How do I link python tkinter widgets created in a for loop?

Question

I want to create Button and Entry(state=disabled) widgets with a for loop. The number of widgets to be created will be a runtime argument. What I want is that every time I click the button, the corresponding entry will become enabled(state="normal"). The problem in my code is that any button I click, it only affects the last entry widget. Is there anyway to fix this.? Here is my code:

from tkinter import *

class practice:
    def __init__(self,root):
        for w in range(5):
            button=Button(root,text="submit",
                command=lambda:self.enabling(entry1))
            button.grid(row=w,column=0)
            entry1=Entry(root, state="disabled")
            entry1.grid(row=w,column=1)

    def enabling(self,entryy):
        entryy.config(state="normal")

root = Tk()
a = practice(root)
root.mainloop()

Anand S Kumar · Accepted Answer · 2015-08-16 17:27:24Z

4

Few issues in your code -

You should keep the buttons and entries you are creating and save them in an instance variable, most probably it would be good to store them in a list , then w would be the index for each button/entry in the list.
When you do lambda: something(some_param) - the function value of some_param() is not substituted, till when the function is actually called, and at that time, it is working on the latest value for entry1 , hence the issue. You should not depend on that and rather you should use functools.partial() and send in the index of Button/Entry to enable.

Example -

from tkinter import *
import functools

class practice:
    def __init__(self,root):
        self.button_list = []
        self.entry_list = []
        for w in range(5):
            button = Button(root,text="submit",command=functools.partial(self.enabling, idx=w))
            button.grid(row=w,column=0)
            self.button_list.append(button)
            entry1=Entry(root, state="disabled")
            entry1.grid(row=w,column=1)
            self.entry_list.append(entry1)

    def enabling(self,idx):
            self.entry_list[idx].config(state="normal")


root = Tk()
a = practice(root)

root.mainloop()

answered Aug 16, 2015 at 17:27

Anand S Kumar

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2 Comments

Crstn Over a year ago

Wow. that answers my problem! Thank you!

Anand S Kumar Over a year ago

@Crstn Please do note that the first point I said (in my answer) is important. Otherwise you would end up in mysterious bugs.

Terry Jan Reedy · Accepted Answer · 2015-08-16 17:42:57Z

Whenever people have problem with a function created with a lambda expression instead of a def statement, I recommend rewriting the code with a def statement until it works right. Here is the simplest fix to your code: it reorders widget creation and binds each entry to a new function as a default arg.

from tkinter import *

class practice:
    def __init__(self,root):
        for w in range(5):
            entry=Entry(root, state="disabled")
            button=Button(root,text="submit",
                command=lambda e=entry:self.enabling(e))
            button.grid(row=w,column=0)
            entry.grid(row=w,column=1)

    def enabling(self,entry):
        entry.config(state="normal")

root = Tk()
a = practice(root)
root.mainloop()

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