Flask-Migrate sqlalchemy.exc.NoReferencedTableError: Foreign key associated with column - sqlalchemy

Question

I am using Flask-Migrate in my application, with the following models:
listpull/models.py
from datetime import datetime
from listpull import db
class Job(db.Model):
id = db.Column(db.Integer, primary_key=True)
list_type_id = db.Column(db.Integer, db.ForeignKey('listtype.id'),
nullable=False)
list_type = db.relationship('ListType',
backref=db.backref('jobs', lazy='dynamic'))
record_count = db.Column(db.Integer, nullable=False)
status = db.Column(db.Integer, nullable=False)
sf_job_id = db.Column(db.Integer, nullable=False)
created_at = db.Column(db.DateTime, nullable=False)
compressed_csv = db.Column(db.LargeBinary)
def __init__(self, list_type, created_at=None):
self.list_type = list_type
if created_at is None:
created_at = datetime.utcnow()
self.created_at = created_at
def __repr__(self):
return '<Job {}>'.format(self.id)
class ListType(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(80), unique=True, nullable=False)
def __init__(self, name):
self.name = name
def __repr__(self):
return '<ListType {}>'.format(self.name)
run.py
#!/usr/bin/env python
# -*- coding: utf-8 -*-
from listpull import app, manager
manager.run()
listpull/__init__.py
from flask import Flask
from flask.ext.sqlalchemy import SQLAlchemy
from flask.ext.script import Manager
from flask.ext.migrate import Migrate, MigrateCommand
from mom.client import SQLClient
from smartfocus.restclient import RESTClient
app = Flask(__name__)
app.config.from_object('config')
db = SQLAlchemy(app)
migrate = Migrate(app, db)
manager = Manager(app)
manager.add_command('db', MigrateCommand)
...
import listpull.models
import listpull.views
I initialized the database using ./run.py db init and then I run ./run.py db migrate and I get the following error:
sqlalchemy.exc.NoReferencedTableError: Foreign key associated with column 'job.list_type_id' could not find table 'listtype' with which to generate a foreign key to target column 'id'
What am I doing wrong here?

Answer 1

You are letting Flask-SQLAlchemy choose the names for your tables. If I remember correctly, for a class called ListType the table name will be list_type (or something similar), not the listtype that you specified in your foreign key.
My recommendation is that you specify your own table names using __tablename__, that way they are explicit in the code and not magically determined for you. For example:
class Job(db.Model):
__tablename__ = 'jobs'
id = db.Column(db.Integer, primary_key=True)
list_type_id = db.Column(db.Integer, db.ForeignKey('list_types.id'),
nullable=False)
# ...
class ListType(db.Model):
__tablename__ = 'list_types'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(80), unique=True, nullable=False)
# ...

Answer 2

I was looking for a solution for similar information problem you deal with for a long time as well... at the end, the solution i found was add into every "table-class" the line __tablename__ = '<your_table_name>'
it seems to help flask to find your table

Answer 3

In my case, the issue was that i accidentally called the foreign key by the class name vs the table name ...
Like: db.Column(db.Integer, db.ForeignKey('ClassListTypes.id') vs db.Column(db.Integer, db.ForeignKey('list_types.id')