Tkinter Entry widget stays empty in larger programs (Python 2)

Question

I want to make a program where, after clicking on a button, a user gets asked for its name, after which the program continues. I'm stuck on making the popup return the textstring that has been entered in the popup. At first I thought it was my code, but the I decided to make a second program where it just asks the name, prints it, prints it length and its type. In that second program, everything works as it should. I'm having a very hard time figuring out why it doesn't in the first (larger) program. I've already read (Why is Tkinter Entry's get function returning nothing?) and, even though my .get() function occurs after my .mainloop, it still doesn't work; in that same thread they propose using classes, which is something I know absolutely nothing about. If possible can anyone point out what I'm missing in my larger program?

---

Large Program

---

from Tkinter import *

root = Tk()
root.title("Ask-name-SUB")

def getname(usertype):
    getname = Tk()
    getname.title("Get name popup")
    def abort():
        getname.destroy()
    name = StringVar()
    c = LabelFrame(getname, text = "Your name:")
    c.pack()
    d = Entry(getname, textvariable=name)
    d.pack(side="right")
    d.bind("<Return>", lambda event: getname.destroy())
    e = Button(getname, text = "Cancel", command=lambda: abort())
    e.pack()

    getname.mainloop()
    name = (name.get())
    print "Print name, its length, its type"
    print name
    print len(name)
    print type(name)

top = Frame(root)
top.pack(side="top")
bottom = Frame(root)
bottom.pack(side="bottom")
def killit():
    root.destroy()

cancel = Button (bottom, text = "Cancel", command=lambda: killit())
cancel.pack()
askname = Button (top, text = "Enter your name", command=lambda: getname("testuser"))
askname.pack()
root.mainloop()

---

Small Program

---

    from Tkinter import *

def getname(usertype):
    getname = Tk()
    getname.title("Get name popup")
    def abort():
        getname.destroy()
    name = StringVar()
    c = LabelFrame(getname, text = "Your name:")
    c.pack()
    d = Entry(getname, textvariable=name)
    d.pack(side="right")
    d.bind("<Return>", lambda event: getname.destroy())
    e = Button(getname, text = "Cancel", command=lambda: abort())
    e.pack()

    getname.mainloop()
    name = (name.get())
    print "Print name, its length, its type"
    print name
    print len(name)
    print type(name)


getname("testuser")

Answer 1

I can't run your large program - probably you have wrong indentions.

I see two problems:

• program should have only one mainloop() - and it can be your problem.
• we use Tk() to create main window, and Toplevel() to create other windows.

Besides you use name getname as function name and as second window instance so it is very misleading.

I create global var_name to keep name and later I use it inside function.

from Tkinter import *

def get_name(usertype):

    win = Toplevel()
    win.title("Get name popup")

    f = LabelFrame(win, text = "Your name:")
    f.pack()

    # use global `name` which was created outside function
    e = Entry(win, textvariable=var_name)
    e.pack(side="right")
    e.bind("<Return>", lambda event: win.destroy())

    b = Button(win, text = "Cancel", command=win.destroy)
    b.pack()

# --- main --

root = Tk()
root.title("Ask-name-SUB")

# global variable
var_name = StringVar()

b = Button(root, text="Enter your name", command=lambda: get_name("testuser"))
b.pack()

b = Button(root, text="Cancel", command=root.destroy)
b.pack()

root.mainloop()

# --- after --
name = var_name.get()
print "Print name, its length, its type"
print name, len(name), type(name)

---

EDIT:

To makes popup window more universal you can use arguments - displayed text and variable for result.

def get_value(text, variable):

and then you can use it with different text and different variable - ie. for name or for address.

from Tkinter import *

def get_value(text, variable):

    win = Toplevel()
    win.title("Get value")

    f = LabelFrame(win, text=text)
    f.pack()

    e = Entry(win, textvariable=variable)
    e.pack(side="right")
    e.bind("<Return>", lambda event: win.destroy())

    b = Button(win, text = "Cancel", command=win.destroy)
    b.pack()

# --- main --

root = Tk()
root.title("Ask-name-SUB")

# global variables
var_name = StringVar()
var_address = StringVar()

b = Button(root, text="Enter your name", command=lambda: get_value("Your name:", var_name))
b.pack()

b = Button(root, text="Enter your address", command=lambda: get_value("Your address:", var_address))
b.pack()

b = Button(root, text="Cancel", command=root.destroy)
b.pack()

root.mainloop()

# --- after --

name = var_name.get()
print "Print name, its length, its type"
print name, len(name), type(name)

address = var_address.get()
print "Print address, its length, its type"
print address, len(address), type(address)