Accessing class variables outside the class in python

Question

I have a tkinter class. I want to access the value of entry field outside the class. I have tried doing it by creating a function but it is printing the address and not the value. Here is my code

class first:
    def __init__(self, root):
        self.root = root
        self.root.title('First window')
        self.root.geometry('1350x700+0+0')
        
        self.mystring = tkinter.StringVar(self.root)


        self.txt_id = Entry(self.root, textvariable=self.mystring, font=("Times New Roman", 14), bg='white')
        self.txt_id.place(x=200, y=400, width=280)

    btn_search = Button(self.root, command=self.get_id)
        btn_search.place(x=100, y=150, width=220, height=35)

     def get_id(self):
        print(self.mystring.get())
        return self.mystring.get()
     print(get_id)
print(first.get_id)

the output i am getting by calling first.get_id is <function first.get_id at 0x0000016A7A41B430> I have also tried to store this value in a global variable but outside class it gives variable not deifned error. Can anyone help me doing this?

We cannot run your code, it's not a minimal complete example. — timgeb, Apr 30 '21 at 11:19
You need to create an instance of the class in order to access its instance variable or function, except they are class variable and function. — acw1668, Apr 30 '21 at 11:23
Your are not *calling* ``first.get_id``, you are looking it up. Even then, you must/should call methods *on an instance*, not the class. — MisterMiyagi, Apr 30 '21 at 11:24
You mean this way @MisterMiyagi `value = first id_value=value.get_id print(id_value)`. It is printing the same thing. — Anmol, Apr 30 '21 at 11:40
@acw1668 please can you show me how? I am doing it this way but not getting the desired value. — Anmol, Apr 30 '21 at 11:46
You are already doing lots of calls, and you are instantiating lots of classes. It's the ``(`` ``)`` thingies. Neither ``value = first`` nor ``id_value=value.get_id`` has enough of them. — MisterMiyagi, Apr 30 '21 at 11:48

score 2 · Accepted Answer · answered Apr 30 '21 at 12:09

First you need to create an instance of the class, then you can use that instance to access its instance variable and function.

Below is a simple example based on your code

import tkinter as tk

class First:
    def __init__(self, root):
        self.root = root
        self.root.title('First window')
        self.root.geometry('1350x700+0+0')
        
        self.mystring = tk.StringVar(self.root)

        self.txt_id = tk.Entry(self.root, textvariable=self.mystring, font=("Times New Roman", 14), bg='white')
        self.txt_id.place(x=200, y=400, width=280)

        btn_search = tk.Button(self.root, text="Show in class", command=self.get_id)
        btn_search.place(x=100, y=150, width=220, height=35)

    def get_id(self):
        val = self.mystring.get()
        print("inside class:", val)
        return val

root = tk.Tk()

# create an instance of First class
app = First(root)

def show():
    # get the text from the Entry widget
    print("outside class:", app.get_id())

tk.Button(root, text="Show outside class", command=show).pack()

root.mainloop()

Note that I have change class name from first to First because it is normal practise.

I will try this way. I think I am not getting the things clearly. — Anmol, Apr 30 '21 at 12:43

Accessing class variables outside the class in python

1 Answers1