Naming conventions

gistfile1.py

class SurveySection(db.Model):
    """
    Survey_section has a one-to-many relationship with User_survey_section
    """
    id = db.Column(db.Integer, primary_key=True)
    user_survey_sections = db.relationship('User_survey_section', backref="survey_section",
            lazy='dynamic')
    name = db.Column(db.String(45))

class UserSurveySection(db.Model):
    """
    User_survey_section has a many-to-one relationship with Survey_section
    """
    id = db.Column(db.Integer, primary_key=True)
    survey_section_id = db.Column(db.Integer, db.ForeignKey('survey_section.id'))
    completed_date = db.Column(db.DateTime)

gistfile2.pytb

In [13]: User.query.filter_by(email="")
---------------------------------------------------------------------------
InvalidRequestError                       Traceback (most recent call last)
<ipython-input-13-c505348c33f2> in <module>()
----> 1 User.query.filter_by(email="")

/home/drew/.virtualenvs/staging/local/lib/python2.7/site-packages/flask_sqlalchemy.pyc in __get__(self, obj, type)
    392     def __get__(self, obj, type):
    393         try:
--> 394             mapper = orm.class_mapper(type)
    395             if mapper:
    396                 return type.query_class(mapper, session=self.sa.session())

/home/drew/.virtualenvs/staging/local/lib/python2.7/site-packages/sqlalchemy/orm/util.pyc in class_mapper(class_, compile)
    659 
    660     if compile and mapperlib.module._new_mappers:
--> 661         mapperlib.configure_mappers()
    662     return mapper
    663 

/home/drew/.virtualenvs/staging/local/lib/python2.7/site-packages/sqlalchemy/orm/mapper.pyc in configure_mappers()
   2258                             % mapper._configure_failed)
   2259                     e._configure_failed = mapper._configure_failed
-> 2260                     raise e
   2261                 if not mapper.configured:
   2262                     try:

InvalidRequestError: One or more mappers failed to initialize - can't proceed with initialization of other mappers.  Original exception was: When initializing mapper Mapper|SurveySection|survey_section, expression 'User_survey_section' failed to locate a name ("name 'User_survey_section' is not defined"). If this is a class name, consider adding this relationship() to the <class 'petalapp.database.models.SurveySection'> class after both dependent classes have been defined.