On Tue, 21 Jul 2009, Graeme Geldenhuys wrote:
Hi,
I working on a Firebird database that has a default Charset = UTF8. I'm using
the SqlDB package via tiOPF to save and read my data from the database.
I have a table with a field defined as Char(2) and I have set it with a value
"en" which represents a Country Code.
When I read back that value, by TCountry unit tests fail with the following
message.
==========================
1) textrunner.SQL Database tests.TTestCountry.TestCountry_ReadList:
ETestFailure
at $0807F9B4
"Check #1: Failed on ID
Expected:
"en"
But was:
"en "
==========================
Further investigation revealed that when I read back a Char(2) field via
TField.AsString the resulting string is 8 bytes wide. I can see where this
value comes from - Firebird obviously uses 4 bytes per UTF-8 character,
because that is the largest amount of bytes a UTF-8 character can use. Not
very efficient, but that is what Firebird 2.1 does when the Charset = UTF8.
Now I was wondering how to resolve this.
1) Switch all my Char() fields to VarChar() which resolves the problem.
2) Trim(lField.AsString) before I store it in each TCountry.Code property.
3) SqlDB does the TField.AsString trimming for any Char() fields.
Is option #3 viable? This will resolve any similar issue to all future
developers using Firebird with Char() type fields and Charset=UTF8.
You may never trim these fields;
The database contains always the declared number of characters: the value
is trimmed with a space till the number of declared characters is reached.
TField.AsString returns what is in the database, which seems to be 8 characters
in your case.
Or should I opt for options #1 or #2 instead. Option #1 is probably the least
amount of effort because the project I am working on is new, so there is no
existing database that need to be converted. Problem being that another
developer down the line might add a new field of type Char() and then we sit
with the same problem again.
What is your thoughts on this. As far as I know MSEgui does automatic
trimming of spaces in the TField, so should this maybe be done in SqlDB
(Interbase/Firebird) as well?
No, because it is fundamentally wrong.
The question should be:
Why does Firebird report 8 characters to your application ?
Michael.
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