I created a Flask app with SQLAlchemy.
I initialised the database in app.py but I want to use it in another file: otherfile.py.
app.py
app = Flask(__name__)
app.config['JSONIFY_PRETTYPRINT_REGULAR'] = True
app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///my_database'
db = SQLAlchemy(app)
print("TEST")
otherfile.py
from app import db
print(db)
But I get the error.
ImportError: cannot import name 'db'
Basically, I am doing this because I do not want to write the SQLAlchemy logic in app.py but I want to keep it in another file.
In addition, I just want the variable db to be exported. I do not want that when I run otherfile.py, this runs also print("TEST") which is in app.py
I looked at these answer with little luck:
How to share the global app object in flask?
Split Python Flask app into multiple files
How to divide flask app into multiple py files?
The SQLAlchemy class doesn't need to receive the app param on its initialization. So what you can do is create the db object in your otherfile.py and import it in app.py, where you can pass it the app object with SQLAlchemy.init_app().
app.py
from flask import Flask
from otherfile import db
app = Flask(__name__)
app.config['JSONIFY_PRETTYPRINT_REGULAR'] = True
app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///my_database'
db.init_app(app)
otherfile.py
from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy()
Related
I am trying to run the server of this repository (it's about oauth2): https://github.com/lepture/flask-oauthlib/blob/master/tests/oauth2/server.py
The main file looks like this:
if __name__ == '__main__':
from flask import Flask
app = Flask(__name__)
app.debug = True
app.secret_key = 'development'
app.config.update({
'SQLALCHEMY_DATABASE_URI': 'sqlite:///test.sqlite'
})
app = create_server(app)
app.run()
However, I am getting this error:
Error: Failed to find Flask application or factory in module 'hello'. Use 'FLASK_APP=hello:name' to specify one.
I executed the following commands in terminal:
export FLASK_APP=server.py` and
export FLASK_APP=main.py
After that, I tried rerunning with flask run
Again, I am getting this error:
Error: Failed to find Flask application or factory in module 'main'. Use 'FLASK_APP=main:name' to specify one.
Try this code
from flask import Flask
app = Flask(__name__)
app.debug = True
app.secret_key = 'development'
app.config.update({
'SQLALCHEMY_DATABASE_URI': 'sqlite:///test.sqlite'
})
if __name__ == '__main__':
app.run(host="0.0.0.0", port="5000", debug=True)
You should run it directly
python server.py
And if you want to use flask run then you would have to put all (except app.run()) before if __name__ == '__main__': because flask run will import this file and import will skip code inside if __name__ == '__main__':
# ... other code ...
from flask import Flask
app = Flask(__name__)
app.debug = True
app.secret_key = 'development'
app.config.update({
'SQLALCHEMY_DATABASE_URI': 'sqlite:///test.sqlite'
})
app = create_server(app)
if __name__ == '__main__':
app.run()
And it will need export FLASK_APP=server:app because you want to run file server.py and use instance of Flask() with name app
export FLASK_APP=server:app
flask run
Because code uses standard name app so you could skip it in export
export FLASK_APP=server
flask run
You can also run without export
flask --app server run
Try this one:
But I recommend you to start with the basics before work with databases. Try to render HTML templates, use bootstrap, etc. You are running here. Anyway, this boilerplate works for me.
import os
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_migrate import Migrate
app = Flask(__name__)
# Key for Forms
app.config['SECRET_KEY'] = 'mysecretkey'
# SQL DATABASE AND MODELS
basedir = os.path.abspath(os.path.dirname(__file__))
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///' + os.path.join(basedir, 'data.sqlite')
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
db = SQLAlchemy(app)
Migrate(app, db)
class Puppy(db.Model):
__tablename__ = 'puppies'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.Text)
def __init__(self, name):
self.name = name
#app.route('/')
def index():
return '<h1>Hello Puppy!</h1>'
if __name__ == '__main__':
app.run(debug=True)
I've rummaged through maybe 50 different answers to this and still I haven't manage to fix it... I'm pretty new to flask and python.
I have an app which was running great locally but I've struggled with deploying on python anywhere. Initially I had a few import modules issues, now it runs but doesn't return any html template, despite not seeing any other issue. The main issue I had was that it couldn't find the "routes" app from wsgi, and I sort of fixed adding the app = Flask(name) line on routes.py (the short blueprint object is not callable).
routes.py:
from flask import Blueprint, render_template, request, redirect, send_file
import pyqrcode
from pyqrcode import QRCode
import subprocess
from extensions import db
from models import Link
app = Flask(__name__)
short = Blueprint('short', __name__, url_prefix='/')
#short.route('/index')
def index():
return render_template('index.html')
init.py
from flask import Flask
from extensions import db
from routes import short
def create_app(config_file='settings.py'):
app = Flask(__name__)
app.config.from_pyfile(config_file)
db.init_app(app)
app.register_blueprint(short)
return app
wsgi.py
import sys
# add your project directory to the sys.path
project_home = u'/home/b297py/mysite'
if project_home not in sys.path:
sys.path = [project_home] + sys.path
# import flask app but need to call it "application" for WSGI to work
from routes import app as application
For the purpose of testing, I've placed all the html templates both in the root directory and in the specific /template directory but it just didn't fix the issue.
In wsgi.py you are not calling create_app so you are never registering the blueprint. You should replace :
from routes import app as application
by something like :
from package_name import create_app
application = create_app()
(Example: https://www.pythonanywhere.com/forums/topic/12889/#id_post_50171)
Also as you mentioned, the fix adding app = Flask(__name__) to routes.pyallows you to bypass create_app (so you should remove it if you want to stick to the create_app approach).
I have the following project structure:
project/__init__.py
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_migrate import Migrate
db = SQLAlchemy()
migrate = Migrate()
def create_app():
app = Flask(__name__)
app.config.from_object(os.environ['APP_SETTINGS'])
db.init_app(app)
migrate.init_app(app, db)
return app
run.py
from project import create_app
app = create_app()
if __name__ == "__main__":
app.run()
manage.py
from flask_script import Manager
from flask_migrate import MigrateCommand
from project.models import *
from project import create_app
manager = Manager(create_app)
manager.add_command('db', MigrateCommand)
if __name__ == '__main__':
manager.run()
Yet when I run the following commands, Flask-Migrate is not detecting any tables to be added.
python manage.py db init
Which outputs:
Creating directory $HOME/Project/migrations ... done
Creating directory $HOME/Project/migrations/versions ... done
Generating $HOME/Project/migrations/script.py.mako ... done
Generating $HOME/Project/migrations/env.py ... done
Generating $HOME/Project/migrations/README ... done
Generating $HOME/Project/migrations/alembic.ini ... done
Please edit configuration/connection/logging settings in
'$HOME/Project/migrations/alembic.ini' before proceeding.
and
python manage.py db migrate
Which only outputs:
INFO [alembic.runtime.migration] Context impl PostgresqlImpl.
INFO [alembic.runtime.migration] Will assume transactional DDL.
Why is Flask-Migrate with Alembic not detecting the Models and therefore creating the tables? Here's what I've tried:
Deleting the database, starting from nothing
Creating a custom db class inside the manage.py file, doesn't detect that
Googling every answer to this problem, found lots of similar questions but none of their solutions worked for me.
EDIT:
Here is an example of the models.py file
from flask import current_app
from project import db
from flask_login import UserMixin
class User(db.Model, UserMixin):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(50))
The solution was to import the models in the __init__.py file like so:
def create_app():
app = Flask(__name__)
app.config.from_object(os.environ['APP_SETTINGS'])
from project import models
db.init_app(app)
migrate.init_app(app, db)
return app
I had the same issue. The solution is pretty same as #joe's
In routes file
from models import User
api_user = Namespace('user', description='user related operations')
In project/__init__.py
def create_app():
app = Flask(__name__)
app.config.from_object(os.environ['APP_SETTINGS'])
from project import models
db.init_app(app)
migrate.init_app(app, db)
blueprint = Blueprint('api', __name__, url_prefix=url_prefix)
api = Api(blueprint, doc='/documentation') # ,doc=False
app.register_blueprint(blueprint)
api.add_namespace(api_user)
return app
when adding api_user namespace in create_app flask_migrate detected models
Here is my migration file :
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_script import Manager
from flask_migrate import Migrate, MigrateCommand
import models
app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///' + 'C:\\flaskDB\\commBorn3.db'
db = SQLAlchemy(app)
migrate = Migrate(app, db)
manager = Manager(app)
manager.add_command('db', MigrateCommand)
if __name__ == '__main__':
manager.run()
I ran the standard commands :
python app.py db init
python app.py db migrate
python app.py db upgrade
The resulting database was a file of the same name with about the same size in kb but only one table, "alembic_version" which had nothing in it. I tried to downgrade and found all my tables returned but they were empty. What did I do wrong? Where is all the data hiding (same kb size of file)?
You should always check the migration file in migrations/versions created after db migrate, and execute db upgrade only when everything looks alright.
The problem is that in models.py you import a db = SQLAlchemy(app) instance from your "normal" app, not from the migration script. So in the migration script you actually don't define any model, and this is why it deletes all your tables in the database.
The solution is easy: just use the migration script's app context when you import the models:
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_script import Manager
from flask_migrate import Migrate, MigrateCommand
app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///' + 'C:\\flaskDB\\commBorn3.db'
db = SQLAlchemy(app)
# Import database models with app context
with app.app_context():
from models import *
migrate = Migrate(app, db)
manager = Manager(app)
manager.add_command('db', MigrateCommand)
if __name__ == '__main__':
manager.run()
I'm beginning to learn python and I'm following this tutorial on setting up Flask, but I'm having some trouble understanding the author in how he lays out his files. From what I can gather, it seems like I'm running into a circular import problem and I can't trouble shoot it.
The files are set up as follows:
__init__.py
from flask import Flask
app = Flask(__name__)
app.config['SECRET_KEY'] = "something here";
app.config['SQLALCHEMY_DATABASE_URI'] = "sqlite://app.db"
app.py
from flask import render_template, request, redirect, url_for, abort, session
from app import app
#app.route('/')
.... some stuff here
models.py
from flask.ext.sqlalchemy import SQLAlchemy
from app import app
db = SQLAlchemy(app)
class User(db.Model):
.... some stuff here
manage.py
#!/usr/bin/env python
from flask.ext.script import Manage, Shell, Server
from app import app
manage = Manager(app)
manager.add_command("runserver", Server())
manager.add_command("shell", Shell())
#manager.command
def createdb():
from app.models import db
db.create_all()
manager.run()
The first error is being unable to start the server through running manage.py runserver. I was able to do it initially until I switched the files around initialized the app within init.py (originally I had everything located in app.py). I receive an error saying -
ImportError: cannot import name app
That aside, if I eliminate init.py and get the server up and running, I can't create a database because I receive an error stating -
Import Error: no module named models when running manage.py createdb