[Grok-dev] Modeling a class that extend from list() with megrok.rdb

[Hector Blanco]

Got it... It was just that it was treating "children_table.id" as an string...

I also asked in the sqlalchemy and I got an answer... Maybe someone
may find it useful:
http://groups.google.com/group/sqlalchemy/browse_thread/thread/c1d46daf35116999?hide_quotes=no#msg_e4d879b47892aea1

2010/10/29 Hector Blanco <white.lists at gmail.com>:
> Hello list...
>
> I thing I almost have it, but I am still getting problems mapping an
> structure like this.
>
> class Child(rdb.Model):
>       def __init__(self):
>               self.field1 = “hello world”
>
> class Parent(rdb.Model):
>       def __init__(self):
>               self.child1 = Child()
>               self.child2 = Child()
>
> (I have modified it from the former question because maybe it'll be
> easy to understand)
>
> The “Parent” class has two different instances of a Child() class. I
> am not even sure about how to treat this (two different 1:1
> relationships or a 1:2 relationship).
>
> My last try (out of many) is this mapping:
>
> class Child(rdb.Model):
>       rdb.metadata(metadata)
>       rdb.tablename("children_table")
>       id = Column("id", Integer, primary_key=True)
>       field1 = Column(“field1”, String(64))   #Irrelevant
>       def __init__(self):
>               self.field1 = “hello world”
>
> class Parent(rdb.Model):
>       rdb.metadata(metadata)
>       rdb.tablename("parent_table”)
>
>       id = Column("id", Integer, primary_key=True)
>       child1_id = Column("child_1_id", Integer,
> ForeignKey("children_table.id"))
>       child2_id = Column("child_2_id", Integer,
> ForeignKey("children_table.id"))
>
>       child1 = relationship(Child,
>               primaryjoin = (child1_id=="children_table.id")
>       )
>
>       child2 = relationship(Child,
>               primaryjoin = (child2_id=="children_table.id")
>       )
>
> I have tried (almost) everything. I say “almost” because obviously I
> haven't tried the right thing. I keep getting errors that sqlalchemy
> can't determine the relationship between the two tables.
>
> It looks very similar to:
> http://www.sqlalchemy.org/docs/orm/relationships.html#multiple-relationships-against-the-same-parent-child
>
> but I also understand that maybe I can't get this working that way,
> because I am actually putting two ForeignKeys from the same table
> (“children_table”) in the parent table. I am not sure how that will
> work out, or is correct or what... :-(
>
> Thank you!
>