Tkinter get() function is not returning anything

Question

I am trying to write a program using a tkinter GUI to calculate a few things. My get() function isn't working and I'm not sure why

from tkinter import *
from math import *
root = Tk()

v = 0
l = 0
w = 0
t1 = 0
t0 = 0

label1 = Label(root, text = "Enter value for length (mm) :").grid(columnspan = 2, sticky = "E")
length = Entry(root).grid(row = 0, column = 2)

label2 = Label(root, text = "Enter value for volume (mm^2) :").grid(columnspan = 2, sticky = "E")
volume = Entry(root).grid(row = 1, column = 2)

label3 = Label(root, text = "Enter value for the thickness of the cylinder (mm) :").grid(columnspan = 2, sticky = "E")
thickness = Entry(root).grid(row = 2, column = 2)

label4 = Label(root, text = "Enter value for starting temperature (K) :").grid(columnspan = 2, sticky = "E")
st_T = Entry(root).grid(row = 3, column = 2)

label5 = Label(root, text = "Enter value for finishing temperature (K) :").grid(columnspan = 2, sticky = "E")
end_T = Entry(root).grid(row = 4, column = 2)

def save():
    v = volume.get()
    l = length.get()
    w = thickness.get()
    t0 = st_T.get()
    t1 = end_T.get()

    global values 
    values = [v, l, w, t1, t0]

answer = StringVar()
labelans = Label(root, textvariable = answer).grid(columnspan = 3,)
answer.set("Answer = ")

def area_circle():
    global answer
    answer =  v / l
    print(answer)

Button(root, text = "Submit", command = save()).grid(row = 6, column = 0)

root.mainloop()

Obviously there are variables i'm not using yet but im trying to get the first part right first.

For v the error displayed is: Message='NoneType' object has no attribute 'get'

This is a duplicate of two questions. The other one it's a duplicate of is http://stackoverflow.com/q/1101750/7432 — Bryan Oakley, Jul 24 '19 at 12:55

score 1 · Answer 1 · answered Jul 24 '19 at 12:14

The Grid geometry manager puts the widgets in a 2-dimensional table. The master widget is split into a number of rows and columns, and each “cell” in the resulting table can hold a widget.

What is important Grid() is returning NoneValue

if you are doing like:
length = Entry(root).grid(row = 0, column = 2)
in your variable length you will have NoneValue

you should do it like :
length = Entry(root)
length.grid(row = 0, column = 2)

your code:

label1 = Label(root, text = "Enter value for length (mm) :")
label1.grid(columnspan = 2, sticky = "E")
length = Entry(root)
length.grid(row = 0, column = 2)

label2 = Label(root, text = "Enter value for volume (mm^2) :")
label2.grid(columnspan = 2, sticky = "E")
volume = Entry(root)
volume.grid(row = 1, column = 2)

label3 = Label(root, text = "Enter value for the thickness of the cylinder (mm) :")
label3.grid(columnspan = 2, sticky = "E")
thickness = Entry(root)
thickness.grid(row = 2, column = 2)

label4 = Label(root, text = "Enter value for starting temperature (K) :")
label4.grid(columnspan = 2, sticky = "E")
st_T = Entry(root)
st_T.grid(row = 3, column = 2)

label5 = Label(root, text = "Enter value for finishing temperature (K) :")
label5.grid(columnspan = 2, sticky = "E")
end_T = Entry(root)
end_T.grid(row = 4, column = 2)

def save():
    v = volume.get()
    l = length.get()
    w = thickness.get()
    t0 = st_T.get()
    t1 = end_T.get()

    global values
    values = [v, l, w, t1, t0]

answer = StringVar()
labelans = Label(root, textvariable = answer).grid(columnspan = 3,)
answer.set("Answer = ")

def area_circle():
    global answer
    answer =  v / l
    print(answer)

Button(root, text = "Submit", command = save()).grid(row = 6, column = 0)

root.mainloop()

output:

score 0 · Answer 2 · answered Jul 24 '19 at 11:08

0

The command argument should be a callback, not the actual call:

Button(root, text="Submit", command=save).grid(row=6, column=0)

answered Jul 24 '19 at 11:08

ipaleka

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i changed it but it still returns the NoneType error as before – Dhardwall Jul 24 '19 at 11:20
Just delete those parentheses on save, it will work. – ipaleka Jul 24 '19 at 11:25
Like I said, i removed the parentheses and the NoneType error remained – Dhardwall Jul 24 '19 at 11:28
[screenshot](https://imgur.com/a/oJ1oTyT) – ipaleka Jul 24 '19 at 11:42
As @ncica pointed out, and what you haven't mentioned, after solving initial bug another is now cleary exposed after actually clicking the button. Please refer to his answer for a solution. – ipaleka Jul 24 '19 at 15:47

Tkinter get() function is not returning anything

2 Answers2