Question

当我尝试在Flask视图中从数据库中删除项目时，会显示以下错误

UnboundLocalError: local variable 'restaurantToDelete' referenced before assignment

@app.route('/restaurant/<int:restaurant_id>/delete',methods=['GET','POST'])
def deleteRestaurant(restaurant_id):
    if request.method=='POST':
        restaurantToDelete=session.query(Restaurant).filter_by(id=restaurant_id).one()
        session.delete(restaurantToDelete)
        session.commit()
        return redirect(url_for('showRestaurants'))
    else:
        return render_template('deleterestaurant.html',restaurant=restaurantToDelete)

Answer 1

看看其他的，当时没有定义restaurantToDelete，你的代码应该像

@app.route('/restaurant/<int:restaurant_id>/delete',methods=['GET','POST'])
def deleteRestaurant(restaurant_id):
    restaurantToDelete=session.query(Restaurant).filter_by(id=restaurant_id).one()

    if request.method=='POST':
        session.delete(restaurantToDelete)
        session.commit()
        return redirect(url_for('showRestaurants'))
    else:
        return render_template('deleterestaurant.html',restaurant=restaurantToDelete)

Answer 2

您在restaurantToDelete - 块中定义变量if，然后尝试在else - 块中使用它。如果request.method不是POST，则该变量不存在，因为您的代码未进入if - 块。您可以通过在检查请求类型之前获取餐馆来解决此问题：

@app.route('/restaurant/<int:restaurant_id>/delete',methods=['GET','POST'])
def deleteRestaurant(restaurant_id):
    restaurantToDelete=session.query(Restaurant).filter_by(id=restaurant_id).one()
    if request.method=='POST':
        session.delete(restaurantToDelete)
        session.commit()
        return redirect(url_for('showRestaurants'))
    else:
        return render_template('deleterestaurant.html',restaurant=restaurantToDelete)

UnboundLocalError：在分配Flask app之前引用的局部变量'restaurantToDelete'

2 个答案: