Hello guys!
I am trying to join two models by relationship, but I want to emulate
values of second model using from_statement.
class X(Base):
__tablename__ = 'x'
id = Column(Integer, primary_key=True)
class Y(Base):
__tablename__ = 'y'
id = Column(Integer, primary_key=True)
x_id = Column(Integer, ForeignKey(X.id))
x = relationship(X)
Y1 = aliased(Y, name='y1')X1 = Query(X).from_statement(select([label('id',
literal(5))])).subquery(name='x1')session.query(Y1).join(X1, Y.x).all()
Here
<https://bitbucket.org/zzzeek/sqlalchemy/issues/4274/join-queryfrom_statement#comment-46063178>
Michael
Bayer suggested to do the following:
Y1 = aliased(Y, name=‘y1’)
stmt = select([label(‘id’, literal(5))])
X1 = Query(X).from_statement(stmt).subquery(name=‘x1’)
session.query(Y1).join(X1, stmt.alias(“x1”).c.id == Y1.id).all()
But in that case I would need to convert relationship Y.x to corresponding
ON clause.
Is it possible to do that automatically? I.e. For any relationship derive
corresponding ON clause?
Thanks in advance!
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