Python 登录后切换帧

输入正确的登录名和密码后，我正在尝试切换到新的框架。 不幸的是，一旦我输入了所有的细节，什么都不会发生。 不知道如何强制它打开新的框架。 我同意在没有登录位的框架之间切换，但不知道如何将登录功能附加到框架上

 from tkinter import *
import tkinter.messagebox as tm
import tkinter as tk

class SampleApp(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)
        self._frame = None
        self.switch_frame(LoginFrame)

    def switch_frame(self, frame_class):
        """Destroys current frame and replaces it with a new one."""
        new_frame = frame_class(self)
        if self._frame is not None:
            self._frame.destroy()
        self._frame = new_frame
        self._frame.pack()


class LoginFrame(tk.Frame):
    def __init__(self, parent):
        super().__init__(parent)


        self.label_username = Label(self, text="Username")
        self.label_password = Label(self, text="Password")

        self.entry_username = Entry(self)
        self.entry_password = Entry(self, show="*")

        self.label_username.grid(row=0, sticky=E)
        self.label_password.grid(row=1, sticky=E)
        self.entry_username.grid(row=0, column=1)
        self.entry_password.grid(row=1, column=1)



        self.logbtn = Button(self, text="Login", command=self._login_btn_clicked)
        self.logbtn.grid(columnspan=2)



    def _login_btn_clicked(self):
        # print("Clicked")
        username = self.entry_username.get()
        password = self.entry_password.get()

        # print(username, password)

        if username == "abc" and password == "123":
            lambda: parent.switch_frame(PageOne)
        else:
            tm.showerror("Login error", "Incorrect username or password")

class PageOne(tk.Frame):
    def __init__(self, parent):
        tk.Frame.__init__(self, parent)
        tk.Label(self, text="This is page one").pack(side="top", fill="x", pady=10)
        tk.Button(self, text="Return to login page",
                  command=lambda: parent.switch_frame(LoginFrame)).pack()

if __name__ == "__main__":
    app = SampleApp()
    app.mainloop()

---

有几个问题。根本问题在于这两行代码：

if username == "abc" and password == "123":
    lambda: parent.switch_frame(PageOne)

这不会导致页面切换。相反，它只是创建一个匿名函数，该函数将导致页面切换。您不希望创建函数，而是希望实际切换帧。在这种情况下，应如下所示：

if username == "abc" and password == "123":
    parent.switch_frame(PageOne)

但是，未定义父级。您需要在

\uuuu init\uuuu

方法中保存

父项

，以便在此处访问它

class LoginFrame(tk.Frame):
    def __init__(self, parent):
        super().__init__(parent)
        self.parent = parent
        ...

    def _login_btn_clicked(self):
        ...
        if username == "abc" and password == "123":
            self.parent.switch_frame(PageOne)

---

工作如梦感谢大家的帮助，下面粘贴了固定代码

from tkinter import *
import tkinter.messagebox as tm
import tkinter as tk

class SampleApp(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)
        self._frame = None
        self.switch_frame(LoginFrame)

    def switch_frame(self, frame_class):
        """Destroys current frame and replaces it with a new one."""
        new_frame = frame_class(self)
        if self._frame is not None:
            self._frame.destroy()
        self._frame = new_frame
        self._frame.pack()


class LoginFrame(tk.Frame):
    def __init__(self, parent):
        super().__init__(parent)
        self.parent = parent


        self.label_username = Label(self, text="Username")
        self.label_password = Label(self, text="Password")

        self.entry_username = Entry(self)
        self.entry_password = Entry(self, show="*")

        self.label_username.grid(row=0, sticky=E)
        self.label_password.grid(row=1, sticky=E)
        self.entry_username.grid(row=0, column=1)
        self.entry_password.grid(row=1, column=1)



        self.logbtn = Button(self, text="Login", command=self._login_btn_clicked)
        self.logbtn.grid(columnspan=2)



    def _login_btn_clicked(self):
        # print("Clicked")
        username = self.entry_username.get()
        password = self.entry_password.get()

        # print(username, password)

        if username == "abc" and password == "123":
            self.parent.switch_frame(PageOne)
        else:
            tm.showerror("Login error", "Incorrect username or password")

class PageOne(tk.Frame):
    def __init__(self, parent):
        tk.Frame.__init__(self, parent)
        tk.Label(self, text="This is page one").pack(side="top", fill="x", pady=10)
        tk.Button(self, text="Return to login page",
                  command=lambda: parent.switch_frame(LoginFrame)).pack()

if __name__ == "__main__":
    app = SampleApp()
    app.mainloop()

---

将

lambda:parent.switch\u frame（PageOne）

替换为

parent.switch\u frame（PageOne）

刚才尝试的内容是：第51行，在“登录”中单击了“父项”。switch\u frame（PageOne）name错误：未定义名称“父项”错误：未定义名称“父项”“：您已将

parent

设置为类方法。在

\uuuuu init\uuuuuuuuuu

do

self.parent=parent

中，在

def\u login\u btn\u中单击（…

do

self.parent.switch（…