无法使用 SQLAchemy 在数据库中创建表

Question

i have created app.py and tables.py which are the main app and a file used to define the tables of a database [database.db] respectively. I cannot create tables in the database.db, what could be the problem? Code for both is given below

#app.py

from flask import Flask, render_template, request, session, redirect
from tables import db
from flask_session import Session
app = Flask(__name__)
app.config["SESSION_PERMANENT"] = False
app.config["SESSION_TYPE"] = "filesystem"
Session(app)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///database.db'
db.init_app(app)

@app.before_first_request
def create_tables():
db.create_all()
 @app.route("/")
def home():
return render_template("register.html")

#tables.py

from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy()
class users (db.Model):
    users_key = db.Column(db.Integer, primary_key=True, autoincrement=True)
    username = db.Column(db.String(21), nullable=False)
    email = db.Column(db.String(31), nullable=False, unique=True)
    password = db.Column(db.String(61), nullable=False)

i expected to get tables in the database.db file which is located in the same directory as the app.py file. i could not add any tables though.

Answer 1

You have to create database context and initialize it.

with app.app_context():
    db.create_all()

Also make sure to import the Flask module from the flask package and SQLAlchemy from the flask_sqlalchemy package in tables.py.

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///database.db'
db = SQLAlchemy(app)