Hello,

I'm trying to save an empty string in a TMemoField, but it always saves a double quote ('') instead.

Attached a small example to reproduce the error.

My environment:

PostgreSQL 8.4;
Lazarus 1.0.10 r41613 FPC 2.6.2 i386-win32-win32/win64 (Windows 8 - 64bit);

Thank you!

silvioprog wrote

I'm trying to save an empty string in a TMemoField, but it always saves a double quote ('') instead. Attached a small example to reproduce the error.

It seems you're trying to clear the field (which IMO should give NULL). Shouldn't you use .AsString to assign an empty string value to it?

Hi Silvio,
I cann't reproduce your error in 2.7.1 (trunk)
Fix in rev.25411 closes also problem you mentioned. (but before this rev. problem existed)
But now I get another error, which says that there is "no insert query specified" because all fields in posted row are empty (null) (which is okay from point of application view, but this situation is not handled when ApplyingUpdates)
-Laco.

2013/9/10 Reinier Olislagers

Even passing AsString = '' it saves a double quote in database.

2013/9/10 LacaK

Is there any place where I can download a FPC stable with this fix? I don't feel comfortable using a unstable FPC to compile a project to use in production.

There is no stable, because there is currently no release of 2.8 planned. Maybe it will merged to 2.6.3 then you could get it once 2.6.4 is released.

You should nevertheless test using a development version snapshot whether this fix does indeed fix your problem though.

Regards,
Sven

2013/9/10 Sven Barth

Hm... Now I really don't know what to do. :/

I downloaded a snapshot now. I'll test it and send the result here ...

2013/9/10 silvioprog

Same problem in FPC 2.7.1 (my environment: Lazarus 1.1 r42538 FPC 2.7.1 i386-win32-win32/win64).

The pgAdmin screenshot:

http://imagebin.org/270446

So it seems to be a different problem anyway...

Regards,
Sven

silvioprog wrote / napísal(a):

Strange ;-)
Can you please attach and send your bufdataset.pas ? -Laco.

silvioprog wrote / napísal(a):

Now doing more tests. I see, that in pgAdmin when I use right click on table and use "View Data" then '' (two single quotes) are shown in TEXT column, but when I use SQL and type:
select * from <table name> then empty fields are shown ... so it seems to me, that bug is in pgAdmin, does not ?
-Laco.

2013/9/11 LacaK

Yes:

http://pastebin.com/nqVnXAs5

2013/9/11 LacaK

The bug is in FCL. Please see the steps in my comparison:

1. first I inserted a record via pgAdmin: insert into test (id, fieldtext)
values (1, null);
2. after, I executed this demo: http://pastebin.com/HS8DZkDV;
3. finally, I made this selection in pgAdmin:
  select * from test
  where fieldtext is null;

And the result is:

id | fieldtext
-----------------
1 |

But, when I select so:

select * from test
where fieldtext = ''

The result is:

id | fieldtext
-----------------
2 |

Then SQLdb is saving an empty string instead of null. :o

I tried it:

q.FieldByName('fieldtext').Value := Null;

Instead of:

q.FieldByName('fieldtext').Clear;

Same result, it is saving an empty string instead of null.

silvioprog wrote / napísal(a):

This is not latest version. Correct version is here: http://svn.freepascal.org/cgi-bin/viewvc.cgi/trunk/packages/fcl-db/src/base/bufdataset.pas?view=log

L.

silvioprog wrote / napísal(a):

Try in pgAdmin do:
insert into test (id, fieldtext) values (1, '');
Then use "View Data" and you will see two single quotes instead of empty cell.

Yes it is true for your version of bufdataset.pas, but it is fixed in trunk.

L.

2013/9/11 LacaK

I'm searching a FTP with an update FPC to test it again. I'm using it:

ftp://freepascal.dfmk.hu/pub/lazarus/snapshots

But the latest FPC in this FTP is of 2013-09-01.

2013/9/11 silvioprog

Tested on Linux and worked fine.

Thank you very much friends! (y)

LacaK wrote

Now doing more tests. I see, that in pgAdmin when I use right click ontable and use "View Data" then '' (two single quotes) are shown in TEXTcolumn, but when I use SQL and type: select * from <table name> then empty fields are shown ... so itseems to me, that bug is in pgAdmin, does not ?

maybe not a bug... i regularly display strings with quotes around them... especially if they are empty... that way i can actually see that they are empty...

2013/9/11

Seems better if pgAdmin use <EMPTY> instead of '', because the user can use double quote.