> map_column is shorthand for this:
>
> table = Table('sometable', metadata,
> ...
> Column('somecolumn', ...)
> )
>
> mapper(Class, table, properties= {
> '_somecolumn':table.c.somecolumn,
> 'somecolumn':synonym('_somecolumn')
>
> })
>
> so the argument does not apply to your "parent" relation since its not
> a column-based attribute, its a relation(). Also the small snip you
> sent didn't seem to have any need for a synonym on parent, unless
> there are other properties in your code that weren't part of what you
> sent.
So, should I delete the column_prefix from the code I sent, and change
the code in the calls to synonym()? (following the mapper code)
mapper(Resource, resources,
polymorphic_on=resources.c.type,
polymorphic_identity="empty",
column_prefix='_',
properties={
'id': resources.c.id,
'url': synonym('_url', map_column=True),
'children': relation(Resource, backref=backref("_parent",
remote_side=[resources.c.id])),
'parent': synonym('_parent', map_column=True),
'name': synonym('_name', map_column=True),
'type': resources.c.type,
# NOTE: Remember to add here other columns that don't need
# a custom property accessor, like the id. Otherwise, they
# be available as _column_name, not column_name.
},
save_on_init=False,
)
I do have properties for url (this is the example I sent), parent and
name.
When I deleted map_column from 'parent': synonym('_parent',
map_column=True) and imported the module everything was all right. But
when I run my tests (basically just creating a Resource() object and
setting properties to see if the code in them work properly), it
raises and exception:
File "[...]/model/resources.py", line 118, in _set_url
self.parent.save()
AttributeError: 'Resource' object has no attribute 'parent'
Which only happens when I try to access Resource().parent.*; when I
"print repr()" Resource().parent there is no problem... Apparently
this problem is only with parent.
Thanks.
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