Hey Jonathan,
The reason this doesn't work is because you're supplying to a
select query an instance object, when it's expecting either column types,
actual values, or some other clause element. The actual error, I think,
relates to 'type' being your LazyLoader property, and not an actual column! :)
One way to write the query would be to use a proper Clause construct. You can
see an example of this in the Basic Data Mapping section at:
http://www.sqlalchemy.org/docs/index.myt?paged=no#datamapping_relations_lazyload_relselectby
and also at:
http://www.sqlalchemy.org/docs/index.myt?paged=no#datamapping_selecting
For your case, I imagine it might look like something as simple as:
myInstance = model.Instance.mapper.select_by(
instance.c.name == 'primary_email',
instance_type.c.name == 'email')
Hope that helps!
Cheers!
-G
On Wednesday, April 26, 2006, 2:25:01 AM, you wrote:
> Hi all,
> I've done the svn tutorial as suggested + gone through the
> datamapping / advanced data mapping 3x each.
> I seem to be ok on the SELECTs with sqlalchemy, but still having
> trouble with the writes.
> Specifically I keep running into a wall on this one issue:
> Going back to my example, again its simple, I just can't figure this
> out based on the docs ( it thought it would have been similar to
> http://sqlalchemy.org/docs/datamapping.myt#datamapping_onetoone or
> myInstance = model.Instance.mapper.select_by(
> name = 'primary_email',
> type = model.InstanceType.mapper.select_by( name = 'email' )
> )
> Trying that, I get
> AttributeError: 'LazyLoader' object has no attribute 'columns'
> I thought 'maybe I should try it with eager loader or property
> loader?' same thing.
> ------
> instance_type = Table('instance_type', __engine__,
> Column('id', Integer, primary_key=True),
> Column('name', String(255) , unique=instance_type_name_idx' ),
> )
> instance = Table('instance', __engine__,
> Column('id', Integer, primary_key=True),
> Column('instance_type_id' , Integer , ForeignKey
> ("instance_type.id") ),
> Column('name', String(255) , unique='instance_name_idx' ),
> )
> class Instance(object):
> pass
> class InstanceType(object):
> pass
> InstanceType.mapper = mapper( InstanceType , instance_type )
> Instance.mapper = mapper( Instance , instance ,
> properties = {
> 'type' : relation( InstanceType.mapper ) ,
> }
> )
> ----
> i also tried
> ----
> Instance.mapper = mapper( Instance , instance ,
> properties = {
> 'type' : relation( mapper(InstanceType , instance_type ) ),
> }
> )
> ----------
> If anyone can make a suggestion, I'd be grateful.
> -------------------------------------------------------
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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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