[sqlalchemy] Re: Filter by optional attributes.
use keywordargs as dictionary, i.e.
...query.filter( **kwargs)
where the kwargs are a dict made by u containing only the required
fields. e.g.
kwargs={}
if foo_id: kwargs['fooid']=fooid
...
u can make it more generic (but more dangerous) by passing any kwargs
coming to your func straight down to filter():
def myfunc( self, whateverotherstuff, **filterkwargs):
.. query.filter( **filterkwargs)
or some combination inbetween.
dont forget that filter( ...) does AND of the criterias.
svil
On Tuesday 15 July 2008 14:55:01 Heston James - Cold Beans wrote:
Good morning guys,
I'm looking for a way in which I can query my database for records
which meet multiple, optional arguments. I'm looking to encapsulate
access to this using a service layer, I want to create a method
like this:
def get_foos(self, foo_id=, foo_firstname=,
foo_lastname=):
foos = session.query(Foo).filter_by(foo_id=foo_id,
foo_firstname=foo_firstname, foo_lastname=foo_lastname)
return foos
Now, the thing I'm struggling with is how to make all those
attributes optional. Because at the moment I call that method like
so:
get_foos(foo_id=2)
I get no results returned because SQLAlchemy is looking for records
that not only have an id of 2 but also have a first and last name
which is an empty string.
What I would ideally like to do is only have it filter by the
arguments for getfoos() which are not empty strings. This would
allow me to build a more reusable query method.
Is this possible? And how would one achieve it?
Cheers,
Heston
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[sqlalchemy] Re: Filter by optional attributes.
Hi Svil:
use keywordargs as dictionary, i.e.
...query.filter( **kwargs)
where the kwargs are a dict made by u containing only the required
fields. e.g.
kwargs={}
if foo_id: kwargs['fooid']=fooid
That sounds like a fair enough solution to me, seems safer than the more
generic version.
Thanks for the tip mate, sounds really great. I'll play around with that
concept.
Heston
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[sqlalchemy] Re: Filter by optional attributes.
Hello Again Svil: That sounds like a fair enough solution to me, seems safer than the more generic version. Thanks for the tip mate, sounds really great. I'll play around with that concept. Heston I've tested this little concept and it works really nicely :-D thanks. One quick question I'd like to pick your brain on. With filter(), is that filter applied at the SQL level? Or are _all_ records returned from the database and then SQLAlchemy applies the filter? I'm just trying to get an idea of performance when we have many records, I'd hate to be pulling them _all_ from the database with each query. Heston --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: Filter by optional attributes.
Hi, pass an echo=True to the create_engine() (or whereever else u could pass that) and u'll see the sql. Ok, I see! Perfect! I've just configured logging on this so I can keep track, looks excellent. Heston --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
