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I've made a simple combobox in python using Tkinter, I want to retrieve the value selected by the user. After searching, I think I can do this by binding an event of selection and call a function that will use something like box.get(), but this is not working. When the program starts the method is automatically called and it doesn't print the current selection. When I select any item from the combobox no method gets called. Here is a snippet of my code: 

    self.box_value = StringVar()
    self.locationBox = Combobox(self.master, textvariable=self.box_value)
    self.locationBox.bind("<<ComboboxSelected>>", self.justamethod())
    self.locationBox['values'] = ('one', 'two', 'three')
    self.locationBox.current(0)

This is the method that is supposed to be called when I select an item from the box: 

def justamethod (self):
    print("method is called")
    print (self.locationBox.get())

Can anyone please tell me how to get the selected value?

EDIT: I've corrected the call to justamethod by removing the brackets when binding the box to a function as suggested by James Kent. But now I'm getting this error:

TypeError: justamethod() takes exactly 1 argument (2 given)

EDIT 2: I've posted the solution to this problem.

Thank You.

Dania
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    in your `self.locationBox.bind` you are calling the function by adding the brackets after the function name, remove these and it should work. so change `self.justamethod()` to `self.justamethod` – James Kent Jul 07 '15 at 09:23
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    @JamesKent Thanks a lot, I always keep forgetting to remove the brackets. I removed them, but I'm getting this error, TypeError: justamethod() takes exactly 1 argument (2 given). Cany you please tell me how to solve it? Thanks. – Dania Jul 07 '15 at 09:29
  • the reason for the `TypeError` is because when the event is triggered, an event object is passed to the function you bound to as one of the arguments, if you want to see some of the attributes that can be got from this object, see this page: http://effbot.org/tkinterbook/tkinter-events-and-bindings.htm – James Kent Jul 07 '15 at 12:41

2 Answers2

14

I've figured out what's wrong in the code.

First, as James said the brackets should be removed when binding justamethod to the combobox.

Second, regarding the type error, this is because justamethod is an event handler, so it should take two parameters, self and event, like this, 

def justamethod (self, event):

After making these changes the code is working well.

Dania
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from tkinter import ttk
from tkinter import messagebox
from tkinter import Tk



root = Tk()

root.geometry("400x400")
#^ width - heghit window :D


cmb = ttk.Combobox(root, width="10", values=("prova","ciao","come","stai"))
#cmb = Combobox

class TableDropDown(ttk.Combobox):
    def __init__(self, parent):
        self.current_table = tk.StringVar() # create variable for table
        ttk.Combobox.__init__(self, parent)#  init widget
        self.config(textvariable = self.current_table, state = "readonly", values = ["Customers", "Pets", "Invoices", "Prices"])
        self.current(0) # index of values for current table
        self.place(x = 50, y = 50, anchor = "w") # place drop down box 

def checkcmbo():

    if cmb.get() == "prova":
        messagebox.showinfo("What user choose", "you choose prova")

    elif cmb.get() == "ciao":
        messagebox.showinfo("What user choose", "you choose ciao")

    elif cmb.get() == "come":
        messagebox.showinfo("What user choose", "you choose come")

    elif cmb.get() == "stai":
        messagebox.showinfo("What user choose", "you choose stai")

    elif cmb.get() == "":
        messagebox.showinfo("nothing to show!", "you have to be choose something")




cmb.place(relx="0.1",rely="0.1")

btn = ttk.Button(root, text="Get Value",command=checkcmbo)
btn.place(relx="0.5",rely="0.1")

root.mainloop()
tfv
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