On Apr 5, 2011, at 9:06 AM, Israel Ben Guilherme Fonseca wrote:
> Hi,
>
> Is it possible to break a table in two Python objects? Ex:
>
> Python objects:
>
> class Person:
>
> name = Column(String)
>
> class Address:
>
> street = Column(String)
> city = Column(String)
>
>
> Table:
>
> table Person
> name varchar
> city varchar
> street varchar
>
> How can i make the "connection" between the two?
You could map Person and Address both to the table, excluding/including columns
from each using mapper "include_properties/exclude_properties" (see the docs),
however relationship() would not be able to handle the join condition of this
table, which is table.id==table.id.
So in the practical sense, you'd just do this:
class Person(object):
@property
def address(self):
return Address(self.street, self.city)
or similarly use a composite (search the mapping documentation for "composite")
to achieve the Address class composed of that subset of columns. If you
choose "composite" I'd note 0.7 improves upon the scalability of the
"composite" feature significantly (for small datasets in memory it doesn't
matter though).
> And is it possible to make the inverse? (table Person and Address to a single
> Python object Person)
you can map to a join of the two tables as described at
http://www.sqlalchemy.org/docs/orm/mapper_config.html#mapping-a-class-against-multiple-tables.
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