tk.PhotoImage is not loading image in another instance of Tk()

Question

I am building an application which have a main menu and some side menus/forms. Those forms are created in separate files as following:-

from tkinter import *
import tkinter as tk


class side_test():
    def __init__(self):
        self.window = Tk()
        self.window.geometry("500x500+100+100")
        self.my_image = tk.PhotoImage(file='req_hv.png')
        self.my_button = Button(self.window, image=self.my_image)
        self.my_button.image = self.my_image
        self.my_button.pack()

    def run(self):
        self.window.mainloop()

a main menu is created in a separate file as:-

from tkinter import *
import tkinter as tk
from side_test import side_test
class main_test():
    def __init__(self):
        self.window = Tk()
        self.window.geometry("300x300")
        self.main_image = tk.PhotoImage( file='req.png')
        self.my_button = Button(window, image=self.main_image, command=self.side_from)
        self.my_button.image = self.main_image
        self.my_button.pack()

    def side_form(self):
        my_obj = side_test()
        my_obj.run()

    def run(self):
        self.window.mainloop()
if __name__ == '__main__':
    obj = main_test()
    obj.run()

as u can see I am calling side_test class. upon execution it through following error:-

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Program Files\Python310\lib\tkinter\__init__.py", line 1921, in __call__return self.func(*args)
  File "f:\Docs\OneDrive\Python Projects\test\main_test.py", line 18, in side_form
    my_obj = side_test()
  File "f:\Docs\OneDrive\Python Projects\test\side_test.py", line 11, in __init__
    self.my_button = Button(self.window, image=self.my_image)
  File "C:\Program Files\Python310\lib\tkinter\__init__.py", line 2679, in __init__
    Widget.__init__(self, master, 'button', cnf, kw)
  File "C:\Program Files\Python310\lib\tkinter\__init__.py", line 2601, in __init__
    self.tk.call(
_tkinter.TclError: image "pyimage2" doesn't exist

but if i run side_test file separately, it run correctly. I dont know why tcl do not locate picture file while called from another file.

Answer 1

For more than one instance of Tk(), master option shall be used e.g.

tk.PhotoImage(file='example.png', master=self)

Answer 2

Don't use wildcard from tkinter import * for both modules.

Snippet modified the code to improve readability:

side_test.py.

side_test

import tkinter as tk

class side_test():
    def __init__(self):
        self.window = Tk()
        self.window.geometry("500x500+100+100")
        self.my_image = tk.PhotoImage(file='p1.png')
        self.my_button = Button(self.window, image=self.my_image)
        self.my_button.image = self.my_image
        self.my_button.pack()
        self.window.mainloop()

def run():
    side_test()

main.py.

import tkinter as tk
from side_test import side_test

class main_test():
    def __init__(self):
        self.window = Tk()
        self.window.geometry("300x300")
        self.main_image = tk.PhotoImage( file='p2.png')
        self.my_button = tk.Button(self.window, image=self.main_image, command=self.side_from)
        self.my_button.image = self.main_image
        self.my_button.pack()
        self.window.mainloop()

def side_form():
    side_test()
    my_obj.run()

def run():
    side_form()
         
if __name__ == '__main__':
    run()

Screenshot: