DB-API corner case (psycopg2)

M.-A. Lemburg mal at egenix.com
Fri Aug 1 21:04:28 CEST 2008


On 2008-08-01 20:38, Thomas Guettler wrote:
> I forgot to mention where I stumbled about this.
> 
> Django has a wrapper:
> http://code.djangoproject.com/browser/django/trunk/django/db/backends/util.py
> 
>  	    def execute(self, sql, params=()):
>  	        start = time()
>  	        try:
>  	            return self.cursor.execute(sql, params)
>  	        finally:
> 
> Most people don't have a percent sign in the variable sql.
> 
> I guess
>     cursor.execute(sql, None)
> is not portable for all database backends.
> 
> I guess this should be the best solution:
> if params:
>     return self.cursor.execute(sql, params)
> else:
>     return self.cursor.execute(sql)
> 
> What do you think?

Not good enough... you should use this:

   	    def execute(self, sql, params=None):
   	        start = time()
   	        try:
                     if params is None:
  	                return self.cursor.execute(sql)
                     else:
   	                return self.cursor.execute(sql, params)
   	        finally:
                     ...

>   Thomas
> 
> Thomas Guettler schrieb:
>> Hi,
>>
>> I discovered this:
>>
>> import psycopg2
>> connection=psycopg2.connect("dbname='...' user='...'")
>> cursor=connection.cursor()
>> cursor.execute('''SELECT '%' ''') # Does not fail
>> cursor.execute('''SELECT '%' ''', ()) # Does fail
>>
>> Traceback (most recent call last):
>>   File "/localhome/modw/tmp/t.py", line 5, in <module>
>>     cursor.execute('''SELECT '%' ''', ()) # Does fail
>> IndexError: tuple index out of range
>>
>> Is this a bug in psycopg2?
>>
>> How do other PEP 249 implementation behave?
>>
>>  Regards,
>>    Thomas
>>
> --
> http://mail.python.org/mailman/listinfo/python-list

-- 
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