

Code: [Select]procedure TForm1.DeleteSpaces(Sender: TField; var aText:
string; DisplayText: Boolean = true);
begin
  aText:=Trim(Sender.AsString);
end;

Then to assign this procedure as an event handler for all the fields
that are of ftFixedChar DataType:

Code: [Select]for I:=0 to SQLQuery1.FieldCount-1 do
  if SQLQuery1.Fields[I].DataType=ftFixedChar then
    SQLQuery1.Fields[I].OnGetText:=@DeleteSpaces;

But I don't know where to put this code. When the SQLQuery is
inactive, there are no fields, so I can't assing them the OnGetText
event handler. I tried to put the code to SQLQuery.AfterOpen event
handler, but it still doesn't work. Probably because the fields are
already filled with data, so the event OnGetText was already executed.
Or is there something wrong with DeleteSpaces procedure?

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Lacak2 · 2010-11-29 06:36

Your code seems ok, also AfterOpen is right place.
OnGetText is called when component request data for displaying or
editing.
Can you test if procedure DeleteSpaces is realy called ... may be,
when you scroll in DBGrid ?

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Tom83 · 2010-11-30 21:44

OK, now it works, the problem was that the Fields.DataType of char(n)
columns was not ftFixedChar, but ftString.