Set A Default Value For A Ttk Combobox

I'm using Python 3.2.1 in Arch Linux x86_64. This one is really driving me crazy: I just want to have a default, preselected value for a ttk.Combobox as soon as I grid it. This is

Solution 1:

The problem is that the instance of StringVar is getting garbage-collected. This is because it's a local variable due to how you wrote your code.

One solution is to use a class so that your StringVar persists:

from tkinter import Tk, StringVar, ttk

classApplication:

    def__init__(self, parent):
        self.parent = parent
        self.combo()

    defcombo(self):
        self.box_value = StringVar()
        self.box = ttk.Combobox(self.parent, textvariable=self.box_value, 
                                state='readonly')
        self.box['values'] = ('A', 'B', 'C')
        self.box.current(0)
        self.box.grid(column=0, row=0)

if __name__ == '__main__':
    root = Tk()
    app = Application(root)
    root.mainloop()

Solution 2:

When your function 'combo' exits, the local variable 'value' is destroyed. You need a persistent variable, such as a global variable or a variable that is a property of a class so that the value isn't garbage-collected while the widget still exists.

Solution 3:

The get() method can be used within your function to rename the StringVar and save it under another name to avoid losing it altogether via garbage collection.

value = StringVar()

keepvalue = value.get()

then use keepvalue instead of value:

box = ttk.Combobox(root, textvariable=keepvalue, state='readonly')

This had 'A' showing in the combobox for me.