满足条件后如何让消息框出现？

Question

我正在尝试通过 Tkinter 创建登录屏幕，并且我希望消息框在用户输入正确的用户名和密码或未正确输入时显示消息。 当我运行程序并输入用户名和密码时，没有出现消息框。有没有办法解决这个问题？

from tkinter import *
from tkinter import messagebox

root = Tk()
root.geometry("300x270")
root.title("staff login")
root.resizable(False, False)
root.configure(background ="black")

label = Label(root, text = "staff log-in") 
frame_heading = Frame(root)
frame_heading.grid(row=0, column=0, columnspan=2, padx=25,pady=10)

frame_entry = Frame(root) 
frame_entry.grid(row=1, column=0, columnspan=2, padx=25, pady=10)

Label(frame_heading,text ="Staff log-in",
font =('Arial',16))\
                  .grid(row=0, column=0, padx=0, pady=5)

Label(frame_entry, text = "Username: ")\
                .grid(row=2, column=0, padx=10, pady=5)
label(frame_entry, text = "Password: ")\
                .grid(row=3, column=0, padx=10, pady=5)
    
def login():
    label.config (text = "log in")
    username = Entry(frame_entry, width = 15, bg = "white")
    username.grid(row=2, column=1, padx=5,pady=5)

    password = Entry(frame_entry, width = 15, bg = "white")
    password.grid(row=3, column=1, padx=5,pady=5)

loginbutton = Button(root, text="Login",width=7,
                     command=login)
loginbutton.grid(row=2, column=0, padx=0, pady=5)

def loginbutton():
    username = username_entry.get()
    password = password_entry.get()
    if (username == 'admin' and password == 'abcd1234'):
        messagebox.showinfo('info', 'Correct Login')
    else:
        messagebox.showinfo('info', 'Invalid Login')

root.mainloop()

Answer 1

您的代码没有运行，所以我不得不更改一些内容。您还拥有它，因此您必须按下登录按钮才能显示用户名和密码框。这就是我所拥有的，我相信你正在努力实现的目标。

from tkinter import *
from tkinter import messagebox

root = Tk()
root.geometry("300x270")
root.title("staff login")
root.resizable(False, False)
root.configure(background="black")

label = Label(root, text="staff log-in")
frame_heading = Frame(root)
frame_heading.grid(row=0, column=0, columnspan=2, padx=25, pady=10)

frame_entry = Frame(root)
frame_entry.grid(row=1, column=0, columnspan=2, padx=25, pady=10)

Label(frame_heading, text="Staff log-in",
      font=('Arial', 16)).grid(row=0, column=0, padx=0, pady=5)

Label(frame_entry, text="Username: ").grid(row=2, column=0, padx=10, pady=5)
Label(frame_entry, text="Password: ").grid(row=3, column=0, padx=10, pady=5)


# def login(): -- I commented this line because the username and password entries should automatically populate
            #  -- The way you were doing it before these did not populate until after you pressed login
label.config(text="log in")
username = Entry(frame_entry, width=15, bg="white")
username.grid(row=2, column=1, padx=5, pady=5)

password = Entry(frame_entry, width=15, bg="white")
password.grid(row=3, column=1, padx=5, pady=5)

# Added the lambda command to the login function you wrote, which was never called anywhere else in the script.
loginbutton = Button(root, text="Login", width=7, command=lambda : loginbutton(username, password))
loginbutton.grid(row=2, column=0, padx=0, pady=5)


def loginbutton(username_entry, password_entry):
    username = username_entry.get()
    password = password_entry.get()
    if (username == 'admin' and password == 'abcd1234'):
        messagebox.showinfo('info', 'Correct Login')
    else:
        messagebox.showinfo('info', 'Invalid Login')


root.mainloop()

Answer 2

问题

您的代码中存在多个问题，主要围绕提供错误的变量名称。一些主要问题是：

• 在 loginbutton 中，您尝试访问 username_entry 和 password_entry 变量，但在构建您所做的小部件时 username = Entry(...) 和 password = Entry(...)
• 单击“登录”按钮时将调用的command 定义为login，这与创建用户名和密码条目以及登录按钮的函数相同

解决方案

我相信你想要这样的东西：

from tkinter import *
from tkinter import messagebox

def checkLogin():
    username = username_entry.get()
    password = password_entry.get()
    if (username == 'admin' and password == 'abcd1234'):
        messagebox.showinfo('info', 'Correct Login')
    else:
        messagebox.showinfo('info', 'Invalid Login')

root = Tk()
root.geometry("300x270")
root.title("staff login")
root.resizable(False, False)
root.configure(background ="black")

label = Label(root, text = "staff log-in") 
frame_heading = Frame(root)
frame_heading.grid(row=0, column=0, columnspan=2, padx=25,pady=10)

frame_entry = Frame(root) 
frame_entry.grid(row=1, column=0, columnspan=2, padx=25, pady=10)

Label(frame_heading,text ="Staff log-in",
font =('Arial',16))\
                  .grid(row=0, column=0, padx=0, pady=5)

Label(frame_entry, text = "Username: ")\
                .grid(row=2, column=0, padx=10, pady=5)
Label(frame_entry, text = "Password: ")\
                .grid(row=3, column=0, padx=10, pady=5)

label.config (text = "log in")
username_entry = Entry(frame_entry, width = 15, bg = "white")
username_entry.grid(row=2, column=1, padx=5,pady=5)

password_entry = Entry(frame_entry, width = 15, bg = "white")
password_entry.grid(row=3, column=1, padx=5,pady=5)

loginbutton = Button(root, text="Login",width=7,
                     command=checkLogin)
loginbutton.grid(row=2, column=0, padx=0, pady=5)

root.mainloop()

重点是在创建登录按钮时，指定command 到checkLogin，这是您在用户单击登录按钮后执行任何检查的函数。