I'm trying to get the id from an object that is trapped in a self-referential relationship. I believe my definition of the relationship may be limiting its function, or perhaps I'm projecting. I've tried every related SO solution I could find to no avail. Mainly, the form.parent_id.data.parent_id pattern I've seen on several solutions throws AttributeError: 'NoneType' object has no attribute 'parent_id'. I'm aware that sqlalchemy.exc.InterfaceError: <unprintable InterfaceError object> results from form.parent_id.data because QuerySelectField returns an object, not an id. I get the same error when setting get_pk=lambda x: x.parent_id in the form object.
routes.py
def edit_user(id):
form = UserForm()
user = User.query.get_or_404(id)
selected_date_ids = []
upcoming_dates = TestDate.query.order_by(TestDate.date).filter(TestDate.status != 'past')
tests = sorted(set(TestDate.test for TestDate in TestDate.query.all()), reverse=True)
if form.validate_on_submit():
if request.method == "POST":
...
user.tutor_id=form.tutor_id.data
user.parent_id=form.parent_id.data
models.py
class User(UserMixin, db.Model):
id = db.Column(db.Integer, primary_key=True)
...
tutor_id = db.Column(db.Integer, db.ForeignKey('user.id'))
students = db.relationship('User', backref=db.backref('tutor'),
foreign_keys=[tutor_id], remote_side=[id])
parent_id = db.Column(db.Integer, db.ForeignKey('user.id'))
children = db.relationship('User', backref=db.backref('parent'),
foreign_keys=[parent_id], remote_side=[id])
forms.py
def get_tutors():
return User.query.filter_by(role='tutor')
def get_parents():
return User.query.filter_by(role='parent')
def full_name(User):
return User.first_name + " " + User.last_name
class UserForm(FlaskForm):
...
tutor_id = QuerySelectField('Tutor', default=1, query_factory=get_tutors, get_label=full_name, allow_blank=True)
parent_id = QuerySelectField('Parent', query_factory=get_parents, get_label=full_name, allow_blank=True)
is_admin = BooleanField('Admin')
submit = SubmitField('Save')
