I'm trying to write a select query which joins two tables. Let's say
the first table is called 'users' and has a column called 'user_id'.
Let's say the second table is called 'addresses' and has a two-column
composite primary key on the columns ('user_id', 'address_type'). The
'address_type' column would be something like home, work, etc.
Now I want to OUTER join these two tables where the user_id's are
equal but the address_type is a constant (for example, I'm only
interested in 'home' addresses right now). I tried doing this by:
outerjoin(User, Address, and_(User.c.user_id == Address.c.user_id,
Address.c.address_type == bindparam('addr_type'))
Unfortunately, this produces the following error:
>> Module sqlalchemy.sql:2293 in _init_primary_key
>> if p.references(c) or (c.primary_key and not p.primary_key):
exceptions.AttributeError: '_BindParamClause' object has no attribute
'primary_key'
I tried moving the "address_type == bindparam('addr_type')" clause to
the "where" clause instead of the join condition, which winds up
building a workable query, but unfortunately this query is not
equivalent to the one I actually want. The problem is that, let's say
I'm looking for 'home' addresses and the addresses table contains an
address of type 'work' for user_id 1 but not one of type 'home'. When
using the (non-working in sqlalchemy) outerjoin above, I should get a
result row with all of the selected address columns as NULL, but when
using the substituted "where" version, I get no rows returned at all
(because the join condition matches the 'work' row, but then the
"where" clause filters it out).
Is this a bug in SQLAlchemy, or am I doing something wrong? I'm using
SQLAlchemy 0.3.10. Thanks.
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