Re: [sqlalchemy] sqlalchemy.exc.InvalidRequestError: Mapper properties (i.e. deferred,column_property(), relationship(), etc.) must be declared as @declared_attr callables on declarative mixin classes.

[Michal Petrucha]

Hi Andreas,

On Fri, Jan 15, 2016 at 02:56:39AM -0800, Andreas Jung wrote:
> Hi,
> 
> I currently have the following mix-in class construction (based on the 
> documentation 
> http://docs.sqlalchemy.org/en/latest/orm/extensions/declarative/mixins.html
> )
> 
> Base = declarative_base() 
> 
> class BaseCountry(object): 
>    """ Managed through Kotti """ 
> 
>    @declared_attr 
>    def __tablename__(cls): 
>        return cls.__name__.lower() 
> 
>    dpis_id = Column(Integer, primary_key=True) 
>    title =  Column(Unicode(80)) 
>    regions = relationship("Region", 
>                             primaryjoin="Country.dpis_id==Region.country_id") 

As the error message in the exception says, this attribute needs to be
declared as a declared_attr, like this:
    
    @declared_attr
    def regions(cls):
        return relationship("Region", 
                            primaryjoin="Country.dpis_id==Region.country_id") 

This is stated in the following section of the docs:
http://docs.sqlalchemy.org/en/latest/orm/extensions/declarative/mixins.html#mixing-in-relationships

Good luck,

Michal

>    "Mapper properties (i.e. deferred," 
> sqlalchemy.exc.InvalidRequestError: Mapper properties (i.e. 
> deferred,column_property(), relationship(), etc.) must be declared as 
> @declared_attr callables on declarative mixin
> classes.

-- 
You received this message because you are subscribed to the Google Groups 
"sqlalchemy" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to sqlalchemy+unsubscr...@googlegroups.com.
To post to this group, send email to sqlalchemy@googlegroups.com.
Visit this group at https://groups.google.com/group/sqlalchemy.
For more options, visit https://groups.google.com/d/optout.

signature.asc
Description: Digital signature