Flask-SQLAlchemy выдает пустой список db.session.query(Class).all(). Как исправить?

Ребята, гугл не помогает. Элементарное. Есть база данных. Подключаем ее. Хотим извлечь все элементы. А выдает пустой список. Почему так происходит? Как исправить?

from flask import Flask, jsonify, render_template
from flask_sqlalchemy import SQLAlchemy
import random

app = Flask(__name__)

##Connect to Database
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///cafes.db'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
db = SQLAlchemy(app)
db.init_app(app)

##Cafe TABLE Configuration
class Cafe(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(250), unique=True, nullable=False)
    map_url = db.Column(db.String(500), nullable=False)
    img_url = db.Column(db.String(500), nullable=False)
    location = db.Column(db.String(250), nullable=False)
    seats = db.Column(db.String(250), nullable=False)
    has_toilet = db.Column(db.Boolean, nullable=False)
    has_wifi = db.Column(db.Boolean, nullable=False)
    has_sockets = db.Column(db.Boolean, nullable=False)
    can_take_calls = db.Column(db.Boolean, nullable=False)
    coffee_price = db.Column(db.String(250), nullable=True)

    def to_dict(self):
        # Method 1.
        dictionary = {}
        # Loop through each column in the data record
        for column in self.__table__.columns:
            # Create a new dictionary entry;
            # where the key is the name of the column
            # and the value is the value of the column
            dictionary[column.name] = getattr(self, column.name)
        return dictionary

        # Method 2. Altenatively use Dictionary Comprehension to do the same thing.
        # return {column.name: getattr(self, column.name) for column in self.__table__.columns}
   

@app.route("/all")
def get_all_cafes():
    cafes = db.session.query(Cafe).all()
    print(cafes)
    # This uses a List Comprehension but you could also split it into 3 lines.
    return jsonify(cafes=[cafe.to_dict() for cafe in cafes])



if __name__ == '__main__':
    app.run(debug=True)