When I enter a date in an Entry I would like for it to have slashes between dates like so:
"01/23/4567".

I found this code and although it works while also validating that the entry are numbers, there is one problem. It doesn't let me clear the entry input. I tried the .delete(0, END) method with a button but doesn't seem to work at all and if you press backspace, the first character, "0" in this example "01/23/4567", doesn't get deleted, it stays there.

import tkinter as tk, re

class DateEntry(tk.Entry):
    def __init__(self, master, **kwargs):
        tk.Entry.__init__(self, master, **kwargs)
        vcmd = self.register(self.validate)
        
        self.bind('<Key>', self.format)
        self.configure(validate="all", validatecommand=(vcmd, '%P'))
        
        self.valid = re.compile('^\d{0,2}(\\\\\d{0,2}(\\\\\d{0,4})?)?$', re.I)
             
    def validate(self, text):
        if ''.join(text.split('\\')).isnumeric():
            return not self.valid.match(text) is None
        return False
    
    def format(self, event):
        if event.keysym != 'BackSpace':
            i = self.index('insert')
            if i in [2, 5]:
                if self.get()[i:i 1] != '\\':
                    self.insert(i, '\\')
        

class Main(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)
        
        DateEntry(self, width=10).grid(row=0, column=0)
        

if __name__ == "__main__":
    root = Main()
    root.geometry('800x600')
    root.title("Date Entry Example")
    root.mainloop()

CodePudding user response：

If you need to be able to clear the widget, your validation function needs to account for the special case of an empty value.

def validate(self, text):
    if text.strip() == "":
        # allow a completely empty entry widget
        return True
    if text ''.join(text.split('\\')).isnumeric():
        return not self.valid.match(text) is None
    return False