Peewee select with circular dependency - foreign-key-relationship

Question

I have two models Room and User. Every user is assigned to exactly one room and one of them is the owner.
DeferredUser = DeferredRelation()
class Room(Model):
owner = ForeignKeyField(DeferredUser)
class User(Model):
sessid = CharField()
room = ForeignKeyField(Room, related_name='users')
DeferredUser.set_model(User)
Now, having sessid of the owner I'd like to select his room and all assigned users. But when I do:
(Room.select(Room, User)
.join(User, on=Room.owner)
.where(User.sessid==sessid)
.switch(Room)
.join(User, on=User.room))
It evaluates to:
SELECT "t1".*, "t2".* # skipped column names
FROM "room" AS t1
INNER JOIN "user" AS t2 ON ("t1"."owner_id" = "t2"."id")
INNER JOIN "user" AS t2 ON ("t1"."id" = "t2"."room_id")
WHERE ("t2"."sessid" = ?) [<sessid>]
and throws peewee.OperationalError: ambiguous column name: t2.id as t2 is defined twice.
What I actually need to do is:
room = (Room.select(Room)
.join(User.sessid=sessid)
.get())
users = room.users.execute()
But this is N+1 query and I'd like to resolve it in a single query like:
SELECT t1.*, t3.* FROM room AS t1
INNER JOIN user AS t2 ON t1.owner_id = t2.id
INNER JOIN user as t3 ON t3.room_id = t1.id
WHERE t2.sessid = ?;
Is there a peewee way of doing this or I need to enter this SQL query by hand?

Answer 1

You need to use a model alias when you are using the same table in two different contexts. So:
Owner = User.alias() # Create a model alias.
(Room.select(Room, Owner, User)
.join(Owner, on=(Room.owner == Owner.id))
.where(Owner.sessid == sessid)
.switch(Room)
.join(User, on=User.room))
http://docs.peewee-orm.com/en/latest/peewee/api.html?#Model.alias