Re: [sqlalchemy] another quick question regarding abstract classes
thanks again Mike! i'll work this here :) my best regards, richard. On 06/10/2014 07:14 PM, Mike Bayer wrote: On Tue Jun 10 15:36:09 2014, Richard Gerd Kuesters wrote: so, here i am again with another weird question, but it may be interesting for what it may come (i dunno yet). the problem: i have a collection of abstract classes that, when requested, the function (that does the request) checks in a internal dictionary if that class was already created or creates it by using declarative_base(cls=MyAbstractClass), that later can have an engine and then work against a database. i use this format because i work with multiple backends from multiple sources, so abstract classes are a *must* here. now, the problem: foreign keys and relationships. it's driving me nuts. ok, let's say I have 2 classes, Foo and Bar, where Bar have one FK to Foo. class Foo(object): __abstract__ = True foo_id = Column(...) ... class Bar(object): __abstract__ = True foo_id = Column(ForeignKey(...)) /(those classes are just examples and weren't further coded because it's a conceptual question)/ i know that the code might be wrong, because i can use @declared_attr here and furthermore help sqlalchemy act accordingly (i don't know if this is the right way to say it in english, but it is not a complain about sqlalchemy actions). ok, suppose I created two subclasses, one from each abstract model (Foo and Bar) in a postgres database with some named schema, let's say sc1. we then have sc1.foo and sc1.bar. now, i want to create a third table, also from Bar, but in the sc2 schema, where its foreign key will reference sc1.foo, which postgres supports nicely. how can i work this out, in a pythonic and sqlalchemy friendly way? does @declared_attr solves this? or do I have to map that foreign key (and furthermore relationships) in the class mapper, before using it, like a @classmethod of some kind? @declared_attr can help since the decorated function is called with cls as an argument. You can look on cls for __table_args__ or some other attribute if you need, and you can create a Table on the fly to serve as secondary, see http://docs.sqlalchemy.org/en/rel_0_9/_modules/examples/generic_associations/table_per_related.html for an example of what this looks like. best regards and sorry for my english, richard. -- 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 mailto:sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com mailto:sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout. -- 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 http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
[sqlalchemy] another quick question regarding abstract classes
so, here i am again with another weird question, but it may be interesting for what it may come (i dunno yet). the problem: i have a collection of abstract classes that, when requested, the function (that does the request) checks in a internal dictionary if that class was already created or creates it by using declarative_base(cls=MyAbstractClass), that later can have an engine and then work against a database. i use this format because i work with multiple backends from multiple sources, so abstract classes are a *must* here. now, the problem: foreign keys and relationships. it's driving me nuts. ok, let's say I have 2 classes, Foo and Bar, where Bar have one FK to Foo. class Foo(object): __abstract__ = True foo_id = Column(...) ... class Bar(object): __abstract__ = True foo_id = Column(ForeignKey(...)) /(those classes are just examples and weren't further coded because it's a conceptual question)/ i know that the code might be wrong, because i can use @declared_attr here and furthermore help sqlalchemy act accordingly (i don't know if this is the right way to say it in english, but it is not a complain about sqlalchemy actions). ok, suppose I created two subclasses, one from each abstract model (Foo and Bar) in a postgres database with some named schema, let's say sc1. we then have sc1.foo and sc1.bar. now, i want to create a third table, also from Bar, but in the sc2 schema, where its foreign key will reference sc1.foo, which postgres supports nicely. how can i work this out, in a pythonic and sqlalchemy friendly way? does @declared_attr solves this? or do I have to map that foreign key (and furthermore relationships) in the class mapper, before using it, like a @classmethod of some kind? best regards and sorry for my english, richard. -- 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 http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
Re: [sqlalchemy] another quick question regarding abstract classes
On Tue Jun 10 15:36:09 2014, Richard Gerd Kuesters wrote: so, here i am again with another weird question, but it may be interesting for what it may come (i dunno yet). the problem: i have a collection of abstract classes that, when requested, the function (that does the request) checks in a internal dictionary if that class was already created or creates it by using declarative_base(cls=MyAbstractClass), that later can have an engine and then work against a database. i use this format because i work with multiple backends from multiple sources, so abstract classes are a *must* here. now, the problem: foreign keys and relationships. it's driving me nuts. ok, let's say I have 2 classes, Foo and Bar, where Bar have one FK to Foo. class Foo(object): __abstract__ = True foo_id = Column(...) ... class Bar(object): __abstract__ = True foo_id = Column(ForeignKey(...)) /(those classes are just examples and weren't further coded because it's a conceptual question)/ i know that the code might be wrong, because i can use @declared_attr here and furthermore help sqlalchemy act accordingly (i don't know if this is the right way to say it in english, but it is not a complain about sqlalchemy actions). ok, suppose I created two subclasses, one from each abstract model (Foo and Bar) in a postgres database with some named schema, let's say sc1. we then have sc1.foo and sc1.bar. now, i want to create a third table, also from Bar, but in the sc2 schema, where its foreign key will reference sc1.foo, which postgres supports nicely. how can i work this out, in a pythonic and sqlalchemy friendly way? does @declared_attr solves this? or do I have to map that foreign key (and furthermore relationships) in the class mapper, before using it, like a @classmethod of some kind? @declared_attr can help since the decorated function is called with cls as an argument. You can look on cls for __table_args__ or some other attribute if you need, and you can create a Table on the fly to serve as secondary, see http://docs.sqlalchemy.org/en/rel_0_9/_modules/examples/generic_associations/table_per_related.html for an example of what this looks like. best regards and sorry for my english, richard. -- 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 mailto:sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com mailto:sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout. -- 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 http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
