On Jul 4, 2011, at 3:25 PM, Michael Tils wrote:
> Here is my mapping, this time in german...
OK, sifting through lots of extraneous details as well as the lack of the
actual table definitions, it seems like you're looking to join from
Building->BuildingCondition->Lookup.
I don't use aliased=True very often, but I think its usage pattern would allow
this:
lc1 = aliased(LookupSubclassOne)
lc2 = aliased(LookupSubclassTwo)
query(Building).\
join(Building.condition,aliased=True).\
join(lc1, BuildingCondition.rating, from_joinpoint=True).\
join(Building.condition, aliased=True).\
join(lc2, BuildingCondition.care_level, from_joinpoint=True).\
filter(...)
I don't talk about aliased=True often because it has a specific effect on
subsequent modifications to the query, which are then reset on the next call to
join(), and its a little confusing/hard to explain. In this case, the second
and fourth calls to join() add from_joinpoint=True so that it goes from the
previous joinpoint.
For a full explicit approach, just alias everything:
bc1 = aliased(BuildingCondition)
bc2 = aliased(BuildingCondition)
lc1 = aliased(LookupSubclassOne)
lc2 = aliased(LookupSubclassTwo)
query(Building).\
join(bc1, Building.condition).\
join(lc1, bc1.rating).\
join(bc2, Building.condition).\
join(lc2, bc2.care_level).\
filter(...)
note I'm using the 0.7 style of joins here where you can say join(target,
onclause) without an embedded tuple.
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