我無法使用 .get() 獲取我的 Tkinter Checkbutton 變量值

Question

所以我一直在做一個項目，最近遇到了我的復選按鈕的問題。 每當我嘗試執行variablenname.get() ，它都不會起作用，因為它說int value has no attribute get() 。 我也使用了variablename = IntVar() ，我想要做的是使 if 語句依賴於 checkbutton 的值。

        var = IntVar()
        BTR = Tk()
        Discounts = Checkbutton(BTR, text="Discount (Students, Under 18s, 65+ and Disability Badge Holders)", font = ("times", 30), bg="#252538", fg = "#99FFFF", variable = var)
        Discounts.place(x=120, y=300)
        PriceTag=Label(BTR, text =("£", Cost), font = ("times", 50), fg = "White", bg = "#252538")
        PriceTag.place(x=1000, y= 450)
        val=Label(BTR, text = Tickets, font = ("times", 22), height = 5, width = 15, bg= "White")
        val.place(x=175, y=550)
        add=Button(BTR, text = "+", font = ("times", 22), height = 5, width = 10, bg = "#B266FF", command = lambda: UpdateAdd(val, BTR, PriceTag, BusTicketPrice, price, var))
        add.place(x=420, y=550)

    def UpdateAdd(val, BTR, PriceTag, BusTicketPrice, price, var):
      var = var.get()
      Tickets = Tickets + 1 
      val.destroy()
      val = Label(BTR, text = Tickets, font = ("times", 22), height = 5, width = 15, bg= "White")
      val.place(x=175, y=550)
      PriceTag.destroy()
      if price == "Peak" and var == 0 :
          BusTicketPrice=BusTicketPrice*1.25
      elif var == 1 and price == "Peak":
          BusTicketPrice=BusTicketPrice
      elif var == 1 and price == "Off-Peak":
          BusTicketPrice=BusTicketPrice*0.75
      elif price == "Off-Peak" and var == 0):
          BusTicketPrice=BusTicketPrice
      Cost = BusTicketPrice * Tickets
      Cost = round(Cost, 3)
      PriceTag=Label(BTR, text =("£", str(Cost), "0"), font = ("times", 50), fg = "White", bg = "#252538")
      PriceTag.place(x=1000, y= 450)

Answer 1

這段代碼有幾個問題。 首先，在創建根窗口並使用Tk()調用啟動 Tcl 解釋器之前，您不應嘗試創建任何 Tkinter 對象，包括小部件和 IntVars。 我很驚訝您的代碼沒有打印類似的錯誤消息

AttributeError: 'NoneType' object has no attribute '_root'

因為你在BTR = Tk()之前有var = IntVar() BTR = Tk() 。 我沒有嘗試運行您發布的代碼，因為它不是MCVE 。

您的錯誤的主要原因是在UpdateAdd您在函數開頭附近執行var = var.get() （它從var獲取整數值，然后將該整數對象綁定到名稱var ），但再進一步下來你有var.get() ，這將不起作用，因為現在var指的是整數對象，而不是它最初綁定到的IntVar 。

這是一個最小的程序，它演示了將 IntVar 與 Checkbutton 一起使用確實按預期工作。

import tkinter as tk

BTR = tk.Tk()
var = tk.IntVar()

title = tk.Label(BTR, text="Purchase Bus or Tram Tickets")
title.pack()

discounts = tk.Checkbutton(BTR, text="Discount", variable=var)
discounts.pack()

test = tk.Button(BTR, text="test", command=lambda: print(var.get()))
test.pack()

BTR.mainloop()

當您按下“測試”按鈕時，Checkbutton 的當前狀態將打印到控制台。