Builtins.AttributeError：'NoneType'對象沒有屬性'check_password'

Question

這是我的aap.py文件。如果我提供未注冊的電子郵件和密碼，那么他們也可以進入/ login頁面。 此行引發錯誤“如果user.check_password（form.password.data）並且user不是None：”將不勝感激。

@app.route('/login', methods=['GET', 'POST'])
def login():
    form = LoginForm()
    if form.validate_on_submit():

        user = User.query.filter_by(email=form.email.data).first()

        if user.check_password(form.password.data) and user is not None:

            login_user(user)
            flash('Logged in successfully.')

            # If a user was trying to visit a page that requires a login
            # flask saves that URL as 'next'.
            next = request.args.get('next')

            # Checking if that next exists, otherwise we'll go to
            # the welcome page.
            if next == None or not next[0] == '/':
                next = url_for('welcome_user')

            return redirect(next)
    return render_template("login.html", form=form)    enter code here

Answer 1

Python編譯器從左向右移動，這意味着在僅使用and運算符檢查多個條件時，Python編譯器首先檢查第一個條件，如果為true，則移至第二個條件，以此類推。條件。

結果，如果將給定的行更改為如下所示，則代碼將按預期開始工作：

if user is not None and user.check_password(form.password.data):