Why isn't SQLAlchemy default column value available before object is committed?

Question

Recently I figured out that SQLAlchemy\'s Column default doesn\'t work as I expect it to:

>>> Base = declarative_base()
>>> class TestModel         


        

Answer 1

You can use force_instant_defaults listener from sqlalchemy_utils to change this behavior:

from sqlalchemy_utils import force_instant_defaults

force_instant_defaults()

class TestModel(Base):
    __tablename__ = 'tmodel'
    id = sa.Column(sa.Integer, primary_key=True)
    foo = sa.Column(sa.Integer, default=0)

model = TestModel()
assert model.foo == 0