CTkEntry _textvariable_callback issue

[Lutheine]

Hi Tom, I'm experiencing alike issue right now, but the difference is that widget throwing exception error is CTkEntry. I'm doing dynamic UI and when trying to destroy widget, I want to empty out any text in textvariable stringVar stored, so I can reuse the same variable if widget is created again. After destroying a widget, textvariable can't be .set('') without error, while .set('%anything%') doesn't throw exceptions.

Code:

from customtkinter import CTk, CTkEntry, CTkComboBox
from tkinter import StringVar

root = CTk()

TEST = StringVar()

def clear():
    for c in root.winfo_children():
        c.destroy()

def load():
    test = CTkEntry(root, textvariable=TEST)
    test.pack()

TEST.set("") #no error
load()
TEST.set("") #no error
clear()
TEST.set("") #throws error, but still works, stringvar changes to ''
TEST.set("%") #no error

root.mainloop()

Error:

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Program Files\Python311\Lib\tkinter\__init__.py", line 1948, in __call__
    return self.func(*args)
           ^^^^^^^^^^^^^^^^
  File "C:\Program Files\Python311\Lib\site-packages\customtkinter\windows\widgets\ctk_entry.py", line 121, in _textvariable_callback
    self._activate_placeholder()
  File "C:\Program Files\Python311\Lib\site-packages\customtkinter\windows\widgets\ctk_entry.py", line 299, in _activate_placeholder
    if self._entry.get() == "" and self._placeholder_text is not None and (self._textvariable is None or self._textvariable == ""):
       ^^^^^^^^^^^^^^^^^
  File "C:\Program Files\Python311\Lib\tkinter\__init__.py", line 3099, in get
    return self.tk.call(self._w, 'get')
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
_tkinter.TclError: invalid command name ".!ctkentry.!entry"

Originally posted by @Lutheine in https://github.com/TomSchimansky/CustomTkinter/issues/468#issuecomment-1713529172

[its-ahad]

Use TEST.set(None) and update the load function as follow. def load(): if TEST.get() != 'None': test = CTkEntry(root, textvariable=TEST) test.pack() Hopefully this will resolve your issue

[Lutheine]

Hi Ahad, that doesn't solve the problem just because None is being treated like string 'None' and causes the variable to be 4 length while I need it to be 0, when variable is not in use. It's no different than assigning variable to any string, I currently workaround with ' ' instead of '' and then later use check if len(var.strip()) == 0.

Have a look:

TEST = StringVar()
TEST.set(None)
print(len(TEST.get()))      #result is 4, while should be 0 for my needs
print(type(Test.get()))     #results in class type of str
print(type(None))           #it's class type of NoneType