more Memo field UTF8 adventures

[pwatel]

As everything these days are unicode
New Delphi, WEB pages, windows, Firebird (UTF8) and memo fields
It is kind of natural that you could use a database blob aka memo to store
for example a web page full of unicode...

Yet why is it such a headache that one cannot do simply with your product
the following

Database and field being UTF8
SELECT from WHERE etc

Open the query and
Q.fields[0].asstring showing the right stuff
how involved it has to be????
I have spent 2 days dicking around to try to get the stuff to work
and if I cut and paste the content of the memo to a file or to an editor it work...
Please any ideas ???

by the way it should be as simple to do on a update or insert a block of text

thanks regards
Philippe Watel

[Plash]

You should set the EnableMemos and UseUnicode options of TIBCConnection to True. In this case UTF8 BLOBs are automatically decoded by IBDAC.

[pwatel]

Thaks for your answer
It works on the select now
but how about on Update or insert
what is the correct synax

q.sql := 'update
Set memofield = :memofield';
q.ParamByName(memofield).Value := bigstring;
q.execute
or you have to add
q.ParamByName(memofield).DataType := ftblob;
q.ParamByName(memofield).AsIbBlob.IsUnicode := Self.UseUnicode;
The documentation or help is a bit non existant (or at least could not find examples)
regards
PW

[Plash]

You should set DataType of the parameter to ftWideMemo:

Code: Select all

q.ParamByName(memofield).DataType := ftWideMemo; 
q.ParamByName(memofield).Value := bigstring; 
q.Execute;

In this case IBDAC encodes parameter's value to UTF8 before it sends the value to the server.

You can also set the UnicodeMemoParameters global variable from the IBC unit to True. In this case values of ftMemo parameters will be also encoded to UTF8:

Code: Select all

q.ParamByName(memofield).AsMemo := bigstring; 
q.Execute;

[mischerr]

Hello.

This works fine, but on the BDE it was possible to set a parameter to NULL.

Code: Select all

    if Text = '' then begin
      Param.Clear;
      Param.DataType := ftMemo;
    end else
      Param.AsMemo := Text;

Param is TParam - the result of ParamByName().

When I do this with IBDAC, I get an AV when I execute my SQL statement.

What is the suggested way to set a parameter for Blob / Memo to NULL?

Rgds,
Michael

[Plash]

In IBDAC you cannot change value of BLOB parameter using the TParam class. You should use TIBCParam or TDAParam.

[mischerr]

Well, the param is the result of ParamByName() called on an TIBCQuery.
So it is a TIBCParam. It's only passed to my function as TParam like this:

Code: Select all

procedure SetMemoParam (const Param : TParam; const Text : string);
begin
  if Assigned(Param) then begin
    if Text = '' then begin
      Param.Clear;
      Param.DataType := ftMemo;
    end else
      Param.AsMemo := Text;
  end;
end;

As TIBCParam inherites from TParam this shoud be possible.

So, how is it possible to set a blob parameter to NULL with a TIBCParam without changing the SQL statement?

[Plash]

TDAParam has its own code for setting the parameter value. Methods in TParam are not virtual. So the code in TDAParam is not executed if you access the parameter using the TParam variable.