Question

I’m attempting to load a User object from mysql but I keep getting UnboundExecutionError: Could not locate a bind configured on mapper Mapper|UserDo|user, SQL expression or this Session. I’m using classical mappings.

Base = declarative_base()

# A default constructor is created if one is not already present,
# which accepts keyword arguments of the same name as that of the mapped attributes.

class UserDo(Base):
    __tablename__ = 'user'

    id = Column(Integer, primary_key = True)
    fname = Column(String(100))
    lname = Column(String(100))
    email = Column(String(200))
    salt = Column(String(100))
    created_on = Column(TIMESTAMP) # from sqlalchemy.dialects.mysql import TIMESTAMP

class BaseService(object):

    def __init__(self):
        self._engine = create_engine('mysql://root@localhost/my_db', pool_recycle = 3600)
        self._Session = sessionmaker(bind = self._engine)
        self._session = Session()

class UserService(BaseService):

    def create(self, data):
        print self._session.query(UserDo).first() # Error

I’m wondering if I’m getting the error because of my create_engine statement. Maybe I’m not supplying the correct format for the connection. I don’t have a password for my local database.

Also, something else that I noticed:
print self._session.query(UserDo)

prints SELECT “user”.id AS user_id, “user”.fname AS user_fname, “user”.lname AS user_lname, “user”.email AS user_email, “user”.salt AS user_salt, “user”.created_on AS user_created_on
FROM “user”

Which is a syntactically incorrect. Either way I don’t care what SQLAlchemy is doing internally, as long as doing User.fname, User.lname (etc), works as defined.

Anyone see what’s going on?

Answer 1

For some reason SQLAlchemy 0.8 doesn’t like it when I do this (creating instance variables):

class BaseService(object):

    def __init__(self):
        self._engine = create_engine('mysql://root@localhost/my_db', pool_recycle = 3600)
        self._Session = sessionmaker(bind = self._engine)
        self._session = Session()

The fix was to make them static instead:

class BaseService(object):
    engine = create_engine('mysql://root@localhost/my_db', pool_recycle = 3600)
    Session = sessionmaker(bind = engine)
    session = Session()

Then you can do:

class UserService(BaseService):

    def create(self, data):
        BaseService.session.query(UserDo).first()