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Flask & SQL ALchemy, the created Database has an unknown Type

I am currently writing a program in python using flask and flask_sqlalchemy. I have done the same steps as in the documentation. But when the database gets created automatically, it has an unknown file type, altough it should be a sqlite database. I am using Pycharm btw.
from flask import Flask, render_template, request, redirect
from flask_sqlalchemy import SQLAlchemy
# create the extension
db = SQLAlchemy()
# create the app
app = Flask(__name__)
# configure the SQLite database, relative to the app instance folder
app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:///filemanager.db"
# initialize the app with the extension
db.init_app(app)
class File(db.Model):
id = db.Column(db.Integer, primary_key=True)
path = db.Column(db.String, unique=True, nullable=False)
type = db.Column(db.String, unique=False, nullable=False)
#app.route('/', methods=['GET', 'POST'])
def index():
return render_template('index.html')
if __name__ == '__main__':
create_database = True
if create_database:
with app.app_context():
db.create_all()
app.run(debug=True, port=5008)
I tried to change the file type manually to sqlite, but it still doesn't contain tables and columns. If I create the columns manually in the console everything works, but I have and want to do it programmatically.
I also tried another stackoverflow answer, where he split the code into two files, didn't work eiter.
Thanks in advance!

The problem was the name of the Database and the name of the table. I had "filemanager.db" and "files", these names don't work (don't ask me why), but I tried with "users.db" and "users" and it works

How to use instance file in flask

I am using SQLalchemy to create my db in flask. For this I create a project.db file and run the following code :
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
# create the extension
db = SQLAlchemy()
# create the app
app = Flask(__name__)
# configure the SQLite database, relative to the app instance folder
app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:///project.db"
# initialize the app with the extension
db.init_app(app)
class User(db.Model):
id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String, unique=True, nullable=False)
email = db.Column(db.String)
with app.app_context():
db.create_all()
When I run create_table, it creates me a new folder named instance and a new project.db file in it. The result is that my first project.db does not work and is useless.
What must I do then ? Because when looking at different topic and videos this never happens. Thanks in advance !

Where is project.db located? Keep it in the same folder as the script, or try using an absolute path like this?
app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:////absolute/path/to/project.db"

db.create_all() not generating db

I'm trying to test Flask with SQLAlchemy and I stumbeld accross this problem. First, I have to note that I read all of the related threads and none of them solves my problem. I have a problem that db.create_all() doesn't generate the table I defined. I have model class in file person.py:
from website import db
class Person(db.Model):
id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String, nullable=False)
password = db.Column(db.String)
width = db.Column(db.Integer)
height = db.Column(db.Integer)
agent = db.Column(db.String)
user_data_dir = db.Column(db.String)
And in my website.py which is the file from where I launch the app:
from flask import Flask, jsonify, render_template, request
from flask_sqlalchemy import SQLAlchemy
# create the extension
db = SQLAlchemy()
def start_server(host, port, debug=False):
from person import Person
# create the app
app = Flask(__name__,
static_url_path='',
static_folder='web/static',
template_folder='web/templates')
# configure the SQLite database, relative to the app instance folder
app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:///database0.db"
# initialize the app with the extension
db.init_app(app)
print('initialized db')
print('creating tables...')
with app.app_context():
db.create_all()
db.session.add(Person(username="example33"))
db.session.commit()
person = db.session.execute(db.select(Person)).scalar()
print('persons')
print(person.username)
if __name__ == '__main__':
start_server(host='0.0.0.0', port=5002, debug=True)
I think the problem might be that the Person class is not importing properly, because when I put the class inside the start_server function it executes fine and creates the table, but I don't know why this is happening. I followed all the advice and imported it before everything, and also I share the same db object between the 2 files

There is probably a better way to do this but this is the only way I could get this to work. You need to create a models.py file or w.e you wanna call it. Then all your database stuff goes in there. The db engine, ALL your models and a function to initialize it all. The reason is, you are having import issues where Person is imported but not fully and so the db doesn't have it in its metadata.
models.py
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy()
class Person(db.Model):
id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String, nullable=False)
password = db.Column(db.String)
width = db.Column(db.Integer)
height = db.Column(db.Integer)
agent = db.Column(db.String)
user_data_dir = db.Column(db.String)
# All other models
def initialize_db(app: Flask):
db.init_app(app)
with app.app_context():
db.create_all()
main.py
from flask import Flask
import models
def start_server(host, port, debug=False):
app = Flask(__name__)
# configure the SQLite database, relative to the app instance folder
app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:///database0.db"
# initialize the app with the extension
models.initialize_db(app)
db = models.db
with app.app_context():
db.session.add(models.Person(username="example33"))
db.session.commit()
person = db.session.execute(db.select(models.Person)).scalar()
print('persons')
print(person.username)
if __name__ == '__main__':
start_server(host='0.0.0.0', port=5002, debug=True)

I am reading the documentation,
which explains that the function will
Create all tables stored in this metadata.
That leads me to believe Person is not associated with the db metadata.
You mentioned
when I put the class inside the start_server function it ... creates the table
Your from person import Person is nice enough,
but I suspect we wanted a simple import person.
In many apps the idiom would be import models.
Failing that, you may be able to point
create_all in the right direction
with this optional parameter:
tables – Optional list of Table objects, which is a subset of the total tables in the MetaData
Please let us know
what technical approach worked for you.

Why does my database get reset after each deployment?

I am new to deploying to aws as well as flask. Basically I have a simple Flask app but every time I make a change and deploy the new code to aws elastic beanstalk, the db gets reset.
from dateutil import parser
from datetime import datetime
from flask import Flask, request, jsonify
from flask_sqlalchemy import SQLAlchemy
from flask_marshmallow import Marshmallow
from flask_cors import CORS
import os
application = app = Flask(__name__)
basedir = os.path.abspath(os.path.dirname(__file__))
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///' + os.path.join(basedir, 'db.sqlite')
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = True
db = SQLAlchemy(app)
ma = Marshmallow(app)
cors = CORS(app)
#app.route('/')
def hello():
return 'hello'
.
.
.
class User(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String)
weight = db.Column(db.Float)
workouts = db.relationship('Workout', backref='user', lazy=True)
def __init__(self, name, weight):
self.name = name
self.weight = weight
class UserSchema(ma.Schema):
class Meta:
fields = ('id', 'name', 'weight')
user_schema = UserSchema(strict=True)
users_schema = UserSchema(many=True, strict=True)
.
.
.
db.create_all()
if __name__ == '__main__':
app.run(debug=True)
I expect that each time I
eb deploy flask-env my db wouldnt get reset but it does. For instance if i create a user and then later change something in the code and deploy, that user is gone.

You should:
Create an EBS Volume
Load the database into that volume
Attach the EBS Volume to your Beanstalk app with an .ebextension. An example can be found here.
With all that being said, this is not a highly available, well architected solution and will deteriorate at scale rapidly.
You will want to replace SQLite with an RDS instance at some point in the future before it becomes a problem.

using Flask-Migrate together with Flask-Security

I'm trying to get a basic Flask-Security app working with Flask-Migrate. I have two main py files: app.py and db_migrate.py
app.py:
from flask import Flask, render_template, request, session
from flask.ext.babel import Babel
from flask.ext.mail import Mail
from flask.ext.sqlalchemy import SQLAlchemy
from flask.ext.security import Security, SQLAlchemyUserDatastore, UserMixin, RoleMixin
import os
basedir = os.path.abspath(os.path.dirname(__file__)) #should be __ file __ with no spaces
# Create app
app = Flask(__name__)
app.config['DEBUG'] = True
app.config['SECRET_KEY'] = 'super-secret'
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///' + os.path.join(basedir, 'app.db')
app.config['DEFAULT_MAIL_SENDER'] = 'info#site.com'
app.config['SECURITY_REGISTERABLE'] = True
app.config['SECURITY_CONFIRMABLE'] = True
app.config['SECURITY_RECOVERABLE'] = True
app.config.from_object('config.email')
# Setup mail extension
mail = Mail(app)
# Setup babel
babel = Babel(app)
#babel.localeselector
def get_locale():
override = request.args.get('lang')
if override:
session['lang'] = override
rv = session.get('lang', 'en')
return rv
# Create database connection object
db = SQLAlchemy(app)
# Setup Flask-Security
from db_manager import User, Role #THIS IS PROBABLY WRONG!
user_datastore = SQLAlchemyUserDatastore(db, User, Role)
security = Security(app, user_datastore)
#db.create_all()
# Views
#app.route('/')
def home():
return render_template('index.html')
if __name__ == '__main__':
app.run()
db_migrate.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 flask.ext.sqlalchemy import SQLAlchemy
from flask.ext.security import Security, SQLAlchemyUserDatastore, UserMixin, RoleMixin
import os
basedir = os.path.abspath(os.path.dirname(__file__))
app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///' + os.path.join(basedir, 'app.db')
db = SQLAlchemy(app)
migrate = Migrate(app, db)
manager = Manager(app)
manager.add_command('db', MigrateCommand)
# Define models
roles_users = db.Table('roles_users',
db.Column('user_id', db.Integer(), db.ForeignKey('user.id')),
db.Column('role_id', db.Integer(), db.ForeignKey('role.id')))
class Role(db.Model, RoleMixin):
id = db.Column(db.Integer(), primary_key=True)
name = db.Column(db.String(80), unique=True)
description = db.Column(db.String(255))
class User(db.Model, UserMixin):
id = db.Column(db.Integer, primary_key=True)
email = db.Column(db.String(255), unique=True)
password = db.Column(db.String(255))
active = db.Column(db.Boolean())
confirmed_at = db.Column(db.DateTime())
favcolor = db.Column(db.String(255))
roles = db.relationship('Role', secondary=roles_users,
backref=db.backref('users', lazy='dynamic'))
def __str__(self):
return '<User id=%s email=%s>' % (self.id, self.email)
if __name__ == '__main__':
manager.run()
I have run the migration tool to initialize and migrate the db once, to create a new db, and it worked:
python db_manager.py db init
python db_manager.py db migrate
I tried to run app.py. It serves correctly on localhost, but then when I try to log a user in, I get the following OperationalError:
OperationalError: (OperationalError) no such table: user u'SELECT user.id AS user_id, user.email AS user_email, user.password AS user_password, user.active AS user_active, user.confirmed_at AS user_confirmed_at, user.favcolor AS user_favcolor \nFROM user \nWHERE lower(user.email) LIKE lower(?)\n LIMIT ? OFFSET ?' (u'xxx#xxx.com', 1, 0)
Basically, I doubt that I'm creating user_datastore and security correctly, as I probably shouldn't be importing User and Role in that way -- but I'm not sure how to access them properly.
EDIT:
I added this final command, thanks to suggestion:
python db_manager.py db ugrade
But, now I get this error when I try to confirm a user registration via email:
(InvalidRequestError: Object '' is already attached to session '1' (this is '3')

The workflow with Flask-Migrate/Alembic is as follows:
db init
This you do once when you create the migration repository and never again.
db migrate
You run this to generate a migration script. The output of the command tells you where the migration script was created, and shows a summary of what was put in it. Your database has not been modified at this stage.
review the migration script
This is very important. Automatic migrations are not perfect, you have to review the generated script and make any corrections that are necessary.
db upgrade
This applies the migration to your database, effectively making the necessary schema changes.
You can now use your database. When you make more changes to your models return to Step 2 and repeat the cycle.
From your description you maybe missed step 4, the upgrade call.
As a side note, you have some duplication between your two scripts, you should try to consolidate them. Take a look at how people build Flask applications split across multiple modules or packages.