Python - retrieving value from tk entry box in separate class

Question

I'm trying to get a value entered into a tkinter Entry widget which is set in a class. I can use the attribute.get() to retrieve the value when the widget isn't in a class but I'm not sure how to call it when it is in a class.

The error i receive is:

  File "C:/Users/ABour/Python Scripts/test/PassVarSX.py", line 12, in Enter_Inputs
    xf_In = int(self.e_xf.get())
AttributeError: 'StartPage' object has no attribute 'e_xf'

The class containing the widget is called StartPage and the widget is called e_xf, the function using .get() is called Enter_Inputs

Thank you in advance for any help, I'm running this on Spyder, Python v3.6

import tkinter as tk
from tkinter import ttk

LARGE_FONT= ("Verdana", 12)

def To_Print(self):
    xf = Enter_Inputs(self,'xf')
    print('xf = ', xf)

def Enter_Inputs(self,x): # Enter inputs from values typed in

      xf_In = int(self.e_xf.get())

      if x == 'xf':
          x = float(xf_In)/100 

      return x


class TestApp(tk.Tk):

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

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

        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 = {}

        frame = StartPage(container, self)

        self.frames[StartPage] = frame

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

        self.show_frame(StartPage)

    def show_frame(self, cont):

        frame = self.frames[cont]
        frame.tkraise()


class StartPage(tk.Frame):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self,parent)


        label = ttk.Label(self, text="Start Page", font=LARGE_FONT)
        label.grid(row=0, columnspan = 2)


        l_xf = tk.Label(self, text="% xA of Feed")
        l_xf.grid(row=1)

        e_xf = tk.Entry(self)
        e_xf.grid(row=1, column=1)


        b_run = tk.Button(self, text="Click to Run", command=lambda: To_Print(self))
        b_run.grid(row=2, column=0, columnspan = 2)  


app = TestApp()
app.mainloop()

Answer 1

As you pass self to To_Print method and you want from self to call the e_xf field, you should declare e_xf as a data member of the class.

You can do it by simply change the line

self.e_xf = tk.Entry(self)
self.e_xf.grid(row=1, column=1)

By that the e_xf is an instance member, and you should be able to call it from Enter_Inputs function.