如何为我的 tkinter 程序编写错误代码

Question

我有这个程序，它从用户那里获取一些输入并将其保存在 CSV 文件中。

现在我想制作一个错误代码，这样每当用户的消息超过 140 个字符时，它就会告诉他们最大字符数是 140。我该如何编程呢？

import tkinter
import csv
import random
from tkinter import *
import datetime
from tkinter import messagebox

window = tkinter.Tk()
window.geometry("1920x1080")

def on_click():
    messagebox.showerror("Error", 'Error: Het bericht mag maximaal 140 tekens bevatten')

label = Label(window, text="Click this button to show the message",
font=('Calibri 15 bold'))
label.pack(pady=20)

b = Button(window, text='Click me', command=on_click)
b.pack(pady=20)

def get_data():
    global button
    Message_data = Message.get()
    Name_data = Name.get()
    vandaag = datetime.datetime.today()
    s = vandaag.strftime("%a %d %b %Y %H:%M")
stations = ['Arnhem', 'Almere', 'Amersfoort', 'Almelo', 'Alkmaar', 'Apeldoorn', 'Assen', 'Amsterdam',          'Boxtel',
            'Breda', 'Dordrecht', 'Delft', 'Deventer', 'Enschede', 'Gouda', 'Groningen', 'Den Haag', 'Hengelo',
            'Haarlem', 'Helmond', 'Hoorn', 'Heerlen', 'Den Bosch', 'Hilversum', 'Leiden', 'Lelystad', 'Leeuwarden',
            'Maastricht', 'Nijmegen', 'Oss', 'Roermond', 'Roosendaal', 'Sittard', 'Tilburg', 'Utrecht', 'Venlo',
            'Vlissingen', 'Zaandam', 'Zwolle', 'Zutphen']
    station = random.choice(stations)
    with open('file.csv', 'a') as csvfile:
        w = csv.writer(csvfile, quoting=csv.QUOTE_ALL)
        #w.writerow([Message_data + ", " + Date_data + ", " + Name_data + ", " + station])
        if Name_data == '':
            w.writerow([Message_data + ", " + s + ", " + 'anoniem' + ", " + station])
        else:
            w.writerow([Message_data + ", " + s + ", " + Name_data + ", " + station])

Message_Text = tkinter.Label(window, text="Vul hier een bericht in", font=("Calibri", 20),bg="#a9a9a9",  fg="#ffffff")
Message = tkinter.Entry(window, font=("Calibri", 20),width=45, bg="#ffffff", fg="black")
Name_label = tkinter.Label(window, text="Vul hier je naam in", font=("Calibri", 20), fg="#ffffff")
Name = tkinter.Entry(window, font=("Calibri", 20), bg="#ffffff", fg="black")
button = tkinter.Button(window, text="Submit", width =20,height=5, font=("Calibri", 20),  command=get_data, bg="#a9a9a9", fg="#ffffff")


Message_Text.pack()
Message.pack()
Name_label.pack()
Name.pack()
button.pack()
window.mainloop()
#root.mainloop()

我尝试使用len() function 来确定Message_Data是否超过 140 个字符，然后以不同的方式对提交按钮进行编程以调用 function on_click ，但不幸的是这没有用。

Answer 1

试试吧：

def get_data():
    global button
    Message_data = Message.get()
    if len(Message_data) > 140:
        messagebox.showerror("Error", 'Error: Het bericht mag maximaal 140 tekens bevatten')
        return