ODBC/TSQLQuery:TWideStringField.AsString returns '???'

[tk]

Hi,
I'm testing a connection to my MSSQL database via Lazarus TODBCConnection/TSQLQuery/TSQLTransaction. I cannot display my nvarchar columns properly. For example in my TDBEdit I get '???' for these columns and any record. I discovered the problem is located at TWideStringField.AsString which returns '???' instead of valid text. The same result I get for TWideStringField.AsWideString.

Has anybody similar experience?

Thx

[Zoran]

Try using UTFEncode function.
Perhaps putting the Field's OnGetText event would be the best for you. Something like this:

procedure TForm1.SQLQuery1Field1GetText(Sender: TField;
  var aText: string; DisplayText: Boolean);
begin
  aText := UTF8Encode(Sender.AsString);
end;

After that you can use Field1.AsString normally.

[tk]

I tried now and didn't get expected results. It seems to be a FPC problem. The dataset (or something else) assigns a TWideStringField for a table field that is natively not UTF16. I tried the following code and got expected text in S for this case:

Code: [Select]

var
  S: string;
...
SetLength(S, AField.DataSize);
AField.GetData(@S[1], True);
...

Of course I cannot use this because in other cases where fields are natively in UTF16 format this would not work. Perhaps I should place new issue in FPC bugtracker later.

[Zoran]

Did you look in the LConvEncoding unit? Apart from functions for converting particular character sets, in that unit you can also find the function named GuessEncoding. I haven't tried this function, maybe it can help you determine whether the string you got from database is UTF16 or not, and if not, which encoding it is.

I don't know... I hope that someone better experienced in this than me will have to say something to help you.

[calvarez]

I'm trying to connect to a MSSQL server from Linux. You could connect mssql from linux?

Thanks for your time.