相关疑难解决方法(0)

我正在尝试做一个像这样的简单连接查询，

SELECT food._id, food.food_name, food_categories.food_categories FROM food JOIN food_categories ON food.food_category_id = food_categories._id

但不断收到错误。这是我的课程设置方式。

class Food_Categories(db.Model):
    __tablename__ = 'food_categories'
    _id = db.Column(db.Integer, primary_key=True)
    food_categories = db.Column(db.String(30))

class Food(db.Model):
    __tablename__ = 'food'
    _id = db.Column(db.Integer, primary_key=True)
    food_name = db.Column(db.String(40))
    food_category_id = db.Column(db.Integer, ForeignKey(Food_Categories._id))
    food_category = relationship("Food_Categories")

我的查询函数看起来像这样。

@app.route('/foodlist')
def foodlist():
    if request.method == 'GET':
        results = Food.query.join(Food_Categories.food_categories).all()

    json_results = []
    for result in results:
        d = {'_id': result._id,
         'food': result.food_name,
         'food_category': result.food_categories}
    json_results.append(d)

    return jsonify(user=json_results)

我正在使用烧瓶。当我调用路线时，我收到此错误。

AttributeError: 'ColumnProperty' object has no …