Define models in seperate file when using app factory flask - flask

Question

I am creating a flask application where I am using the app factory method. I have a file in the application folder __init__.py which has the create_app function with the following code
def create_app(test_config=None):
app = Flask(__name__,instance_relative_config=True)
app.config.from_mapping(
SECRET_KEY='dev',
)
app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql+pymysql://root:#localhost/database'
db = SQLAlchemy(app)
if test_config == None:
app.config.from_pyfile('config.py',silent=True)
else:
app.config.form_mapping(test_config)
from flaskr import models
try:
os.makedirs(app.instance_path)
except OSError:
pass
class User(db.Model):
id = db.Column(db.Integer,primary_key=True)
uname = db.Column(db.String(50))
#app.route('/hello')
def hello():
return json.dumps({'message':'hello','status':True})
#app.route('/getusers')
def getusers():
u = User.query.get(1)
return json.dumps({'uname':u.uname})
return app
What I want is to define the models in a seperate file. How can I do this?
I have tried defining in a seperate file and importing it. But the problem is the model inherits the db.Model which is then not available in the imported file.

Answer 1

Leave the creation of db object outside create_app without passing any app instance and use the SQLAlchemy.init_app method to configure and init. your db object, this way you can import it from any file:
db = SQLAlchemy()
#...
def create_app(test_config=None):
app = Flask(__name__,instance_relative_config=True)
#...
db.init_app(app)
More on this topic can be found at flask's documentation

Answer 2

I've fought with this problem a few hours too. Couldn't fix it until I came to the realization, that I have to return the app inside the app.app_context()
model.py:
from flask_user import UserMixin
from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy()
class User(db.Model, UserMixin):
__tablename__ = 'users'
id = db.Column(db.Integer, primary_key=True)
email = db.Column(db.String(255, collation='NOCASE'), nullable=False,
unique=True)
# ...
__init__.py:
from flask import Flask
from flask_migrate import Migrate
def create_app(test_config=None):
app = Flask(__name__, instance_relative_config=True)
app.config.from_pyfile('config.py', silent=True)
migrate = Migrate()
from appname.model import db
db.init_app(app)
migrate.init_app(app, db)
with app.app_context():
# Create all database tables
db.create_all()
import appname.routes
# Apply the blueprints to the app
from appname import bp1, bp2
appname.register_blueprint(bp1.bp)
appname.register_blueprint(bp2.bp)
return app
Run with:
cd ~/Folder/Webapp
. appname/bin/activate
export FLASK_APP=appname
export FLASK_ENV=development
flask run
(in Linux terminal)
or create this file and run it in python shell:
from appname import create_app
if __name__ == '__main__':
app = create_app()
app.run(debug=True)