Flask_wtf - UnmappedInstanceError: Class is not mapped - flask

Question

I'm building a relatively simple Flask application with a not so simple database. I've a lot of models to handle and relate all the needed information in the DB.
For some reason I'm getting the title error.
I'm starting to think is some how related with my DB models/relationships.
So, the implementation of the models goes as the follow:
from app import db, login
from werkzeug.security import generate_password_hash, check_password_hash
from flask_login import UserMixin
import datetime
class User(UserMixin, db.Model):
id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String(64), index=True, unique=True)
email = db.Column(db.String(120), index=True, unique=True)
password = db.Column(db.String(128))
def set_password(self, password):
self.password = generate_password_hash(password)
def check_password(self, passwd):
return check_password_hash(self.password, passwd)
def __repr__(self):
return '<User {}>'.format(self.username)
class airFeedVariator(db.Model):
variatorID = db.Column(db.Integer, db.ForeignKey('variator.id',onupdate='RESTRICT',ondelete='RESTRICT'), primary_key=True)
airFeedID = db.Column(db.Integer, db.ForeignKey('air_feed.id',onupdate='RESTRICT',ondelete='RESTRICT'), primary_key=True)
variatorRel = db.relationship('Variator', backref='variators',lazy='joined')
freq = db.Column(db.Integer)
class Variator(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(30))
machineID = db.Column(db.Integer)
baudrate = db.Column(db.Integer)
addedAt = db.Column(db.DateTime, default=datetime.datetime.utcnow) # the current timestamp
class Air_feed(db.Model):
id = db.Column(db.Integer, primary_key=True)
timeOn = db.Column(db.Integer)
timeOff = db.Column(db.Integer)
desc = db.Column(db.String)
digital = db.relationship('Pin_function', backref='analog_or_digital', lazy=True)
airFeedTypeId = db.relationship('Air_feed_type', backref='air_feed_type_id', lazy=True, uselist=False) #This allow the usage for a single element. 1-1 Rel.
#variators = db.relationship('Variator', secondary=airFeedVariator, lazy='subquery',backref=backref('airfeedvariators', lazy=True))
variators = db.relationship('airFeedVariator', lazy='dynamic')
And the forms goes as:
from flask_wtf import FlaskForm
from wtforms import StringField, PasswordField, BooleanField, SubmitField, IntegerField, DateTimeField
from wtforms.validators import ValidationError, DataRequired, Email, EqualTo
from flask_babel import lazy_gettext as _l #compile in runtime only.
#Utilizado para converter directamente os modelos em forms.
#from wtforms_alchemy import ModelForm
from app import models
from wtforms_alchemy import model_form_factory
BaseModelForm = model_form_factory(FlaskForm)
class ModelForm(BaseModelForm):
#classmethod
def get_session(self):
print('Session: ', db.session)
return db.session
class LoginForm(FlaskForm):
username = StringField(_l('Utilizador'), validators=[DataRequired()])
password = PasswordField(_l('Password'), validators=[DataRequired()])
remember_me = BooleanField(_l('Lembrar-me'))
submit = SubmitField(_l('Submeter'))
class RegistrationForm(FlaskForm):
username = StringField('Username', validators=[DataRequired()])
email = StringField('Email', validators=[DataRequired(), Email()])
password = PasswordField('Password', validators=[DataRequired()])
password2 = PasswordField(
'Repetir Password', validators=[DataRequired(), EqualTo('password')])
submit = SubmitField(l_('Registo'))
#Validate on submit check for this. The rise allow to write a message directly on the webpage!
def validate_username(self, username):
user = models.User.query.filter_by(username=username.data).first()
if user is not None:
raise ValidationError(_l('Utilizador já existente!'))
def validate_email(self, email):
user = models.User.query.filter_by(email=email.data).first()
if user is not None:
raise ValidationError(_l('Email já existente!'))
class VariatorForm(FlaskForm):
name = StringField(_l('Nome'), validators=[DataRequired()])
machineID = IntegerField(_l('Identificador'), validators=[DataRequired()])
baudrate = IntegerField(_l('Valocidade Comm'), validators=[DataRequired()])
addedAt = DateTimeField(_l('Preenchimento automatico')) # the current timestamp
def validate_machineID(self, machineID):
user = models.Variator.query.filter_by(machineID=machineID.data).first()
if user is not None:
raise ValidationError(_l('Já existente um variador registado neste endereço!'))
I do realize that I have a FlaskForm form and ModelForm on the others, I was just testing.
My problem is the following:
File "c:\app\routes.py", line 49, in SaveVariator
db.session.add(var) File "c:\gburner\lib\site-packages\sqlalchemy\orm\scoping.py", line 153, in do
return getattr(self.registry(), name)(*args, **kwargs) File "c:\gburner\lib\site-packages\sqlalchemy\orm\session.py", line 1833, in add
raise exc.UnmappedInstanceError(instance) sqlalchemy.orm.exc.UnmappedInstanceError: Class 'app.forms.VariatorForm' is not mapped
* Added Problatic route.py part *
#app.route('/savevariator', methods=['POST'])
def SaveVariator():
var = VariatorForm(request.form)
if var.validate_on_submit():
print('Variator form submit accepted!')
### I was doing this ### Trying to add the FORM to the session!
db.session.add(var)
db.session.commit()
#############################
### INSTEAD I Should be doing this: ######
variator = Variator(name=var.name, machineID=var.machineID, baudrate=var.baudrate)
db.session.add(variator)
db.session.commit()
##############################
resp = jsonify(success=True)
else:
print('Variator form submit NOT accepted!')
resp = jsonify(success=False)
return resp
I think html code would not be necessary since everything works fine until the moment where the call to save information on database happens.
Am I missing something regarding the mapping relationship in database because I have 3 tables for a many to many relationship?
Any help solve the problem would greatly appreciated.
Thank you.
* EDIT *
Thanks to Joost for point me this simple yet difficult to realize point! (I probably should pause more often).

Answer 1

The problem was in the route section:
#app.route('/savevariator', methods=['POST'])
def SaveVariator():
var = VariatorForm(request.form)
if var.validate_on_submit():
print('Variator form submit accepted!')
### I was doing this ### Trying to add the FORM to the session!
db.session.add(var)
db.session.commit()
#############################
### INSTEAD I Should be doing this: ######
variator = Variator(name=var.name, machineID=var.machineID, baudrate=var.baudrate)
db.session.add(variator)
db.session.commit()
##############################
resp = jsonify(success=True)
else:
print('Variator form submit NOT accepted!')
resp = jsonify(success=False)
return resp
Thanks to Joost I was able to understand where the problem was. Thanks again!
I realize it's a simple mistake, but I couldn't find much information regarding the error and solution. However if the admins decide it's not worth to keep, feel free to remove it.
Thank you.