Share variable between tkinter frames, using shared data approach

Question

So basically i have a program with 2 frames, where in the first one the user upload a file and in the second one the path of the file is put it on a label. Im using this elegant approach to share data between my frames, but is not working, in my second frame the self.app_data["filePath"] is undefined even after recieve the value of filename variable.

import tkinter as tk
import tkinter.filedialog as filedialog
from tkinter import ttk

LARGE_FONT = ("Verdana", 12)


class SeaofBTCapp(tk.Tk):

   def __init__(self, *args, **kwargs):

        ## Frame inicial

       tk.Tk.__init__(self, *args, **kwargs)

       tk.Tk.wm_title(self, "Carrefour NLC")
       tk.Tk.geometry(self, "500x400")
       tk.Tk.resizable(self, 0, 0)
       container = tk.Frame(self)

       container.pack(side="top", fill="both", expand=True)
       container.grid_rowconfigure(0, weight=1)
       container.grid_columnconfigure(0, weight=1)

       self.frames = {}
       self.app_data = {"filePath":  tk.StringVar()}
       for F in (StartPage, PageOne):

           frame = F(container, self)

           self.frames[F] = frame

           frame.grid(row=0, column=0, sticky="nsew")

       self.show_frame(StartPage)


   def show_frame(self, cont):
       frame = self.frames[cont]
       frame.tkraise()
       return frame


class StartPage(tk.Frame):
   def __init__(self, parent, controller):
       tk.Frame.__init__(self, parent)
       self.controller =  controller
       label = tk.Label(self, text="Upload File", font=LARGE_FONT)
       label.pack(pady=20, padx=100)


       def fileOpen():
           filename = filedialog.askopenfilename()
           if filename:
                ## Setting file path if file exist
               print(filename)
               self.controller.app_data["filePath"].set(filename)


       containerRadio = tk.Frame(self)
       buttonFile = ttk.Button(containerRadio, text="Open File",command=lambda:fileOpen())
       containerRadio.pack()
       buttonFile.pack(side="left")


       containerBottom = tk.Frame(self)

       button2 = ttk.Button(containerBottom, text="Next",
                               command=lambda: controller.show_frame(PageOne))
       containerBottom.pack(side="bottom", pady=20)
       button2.pack(side="left")


class PageOne(tk.Frame):

    def __init__(self, parent, controller):
       tk.Frame.__init__(self, parent)
       self.controller =  controller
       label = tk.Label(self, text="File Path", font=LARGE_FONT)
       ## Empty File path
       labelPath = tk.Label(self, text=self.controller.app_data["filePath"].get(), font=LARGE_FONT)
       label.pack(pady=20, padx=100)
       labelPath.pack(pady=20, padx=100)

       containerBottom = tk.Frame(self)
       button2 = ttk.Button(containerBottom, text="Back",
                               command=lambda: controller.show_frame(StartPage))
       containerBottom.pack(side="bottom", pady=20)
       button2.pack(side="left")

app = SeaofBTCapp()
app.mainloop()

i guess the main issue is the self.controller reference somehow is getting lost inside of fileOpen function, i tried to pass a reference of self.controller to the function but still didnt worked.

Thanks in advance, i apreciate any help.

Edit

The answer provided by stovfl textvariable=self.controller.app_data["filePath"] worked inside of the label, but if i try to set self.controller.app_data["filePath"] to the path variable,path remains undefined.

class PageOne(tk.Frame):
     def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller =  controller
        path = self.controller.app_data["filePath"].get()
        ##Path is empty
        print('path:',path)
        ##textvariable get the value of self.controller.app_data["filepath"]
        labelPath = tk.Label(self, 
              textvariable=self.controller.app_data["filePath"], font=LARGE_FONT)
        label.pack(pady=20, padx=100)
        labelPath.pack(pady=20, padx=100)