On Dec 16, 2005, at 11:24 PM, limodou wrote:
User.mapper = mapper(Mapper, users, properties = dict(
relation(Address.mapper, lazy=True, private=True)
))
yah where are you seeing that? I think all those are fixed unless
you can point me to one
And I also cann't distinguish the differences between OneToMany and
OneToOne, in the mapping code. Can someone show me the differences
between them in code?
Ill show you just where is happens, the thing is I used a bizarre
naming convention when I first wrote it (using LEFT, RIGHT, and
CENTER to mean "one-to-many", "many-to-one", and "many-to-many"),
which is probably why you didnt see it. I might change the
convention to be more sane.
the general determination of "direction" is here:
http://www.sqlalchemy.org/trac/browser/sqlalchemy/trunk/lib/
sqlalchemy/mapping/properties.py#L105
the three important methods in determining this are:
_match_primaries: determine the JOIN conditions of the parent
mapper's table to the child mapper's table. it does this by looping
through the foreign keys for both tables and seeing if they reference
the other table. If we have an association table, we run the method
on that one too to figure out the "secondary join". This method will
also try to determine which column in the JOIN condition is the
foreign key column, i.e. the one that references the primary key of
the other table, and sets that as our "foreign key" property, which
indicates what kind of relationship we are.
http://www.sqlalchemy.org/trac/browser/sqlalchemy/trunk/lib/
sqlalchemy/mapping/properties.py#L200
_find_dependent: If are not a many-to-many, and we dont yet know
what column in our primary JOIN condition is the "foreign key" (maybe
because the JOIN condition was explicitly specified and we didnt get
to call _match_primaries), which column in the JOIN condition is the
"foreign key" that references a primary key? if there are multiple,
we just need to find one of them.
http://www.sqlalchemy.org/trac/browser/sqlalchemy/trunk/lib/
sqlalchemy/mapping/properties.py#L180
_get_direction: based on our primary join and our foreign key, are we
the "right" side in a parent/child relationship (many to one), or the
"left" (one to many)? or do we have an association table (a
"secondary" join), and we are neither of those, er, what should I
call that...how about "center" (hence the goofy names)?
http://www.sqlalchemy.org/trac/browser/sqlalchemy/trunk/lib/
sqlalchemy/mapping/properties.py#L167
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