from sqlalchemy import func
from datetime import date
my_data = session.query(MyObject).filter(
func.date(MyObject.date_time) == date.today()
).all()
qry = DBSession.query(User).filter(
and_(User.birthday <= '1988-01-17', User.birthday >= '1985-01-17'))
# or same:
qry = DBSession.query(User).filter(User.birthday <= '1988-01-17').
filter(User.birthday >= '1985-01-17')