Daniele Forghieri wrote:
> Il 28/03/2014 10:16, Peter Otten ha scritto:
>> Daniele Forghieri wrote:
>>
>>> Hi to all. I'm using sqlite3 with python 2.7 on windows.
>>>
>>> I use the query substitution parameters in my query but I need to pass
>>> part of the query to a function, something like (it's not the real
>>> examples, just to clarify the question):
>>>
>>> def loadAll(cursor, id, queryAdd = None):
>>> if queryAdd is None:
>>> qry = 'select * from files where catalog = ?'
>>> else:
>>> qry = 'select * from files where catalog = ? and %s' %
>>> (queryAdd))
>>>
>>> cursor.execute(qry, (id, ))
>>> ...
>>>
>>> I would like to use the query substitution even when I create, in
>>> another piece of code, the queryAdd part, something like:
>>>
>>> queryAdd = cursor.querySubst('enabled = ? and hide = ? and data > ?',
>>> (enabled, hidden, min_date, ))
>>>
>>> when the function take care of the date format, quoting the parameter
>>> and so on
>>>
>>> It's possible or not ?
>> You can use named parameters
>>
>> http://docs.python.org/dev/library/sqlite3.html#cursor-objects
>>
>> Your function might become (untested)
>>
>> def load_all(cursor, parameters, condition="catalog = :id"):
>> query = 'select * from files where ' + condition
>> cursor.execute(query, parameters)
>> ...
>>
>> load_all(
>> cursor, dict(id=42, fromdate=datetime.date.today()),
>> condition="catalog = :id and date >= :fromdate")
>>
>
> Thank. With this I can solve the problem but I have to specify the
> query twice and if I have to change something I need to made it
> everywhere I use the function and is something I would like to avoid.
How about that one:
def query_subst(sql, parameters):
return sql, parameters
def load_all(cursor, id, query_add=None):
query = 'select * from files where catalog = ?'
parameters = (id,)
if query_add is not None:
query += " and " + query_add[0]
parameters += query_add[1]
cursor.execute(query, parameters)
...
enabled = True
hidden = False
min_date = datetime.date.today()
query_add = query_subst(
'enabled = ? and hide = ? and date > ?',
(enabled, hidden, min_date))
load_all(cs, 42, query_add)
> I also don't like very mush to pass or create a dict for a function
> call but that's probably me coming from old plain C ;)
Get over it ;)
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