Hello Martin,
you can use the uselist=False parameter
From the doc :
The |backref()| function is often used to set up a bi-directional
one-to-one relationship. This is because the |relation()| function by
default creates a "one-to-many" relationship when presented with a
primary key/foreign key relationship, but the |backref()| function can
redefine the |uselist| property to make it a scalar
Regards,
Julien
Martin Stein wrote:
> Hi everybody,
>
> In my project, I would like to use a table setup similar to the following one:
>
> users= Table('users', metadata,
> Column('id', Integer, primary_key=True),
> Column('name', String(50)),
> ...
> )
>
> user_data = Table('user_data', metadata,
> Column('id', Integer, ForeignKey("contexts.id"), primary_key=True),
> Column('password', String(20)),
> ...
> )
>
> It is a one to one-relationship, because each user only has one user_data
> column. It would be nice, if I could map this kind of relationship in a way
> similar to the one-to-one example of the documentation. So, in my
> corresponding User-object, I would like to be able to access the userData
> part like this, for example:
>
> user.userData.password
>
> But, when I map my one-to-one relation like this:
>
> UserData.mapper = mapper(UserData, user_data, properties = {
> 'id' : user_data.c.id,
> 'password' : user_data.c.password,
> }
> )
>
> User.mapper = mapper(User, users, properties = {
> 'id' : users.c.id,
> 'name' : users.c.name,
> 'userData' : relation(UserData,
> cascade="all, delete-orphan")
> }
> )
>
> then the mapper interpretes the relationship as one-to-many, thus mapping
> userData with a list like behaviour, for example:
> user.userData[0].password
>
> This is just a minor issue for me, but still... is there maybe an easy way to
> tell the mapper that it is a one-to-one relationship and not one-to-many?
> (I would like to avoid generating a separate primary key for my user_data (in
> contrast to the user_preferences example of the docs))
>
> ... oh, and a second short question: is the SmallInteger column type broken?
>
> Thanks and cheers,
> Martin
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Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
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