Mapper Errors while creating Rows - flask

Question

I'm working on building a recipe database. In this, there are ingredients (like onions, carrots, etc) and modifiers (like diced, peeled, etc) which are in part of ModifiedIngredients which is part of a recipe. My models.py is as follows:
from app import db
modifiers = db.Table('modifiers',
db.Column('modified_ingredient', db.Integer, db.ForeignKey('modified_ingredient.id')),
db.Column('modifier', db.Integer, db.ForeignKey('modifier.id'))
)
modified_ingredients = db.Table('modified_ingredients',
db.Column('recipe', db.Integer, db.ForeignKey('recipe.id')),
db.Column('modified_ingredient', db.Integer, db.ForeignKey('modified_ingredient.id'))
)
class Recipe(db.Model):
__tablename__ = 'recipe'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(256))
description = db.Column(db.Text)
directions = db.Column(db.Text)
prep_time = db.Column(db.Integer)
cook_time = db.Column(db.Integer)
image = db.Column(db.LargeBinary())
ingredients = db.relationship('modified_ingredient', secondary=modified_ingredients)
class Ingredient(db.Model):
__tablename__ = 'ingredient'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(30), index=True, unique=True)
class Modifier(db.Model):
__tablename__ = 'modifier'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(30), index=True, unique=True)
class ModifiedIngredient(db.Model):
__tablename__ = 'modified_ingredient'
id = db.Column(db.Integer, primary_key=True)
amount = db.Column(db.Integer)
unit = db.Column(db.String(20))
ingredients = db.relationship('ingredient', backref='ingredient', lazy='dynamic')
modifiers = db.relationship('Modifier', secondary=modifiers,
backref=db.backref('modifiers', lazy='dynamic'), lazy='dynamic')
recipe = db.Column(db.Integer, db.ForeignKey('recipe.id'))
However, if I open up a shell and enter in something like "onion = models.Ingredient(name='Onion')" I get the error:
sqlalchemy.exc.InvalidRequestError: One or more mappers failed to initialize - can't proceed with initialization of other mappers. Original exception was: relationship 'ingredients' expects a class or a mapper argument (received: <class 'sqlalchemy.sql.schema.Table'>)
I'm not exactly sure where my setup is going wrong.
Thanks.

Answer 1

if i'm reading the error message correctly then
ingredients = db.relationship('modified_ingredient', secondary=modified_ingredients)
should become
ingredients = db.relationship('ModifiedIngredient', secondary=modified_ingredients)
Note in the error message:
Original exception was: relationship 'ingredients' expects a class or a mapper argument (received: <class 'sqlalchemy.sql.schema.Table'>)
If it expects a class, give it a class :)