Re: [Sqlalchemy-tickets] [sqlalchemy] #2887: subqueryload query invokes ahead of parent loader init, can cause conflicts

[sqlalchemy <mi...@zz...>]

#2887: subqueryload query invokes ahead of parent loader init, can cause conflicts
------------------------------+-------------------------------
      Reporter:  zzzeek       |      Owner:  zzzeek
          Type:  defect       |     Status:  new
      Priority:  high         |  Milestone:  0.8.xx
     Component:  orm          |   Severity:  major - 1-3 hours
    Resolution:               |   Keywords:
Progress State:  in progress  |
------------------------------+-------------------------------

Comment (by zzzeek):

 whew, no problem, that was just because we were testing _dict being empty,
 which it might be anyway, here's an even more crude "with a flag" thing,
 obviously need to clean this up:

 {{{
 #!diff
 diff --git a/lib/sqlalchemy/orm/strategies.py
 b/lib/sqlalchemy/orm/strategies.py
 index 8226a0e..2f20040 100644
 --- a/lib/sqlalchemy/orm/strategies.py
 +++ b/lib/sqlalchemy/orm/strategies.py
 @@ -937,12 +937,22 @@ class SubqueryLoader(AbstractRelationshipLoader):
          # call upon create_row_processor again
          collections = path.get(context.attributes, "collections")
          if collections is None:
 -            collections = dict(
 -                    (k, [vv[0] for vv in v])
 -                    for k, v in itertools.groupby(
 -                        subq,
 -                        lambda x: x[1:]
 -                    ))
 +            flag = [0]
 +            _data = dict()
 +            #subq = list(subq)
 +            class X(object):
 +                def get(self, key, default):
 +                    if not flag[0]:
 +                        flag[0] = 1
 +                        _data.update(
 +                            (k, [vv[0] for vv in v])
 +                            for k, v in itertools.groupby(
 +                                subq,
 +                                lambda x: x[1:]
 +                            )
 +                        )
 +                    return _data.get(key, default)
 +            collections = X()
              path.set(context.attributes, 'collections', collections)

          if adapter:
 }}}

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Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2887#comment:3>
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