Обсуждение: empty string in composite data types

Hi,

I noticed some (imho) odd behaviour while using composite data types.
Empty strings will be returned as None instead of '' in Python.

For example:

sql> CREATE TYPE testtype AS (id INT, label TEXT);

python> import psycopg2
python> import psycopg2.extras
python> db = psycopg2.connect(...)
python> caster = psycopg2.extras.register_composite('testtype', db)
python> cursor = db.cursor()
python> cursor.execute("SELECT (1, '')::testtype")
python> cursor.fetchone()[0]
testtype(id=1, label=None)

Is this behaviour intended? Or is there some flag I don't know about (I
have found none) that gives me empty strings instead?

Any help would be appreciated.


Cheers,
  Chris

On Mon, Dec 3, 2012 at 12:15 PM, Christian von Kietzell
<christian@vonkietzell.de> wrote:
> Hi,
>
> I noticed some (imho) odd behaviour while using composite data types.
> Empty strings will be returned as None instead of '' in Python.
>
> For example:
>
> sql> CREATE TYPE testtype AS (id INT, label TEXT);
>
> python> import psycopg2
> python> import psycopg2.extras
> python> db = psycopg2.connect(...)
> python> caster = psycopg2.extras.register_composite('testtype', db)
> python> cursor = db.cursor()
> python> cursor.execute("SELECT (1, '')::testtype")
> python> cursor.fetchone()[0]
> testtype(id=1, label=None)
>
> Is this behaviour intended? Or is there some flag I don't know about (I
> have found none) that gives me empty strings instead?

No, I'm afraid it's a bug. Could you please open a ticket in the
tracker? I'll take a look at it this evening.

-- Daniele

On Mon, Dec 3, 2012 at 12:49 PM, Daniele Varrazzo
<daniele.varrazzo@gmail.com> wrote:
> On Mon, Dec 3, 2012 at 12:15 PM, Christian von Kietzell
> <christian@vonkietzell.de> wrote:
>> Hi,
>>
>> I noticed some (imho) odd behaviour while using composite data types.
>> Empty strings will be returned as None instead of '' in Python.
>>
>> For example:
>>
>> sql> CREATE TYPE testtype AS (id INT, label TEXT);
>>
>> python> import psycopg2
>> python> import psycopg2.extras
>> python> db = psycopg2.connect(...)
>> python> caster = psycopg2.extras.register_composite('testtype', db)
>> python> cursor = db.cursor()
>> python> cursor.execute("SELECT (1, '')::testtype")
>> python> cursor.fetchone()[0]
>> testtype(id=1, label=None)
>>
>> Is this behaviour intended? Or is there some flag I don't know about (I
>> have found none) that gives me empty strings instead?
>
> No, I'm afraid it's a bug. Could you please open a ticket in the
> tracker? I'll take a look at it this evening.

Thank you for the report. Sorry for the stupid bug
(https://github.com/dvarrazzo/psycopg/commit/9a031db8b90488afb59e0d6c8995398c88b6bc41).

To be released in 2.4.6 (which is really due now).

-- Daniele

On Mon, 2012-12-03 at 14:30 +0000, Daniele Varrazzo wrote:
> =Thank you for the report. Sorry for the stupid bug
> (https://github.com/dvarrazzo/psycopg/commit/9a031db8b90488afb59e0d6c8995398c88b6bc41).
>
> To be released in 2.4.6 (which is really due now).

Thanks a lot for fixing it so quickly. That's why I love Free
Software :)


  Chris