python中的属性错误。对象没有属性

Question

这段代码是一个更大的程序的一部分，该程序使用 google Sheets API 从云数据库中获取数据（不是真正相关，但一点上下文永远不会受到伤害！）

我在一个名为“oop.py”的 python 文件中有这段黑色代码

class SetupClassroom:

    def __init__(self, arraynumber='undefined', tkroot='undefined'):

        self.arraynumber = arraynumber

        self.tkroot = tkroot

    def setarraynumber(self, number):

        from GUI_Stage_3 import showclassroom

        self.arraynumber = number

        print ('set array number:', number)

        showclassroom()

    def settkroot(self, tkrootinput):

        self.tkroot = tkrootinput

self.tkroot 已被另一部分代码赋值。这一点有效，因为我已经测试过它正在被分配，但是，当我在另一个这样的文件中调用“self.tkroot”时

def showclassroom():

    from oop import SetupClassroom

    username = current_user.username

    classnumber = getnumberofuserclassrooms(username)

    if SetupClassroom.arraynumber > classnumber:

        errorwindow('you are not enrolled in that many classrooms!')

    else:

        classtoget = SetupClassroom.arraynumber

        print('classtoget:', classtoget)

        root = SetupClassroom.tkroot

        name_label = Label(root, text=classtoget)

        getclassroom(username, classtoget)

SetupClassroom = SetupClassroom

我收到这个错误

Exception in Tkinter callback

Traceback (most recent call last):

  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/tkinter/__init__.py", line 1705, in __call__

    return self.func(*args)

  File "/Users/jonathansalmon/PycharmProjects/Coursework_GUI/GUI_Stage2_better.py", line 176, in <lambda>

    l0 = ttk.Button(teacher_root, text=button0text, command=lambda: (SetupClassroom.setarraynumber(SetupClassroom, number=button0text), SetupClassroom.settkroot(SetupClassroom, 'teacher_root')))

  File "/Users/jonathansalmon/PycharmProjects/Coursework_GUI/oop.py", line 99, in setarraynumber

    showclassroom()

  File "/Users/jonathansalmon/PycharmProjects/Coursework_GUI/GUI_Stage_3.py", line 29, in showclassroom

    root = SetupClassroom.tkroot

AttributeError: type object 'SetupClassroom' has no attribute 'tkroot'

我尝试在 python 控制台中设置它并且它起作用了，所以我不知道问题是什么。如果有人可以提供帮助，将不胜感激 谢谢！约翰

Answer 1

您应该创建一个类的实例，它将在 中创建属性__init__，self.tkroot是实例的属性而不是类：setupClassroom = SetupClassroom()print(setupClassroom.tkroot)希望这会帮助你。