Python - Button depending on box

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I started with designing a program to learn how to program, however I’m having a hard time doing the following:

  1. The person places the information in the text box
  2. The Button fetches this information and performs a function.

Can help?

from tkinter import *

def Connect():


def main_screen():
    global screen
    screen = Tk()
    screen.geometry ("800x600")
    screen.title ("Helpdesk")
    Label (text = "Helpdesk 1.0", bg = "grey", width = "300", height = "2", font = ("calibri", 13,)).pack()
    Label (text= "IP Adrress", bg = "white", width = "250", height = "2", font = ("calibri",12,)).pack()
    Box = Entry ().pack()
    Button (text= "Connect", height = "2", width = "30", command = Connect).pack()




    screen.mainloop ()

main_screen ()
python tkinter

1 answer

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First of all, you need to fix that line:

Box = Entry().pack()

The problem here is that the method pack() does not return anything, so its variable Box will be empty (with None). To store the object Entry in Box you need to split it into two lines:

Box = Entry()
Box.pack()

Now, your problem is passing the data from one function to another. As the function called by Button cannot have parameters, you need to use some alternative method to pass the object Entry for the same.

One of the simplest ways is to use global variables: For this use global in both roles:

def main_screen():
    global Box
    # ... restante da funcao normal ...

def Connect():
    global Box
    ip_digitado = Box.get() # acessa o Entry criado na outra funcao
    print(ip_digitado)

Another way is to use the scope of a function to hold the variable (called closure). The module functools has the function partial that’s what this:

By creating the Button:

Button(..., command=functools.partial(Connect, Box)).pack()

When calling using this function partial it is possible to pass a parameter to Connect which is of local scope within main_screen; That way you don’t need to use global, just receive the parameter:

def Connect(box):
    ip_digitado = box.get()
    print(ip_digitado)

The third, and most recommended, form is to use classes, and then store the objects you will need as instance attributes:

class App:
    def __init__(self, root):
        self.screen = root

    def main_screen(self):
        self.screen.geometry("800x600")
        self.screen.title("Helpdesk")
        Label(self.screen, text="Helpdesk 1.0", bg="grey", width="300",
            height="2", font=("calibri", 13,)).pack()
        Label(self.screen, text="IP Adrress", bg="white", width="250",
            height="2", font=("calibri",12,)).pack()
        self.box = Entry(self.screen)
        self.box.pack()
        Button(self.screen, text="Connect", height="2", width="30", 
            command=self.connect).pack()
        self.screen.mainloop()

    def connect(self):
        ip_digitado = self.box.get()
        print(ip_digitado)

screen = Tk()
App(screen).main_screen()

As you can see the attribute self.box is accessible in any class method, making it independent.

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