Hello;
I have recently started on a project using SQLAlchemy, and have run into
a problem when trying to join a row in one table to two separate rows in
another.
I am working on an application in which users can send messages to each
other. I have two tables, a User table, and a Item table. They look as
follows:
tm_user = Table("user", engine,
Column('userid', String(5), primary_key=True,
...
)
tm_item = Table("item", engine,
Column("itemid", String(5), primary_key=True),
...
Column('from_uid', String(5), ForeignKey("user.userid")),
Column('to_uid', String(5), ForeignKey("user.userid"))
)
Each Item is associated with two Users: the sender ('from_uid') and the
recipient ('to_uid'). I have set up mappers like this:
map_item = mapper(Item, tm_item)
map_user = mapper(User, tm_user,
properties = {
'outbox' :
relation(mapper(Item,primaryjoin=tm_user.c.userid==Item.c.from_uid)),
'inbox' : relation(mapper(Item,
primaryjoin=tm_user.c.userid==Item.c.to_uid)),
}
)
The problem with this is that, when I create a User object with a query
and inspect its inbox and outbox properties, I find that each one
contains only Items where both from_uid and to_uid are equal to userid.
How can I change this so that outbox only matches by from_uid and inbox
by to_uid?
Thanks,
Andrew Bulhak
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