On Sun, 13 Jul 2008 19:02:03 +0300
[EMAIL PROTECTED] wrote:
> > I assume that it would be possible to do it after the Query is
> > gone, at least in theory, since lazy-loaded attributes are able to
> > trigger eager-loads on attributes of their instances, even after
> > the Query is gone. So in essence I am trying to figure out if it's
> > possible to add the eagerload to an instance after-the-fact.
> i'm trying to understand what exactly u want...
> do u want (for an a.b.c.d chain) to query on a (with b being lazy),
> then _later_ tell b.c.d to be eagerloaded and then lazyload b?
> i.e. some sort of options-of-relation-loading like those
> of-query-loading? taking a relation closer to a query in a way?
> like a temporary/dynamic version of current mapper/relation-options
> of sorts.
Yeah, exactly. IOW, I would like to get the exact same behavior as doing
this:
a = sess.query(A).options(eagerload('c')).first()
foo = a.b # triggers eagerload of c
A handful of the codepaths where I'm querying for the objects are
generic functions that service queries for many different classes for
other parts of the app; the gist of all of them is this:
def generic_query_pattern(sess, class_, pk):
# ..generic logic I wish to reuse..
instance = sess.query(class_).get(pk)
# ..more generic logic involving instance..
return instance
Adding logic for the eagerload there would be my absolute last ditch
solution since it would be so messy and defeat the "generic" part.
Hence why I'm wondering if it's possible to do it by only accessing the
instance "a":
a = generic_query_pattern(sess, A, a_key)
# Do something here, so that a pattern like this..
abcs = [ each_b.c for each_b in a.b ]
# ..isn't O(n) queries
Or, since I'm being more concrete now, if there is some other way to
architect generic_query_pattern such that I can accomplish this, I'm
open to that too.
-Kyle
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