[英]How to assign a variable to tkinter's entry box using a function
Here's an example of code before I explain my issue. 在我解释问题之前,这是一个代码示例。
from tkinter import *
from tkinter import messagebox
class Add:
def __init__(self, master):
self.frame = Frame(master)
self.frame.grid()
self.entry_1 = Entry(self.frame)
self.entry_1.grid(row=0, column=0)
self.entry_2 = Entry(self.frame)
self.entry_2.grid(row=1, column=0)
self.button = Button(self.frame, text='Submit', command=self.submit)
self.button.grid(row=0, column=1)
def submit(self):
# Checks if both entries are digits.
if self.entry_1.get().isdigit() is False:
messagebox.showerror('Error', 'Invalid Character(s).')
elif self.entry_2.get().isdigit() is False:
messagebox.showerror('Error', 'Invalid Character(s).')
add_entry_1_and_2 = int(self.entry_1.get()) + int(self.entry_2.get())
print(add_entry_1_and_2)
root = Tk()
Add(root)
root.mainloop()
This code works great as long as I have a number assigned to both entry boxes, but if I leave one of the boxes empty and press the submit button it raises this error. 只要我为两个输入框分配了一个数字,此代码就可以很好地工作,但是如果我将其中一个输入框留空并按提交按钮,则会引发此错误。
ValueError: invalid literal for int() with base 10: ''
What I want is if one of the boxes is left empty I would like to assign that empty box to the value of 0. How could I achieve this? 我想要的是如果其中一个框保留为空,我想将该空框分配为0值。如何实现呢?
You could set a default value zero in each of the entry fields, and reset this value upon submitting. 您可以在每个输入字段中将默认值设置为零,并在提交时重置此值。
Then you could check the validity of an entry value in a try-except block, and proceed to adding the values only if they conform, otherwise, raise an exception that triggers the Error popup. 然后,您可以检查try-except块中条目值的有效性,并仅在它们符合时才继续添加值;否则,引发触发Error弹出窗口的异常。
something like this, maybe? 这样的事,也许吗?
from tkinter import *
from tkinter import messagebox
class Add:
def __init__(self, master):
self.frame = Frame(master)
self.frame.grid()
self.default_value = '0'
self.entry_1 = Entry(self.frame)
self.entry_1.grid(row=0, column=0)
self.entry_2 = Entry(self.frame)
self.entry_2.grid(row=1, column=0)
self.button = Button(self.frame, text='Submit', command=self.submit)
self.button.grid(row=0, column=1)
self.reset_entry_defaults()
def reset_entry_defaults(self):
self.entry_1.delete(0,END)
self.entry_2.delete(0,END)
self.entry_1.insert(0, self.default_value)
self.entry_2.insert(0, self.default_value)
def submit(self):
try:
e1 = int(self.entry_1.get()) # <-- you may prefer to convert to float
e2 = int(self.entry_2.get()) # <-- you may prefer to convert to float
except ValueError:
messagebox.showerror('Error', 'Invalid Character(s).')
else:
add_entry_1_and_2 = e1 + e2
print(add_entry_1_and_2)
self.reset_entry_defaults()
root = Tk()
Add(root)
root.mainloop()
Optionally, you could have your class Add
inherit from tk.Frame
(be a tk.Frame
), and do something like this: (可选)您可以让
class Add
从tk.Frame
(是tk.Frame
)继承,并执行以下操作:
import tkinter as tk # <-- avoid star imports
from tkinter import messagebox
class Add(tk.Frame): # <-- inherit from tk.Frame
def __init__(self, master):
self.master = master
super().__init__(self.master) # <-- call the parent class
self.default_value = '0'
self.entry_1 = tk.Entry(self)
self.entry_1.grid(row=0, column=0)
self.entry_2 = tk.Entry(self)
self.entry_2.grid(row=1, column=0)
self.button = tk.Button(self, text='Submit', command=self.submit)
self.button.grid(row=0, column=1)
self.reset_entry_defaults()
def reset_entry_defaults(self):
self.entry_1.delete(0, tk.END)
self.entry_2.delete(0, tk.END)
self.entry_1.insert(0, self.default_value)
self.entry_2.insert(0, self.default_value)
def submit(self):
try:
e1 = int(self.entry_1.get())
e2 = int(self.entry_2.get())
except ValueError:
tk.messagebox.showerror('Error', 'Invalid Character(s).')
else:
add_entry_1_and_2 = e1 + e2
print(add_entry_1_and_2)
self.reset_entry_defaults()
root = tk.Tk()
Add(root).grid() # <-- call the tk geometry manager to place your frame in root
root.mainloop()
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