this feature should be added and is http://www.sqlalchemy.org/trac/ticket/2700,
here's a workaround for now:
from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.ext.declarative import declarative_base
class FixTableArgs(object):
@classmethod
def __declare_last__(cls):
if '__extra_table_args__' in cls.__dict__:
cls.__table__._init_items(*cls.__extra_table_args__)
del cls.__extra_table_args__
Base = declarative_base(cls=FixTableArgs)
class BaseClass(Base):
__tablename__ = "base"
id = Column(Integer, primary_key=True)
base_col = Column(Integer)
__table_args__ = (Index("ix1", base_col),)
class SubClass(BaseClass):
col_a = Column(Integer)
col_b = Column(Integer)
__extra_table_args__ = (UniqueConstraint("col_a", "col_b"), )
configure_mappers()
print BaseClass.__table__.constraints
On Apr 9, 2013, at 5:38 AM, "Gombas, Gabor (IT)"
<[email protected]> wrote:
> Hi,
>
> What is the recommended method of specifying constraints on columns
> added by a subclass using single-table inheritance? This does not work,
> I get a KeyError for "col_a":
>
> class BaseClass(Base)
> __table__ = "base"
> __table_args__ = (Index("base_col"),
> UniqueConstraint("col_a", "col_b"))
>
> base_col = Column(Integer)
>
> class SubClass(BaseClass):
> col_a = Column(Integer)
> col_b = Column(Integer)
>
> SQLA does not allow __table_args__ placed on SubClass. I can do a
> workaround by using BaseClass.__table__.append_constraint() after
> defining SubClass, but mixing different ways of defining constraints
> does not look nice.
>
> Gabor
>
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