python - 类型错误 : 'NoneType' object has no attribute '__getitem__' tkinter error

Question

我在这里遇到的问题是，每当我尝试将数据输入我的用户名输入框 (self.KUEntry.get()) 并在我的查询中运行该输入框时，它返回 none 并抛出问题中列出的错误。

该函数应该检查注册用户存储的 salt 和哈希值，并将其与他们在输入框中输入的密码进行比较。

def login_verification(self):

    username = self.KUEntry.get()
    print username

    cursor1.execute = ("SELECT salt FROM User WHERE username = (%s)", username)
    salty = cursor1.fetchone() [0]
    print salty

    cursor2.execute = ("SELECT PashHash FROM User WHERE username = %s", (username))
    hashy = cursor2.fetchone() [0]
    print hashy

    test = hashlib.sha512(username + salty).hexdigest
    print test

    if test == hashy:
        self.mainscreen
    else:
        print "incorrect password"

Answer 1

像这样放置我的代码可以修复回溯错误，但它不会返回预期的结果。而不是我的 cursor1.fetchone 和 cursor2.fetchone 方法返回查询结果，它们返回“无”。

def login_verification(self):

    username = self.KUEntry.get()
    print username

    cursor1.execute = ("SELECT salt FROM User WHERE username = %s", str(username))
    salty = str(cursor1.fetchone())
    print salty

    cursor2.execute = ("SELECT PashHash FROM User WHERE username = %s", str(username))
    hashy = str(cursor2.fetchone())
    print hashy

    test = hashlib.sha512(username + str(salty)).hexdigest
    print test

    if test == hashy:
        self.mainscreen
    else:
        print "incorrect password"