Hello, i'm supporting legacy database, and using such models (code contains examples of my problem, keep reading):
class Product: # This table is never used straightforward in queries type = Column(db.Integer) name = Column(db.String) TYPE_GUITARS = 1 TYPE_DRUMS = 2 __tablename__ = 'product' __mapper_args__ = { 'polymorphic_on': type, } class Guitars(Product): __mapper_args__ = { 'polymorphic_identity': Product.TYPE_GUITARS, # Guitars entity } class Drums(Product): __mapper_args__ = { 'polymorphic_identity': Product.TYPE_DRUMS, # Drums entity } # This query returns nothing. query1 = session.query(Musician).filter( Musician.guitar == Guitars.id, Musician.drum == Drums.id, ) # Because SQL query built is wrong: # select * ... *from product* where ... => no rows returned # To fix his i use aliased() function: guitars = aliased(Guitars, name='guitars') drums = aliased(Drums, name='drums') query2 = session.query(Musician).filter( Musician.guitar == guitars.id, Musician.drum == drums.id, ) # select * ... *from product as guitars, product as drums* where ... => working fine My problem is that when i'm using two Polymorphic Models (with one database table) i always must use aliased() function. This is demonstrated in example higher. As you can see, query1 produces no results, because it is selecting from *products* table, and applies two filters to it. Instead it should use *two product table aliases. *It can be achieved with using *aliased()* function. So, finally, my question is: Are there any mechanism in sqlalchemy that can automatically apply aliases to such tables, if it sees their combination in query? -- 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.