On Friday, November 11, 2016 at 2:22:28 PM UTC, Simon King wrote: > > On Fri, Nov 11, 2016 at 1:53 PM, Michael Williamson <mic...@healx.io > <javascript:>> wrote: > > > >> I think your code is basically fine, you've just got a mistake on the > >> last line. Presumably you meant to query Person, not Person.born? > > > > > > I want Person.born so that I don't have to get the entire object. It > doesn't > > make much difference in this example, but is quite important for us in > > practice when we're grabbing multiple expressions. > > > >> > >> hybrid_property does't care about the name of the "fget" function, it > >> just calls it, passing the instance as the only parameter: > >> > >> > >> > https://bitbucket.org/zzzeek/sqlalchemy/src/f2eb4aac9517a3775411c2ecf0f588ffd0d790f6/lib/sqlalchemy/ext/hybrid.py?at=master&fileviewer=file-view-default#hybrid.py-744 > > >> > > > > The call to util.update_wrapper sets the property to have the same name > as > > the fget function, which in turn is used when creating the SQL > expression > > (the self.__name__ expression in the comparator method), which > determines > > the label of the value in the result object. > > > > OK, I'm probably missing something. I don't have access to PG right > now, so I couldn't run your code directly. Having said that, I'm > surprised that the comparator object is even invoked in the > expression: > > session.query(Person.born).one().born == '1881' > > ...because "session.query(Person.born).one()" returns a tuple-ish > object with 1 element, which won't have a "born" attribute. >
It's a namedtuple-ish object -- it behaves as a tuple, but you can also get values out by name. The comparator is invoked during construction of the hybrid property. Specifically, the constructor calls self.expression, which then calls self.comparator. > Anyway, to answer your original question, would it be sufficient to > update the __name__ attribute of your instance_get function inside > json_property? > > ie. > > def json_property(json_column, name, type_=None): > def instance_get(self): > return getattr(self, json_column.key)[name] > instance_get.__name__ = name > Unfortunately not: the JSON property may not have the same name as the attribute e.g. year_born = json_property(data, "yearBorn", Integer()) > Simon > -- SQLAlchemy - The Python SQL Toolkit and Object Relational Mapper http://www.sqlalchemy.org/ To post example code, please provide an MCVE: Minimal, Complete, and Verifiable Example. See http://stackoverflow.com/help/mcve for a full description. --- 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.
