使用StringVar更新Tkinter标签

Question

我正在尝试为超简单的自动售货机编写GUI，但是在使用单选按钮进行选择后，我无法更新标签。 相反，当按下单选按钮时，无论选择什么，它都会将标签设置为默认值。

这是我的代码：

from tkinter import *
import tkinter as tk


#Native Functions
def f_Update():

global chocchoice
global price

c = chocchoice
    if c == "m":
        price = 60
        chocprice.set(price)
        chocname.set("You have chosen - Mars")
    if c == "t":
        price = 70
        chocprice.set(price)
        chocname.set("You have chosen - Twix")
    if c == "mw":
        price = 65
        chocprice.set(price)
        chocname.set("You have chosen - Milky Way")
    if c == "s":
        price == 80
        chocprice.set(price)
        chocname.set("You have chosen - Snickers")



root =tk.Tk()


#Let's declare some  variables!
chocchoice = "s"
price = 0
chocprice = StringVar()
chocname = StringVar()
summary = StringVar()


#Actual Code


frame = tk.Frame(root,
             height = 300,
             width = 800)

frame.pack()

L1 = tk.Label(root,
          text = "Please select a chocolate bar:",
          bg = "white")
L1.place(x=10, y=10)

Radiobutton(root,
            text="Mars",
            padx = 10,
            variable = chocchoice,
            value = "m",
            command = f_Update).place(x=10,y=40)
Radiobutton(root,
            text="Twix",
            variable = chocchoice,
            value = "t",
            command = f_Update).place(x=10, y=70)
Radiobutton(root,
            text="Milky Way",
            variable = chocchoice,
            value = "mw",
            command = f_Update).place(x=10, y=100)
Radiobutton(root,
            text="Snickers",
            variable = chocchoice,
            value = "s",
            command = f_Update).place(x=10, y=130)

L2 = tk.Label(root,
              textvariable = chocname ,
              bg = "white")
L2.place(x=350,y=10)

L3 = tk.Label(root,
              textvariable = chocprice,
              bg = "white")
L3.place(x=350,y=40)

我浏览了该网站，但没有找到能解决此问题的任何东西。

Answer 1

chocchoice必须是StringVar() ，而不是常规变量，因为所有variable=和textvariable=期望StringVar() ， IntVar()等。

chocchoice = StringVar(value="s")

然后您需要使用.get()

c = chocchoice.get()

---

顺便说一句：因为您不必使用=来为chocchoice分配新值， chocchoice您不必在函数中使用global chocchoice 。

---

编辑：较短的版本

import tkinter as tk

# --- functions ---

def update():

    c = choc_choice.get()

    if c in products:
        price, name = products[c]
        choc_price.set(price)
        choc_name.set(name)

# --- data ---

products = { # key: [price, name],
    "m": [60, "Mars"],
    "t": [70, "Twix"],
    "mw": [65, "Milky Way"], 
    "s": [80, "Snickers"],
}    

# --- main ---

root = tk.Tk()

# variables (have to be after tk.Tk())

choc_choice = tk.StringVar()
choc_name = tk.StringVar(value="- none -")
choc_price = tk.IntVar()
summary = tk.IntVar()

# left side

left_frame = tk.Frame(root)
left_frame.grid(row=0, column=0, padx=5)

tk.Label(left_frame, text="Please select a chocolate bar:").pack()

for key, val in products.items():
    price, name = val
    tk.Radiobutton(left_frame, text=name, value=key, anchor='w',
            variable=choc_choice, command=update).pack(fill='x')

# right side

right_frame = tk.Frame(root)
right_frame.grid(row=0, column=1, sticky='n', padx=5)

tk.Label(right_frame, text="You have chosen:").pack()
tk.Label(right_frame, textvariable=choc_name).pack()
tk.Label(right_frame, textvariable=choc_price).pack()

# start

root.mainloop()