On Aug 9, 2010, at 6:26 PM, Alvaro Reinoso wrote:
> Hello,
>
> I have these classes:
>
>class Channel(rdb.Model):
> rdb.metadata(metadata)
> rdb.tablename("channels")
>
> id = Column("id", Integer, primary_key=True)
> title = Column("title", String(100))
>
>
> items = relationship("MediaItem", secondary=channel_items,
> order_by="MediaItem.titleView", backref="channels")
>
>class MediaItem(rdb.Model):
> rdb.metadata(metadata)
> rdb.tablename("media_items")
>
> id = Column("id", Integer, primary_key=True)
> title = Column("title", String(100))
>
>class User(rdb.Model):
> rdb.metadata(metadata)
> rdb.tablename("users")
>
> id = Column("id", Integer, primary_key=True)
> name = Column("name", String(50))
>
> channels = relationship("Channel", secondary=user_channels,
> order_by="Channel.titleView", backref="users")
>
> MediaItem is related to Channel and Channel is related to User.
>
> if I'd like to select some columns from items and channels, I'd do
> this:
>
>session = Session()
>result =
> session.query(Channel).join(Channel.items).values(Channel.title,
> Item.title)
>
> I get an instance of Channel class with its items.
>
> My problem is I don't know how to select some columns from User,
> Channel and Item. How can I make a query where for example, I can
> select the User.name property and its channels with only Channel.title
> property and the items of those channels with only Item.title
> property?
the form illustrated in the second example of
http://www.sqlalchemy.org/docs/ormtutorial.html#querying selects individual
columns, as does the "values()" method you're already using (i.e.
values(User.name, Channel.title, Item.title) ). You'd also want to add an
extra join for "Channel.users".
--
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To post to this group, send email to sqlalch...@googlegroups.com.
To unsubscribe from this group, send email to
sqlalchemy+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/sqlalchemy?hl=en.
