CODEWITHSUNDEEP
pythontkinter
gokul
gokul

Reputation: 109

Exception in Tkinter callback Traceback error.How to handle this

This is a small python program to add 2 numbers using tkinter gui.It runs fine if there is some input in the text field.How to handle the errors caused if the input is either blank or characters other than number.

from tkinter import *

root = Tk()


class addtwo:

    def evaluate(self, master, label, a, b):
        label.configure(text="The result is" + str(a+b))

    def __init__(self, master):
        frame = Frame(master, width=300, height=200)

        button1 = Button(master, text="Sum")
        input1 = Entry(master, text="Text1")
        input2 = Entry(master, text="Text2")
        label = Label(master, text="")



        button1.bind("<Button-1>", lambda event: self.evaluate(master, label,int(input1.get()),int(input2.get()) ))





        input1.pack()
        input2.pack()
        frame.focus()
        button1.pack()
        label.pack()
        frame.pack()


addtwo(root)
   root.mainloop()

Error:

Exception in Tkinter callback
Traceback (most recent call last):
  File "/usr/lib/python3.5/tkinter/__init__.py", line 1553, in __call__
    return self.func(*args)
  File "/home/temporary/PycharmProjects/practise/addtwo.py", line 21, in <lambda>
    button1.bind("<Button-1>", lambda event: self.evaluate(master, label,int(input1.get()),int(input2.get()) ))
ValueError: invalid literal for int() with base 10: ''

Upvotes: 0

Views: 2091

Answers (1)

furas
furas

Reputation: 142909

You can use try/except to catch error and display some message in Label instead of result.

import tkinter as tk

class AddTwo:

    def __init__(self, master):
        frame = tk.Frame(master, width=300, height=200)

        self.input1 = tk.Entry(master, text="Text1")
        self.input2 = tk.Entry(master, text="Text2")
        button1 = tk.Button(master, text="Sum", command=self.evaluate)
        self.label = tk.Label(master, text="")

        self.input1.pack()
        self.input2.pack()
        button1.pack()
        self.label.pack()
        frame.pack()
        frame.focus()

    def evaluate(self):
        a_str = self.input1.get()
        b_str = self.input2.get()
        try:
            a = int(a_str)
            b = int(b_str)
        except ValueError:
            self.label['text'] = "Wrong value(s) {} and/or {}".format(a_str, b_str)
            return

        self.label['text'] = "The result is {}".format(a+b)

# --- main ---

root = tk.Tk()
AddTwo(root)
root.mainloop()

Upvotes: 1

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