Changing a Tkinter frame from a different frame - python-3.x

Question

I am making a project in Tkinter where I gather some information in one frame (let's call it Frame One) and, based on that information, I want to change the layout of a different frame (let's call it Frame Two).
The code I'm attaching is a bare-bones version of what I want to achieve (my project is about 630 lines long).
The problem I ran into was how to access the frame, which is a class. Googling I came across Bryan Oakley's response on https://stackoverflow.com/questions/48731097/calling-functions-from-a-tkinter-frame-to-another#= , but when I tried to replicate it, I got an error.
EDIT: the following modification made it work, so it currently appends "testing" to testText when the button on PageTwo is clicked.
from tkinter import *
from tkinter import ttk
class MyApp(Tk):
def __init__(self):
Tk.__init__(self)
container = ttk.Frame(self)
container.pack(side="top", fill="both", expand = True)
self.frames = {}
for F in (PageOne, PageTwo):
frame = F(container, self)
self.frames[F] = frame
frame.grid(row=0, column=0, sticky = NSEW)
self.show_frame(PageOne)
def show_frame(self, cont):
frame = self.frames[cont]
frame.tkraise()
def get_page(self, classname):
'''Returns an instance of a page given its class name as a string'''
for page in self.frames.values():
if str(page.__class__.__name__) == classname:
return page
return None
def test_get_page(self, page_class):
return self.frames[page_class]
class PageOne(ttk.Frame):
def __init__(self, parent, controller):
self.controller=controller
ttk.Frame.__init__(self, parent)
ttk.Label(self, text='PageOne').grid()
self.testText = Text(self, height=2, width=30)
button1 = ttk.Button(self, text='Next Page',
command=lambda: controller.show_frame(PageTwo))
self.testText.grid()
button1.grid()
class PageTwo(ttk.Frame):
def __init__(self, parent, controller):
self.controller=controller
ttk.Frame.__init__(self, parent)
ttk.Label(self, text='PageTwo').grid()
button1 = ttk.Button(self, text='Previous Page',
command=self.testButton)#controller.show_frame(PageOne))
button1.grid()
def testButton(self):
page = self.controller.test_get_page(PageOne)
page.testText.insert(END,'testing')
self.controller.show_frame(PageOne)
app = MyApp()
app.title('Multi-Page Test App')
app.mainloop()
The expected result would have been for PageOne's "testText" widget to show "testing" once the 'Previous Page' button on PageTwo was clicked, but instead I got the following error:
"Exception in Tkinter callback
Traceback (most recent call last):
File "C:\Users\Max\AppData\Local\Programs\Python\Python36-32\lib\tkinter\__init__.py", line 1702, in __call__
return self.func(*args)
File "C:\Users\Max\Dropbox\Programación\prueba.py", line 54, in testButton
page.testText.insert(0,'testing')
AttributeError: 'PageOne' object has no attribute 'testText'"

Answer 1

The error is given in the stack trace. The 'testText' variable is not currently an instance variable of the PageOne object. You should set self.testText = Text(self, height=2, width=30)