How to set a default string value on a Tkinter Spinbox?

To set a default string value on a Tkinter Spinbox, we will have to use the set method. Let us take an example and see how to create a spinbox with a set of string values and then set a default string.

Steps

• Import the tkinter library and create an instance of tkinter frame.

• Set the size of the frame using geometry method.

• Create a set of strings and save it in a variable, data.

• Next, use the StringVar() constructor to create a StringVar object. It helps to manage the value of a widget, which is Spinbox in this case. If you don't pass any parameters, then it defaults to the root window.

• Create a spinbox and set its values by passing the data values.

• Assign the StringVar object to the textvariable of the spinbox. Using textvariable, you can easily update the text of a widget.

• Set a default value for the spinbox by using the set method. Here, we have picked a value from data and set it as default. var.set('Truck'). You can also use var.set(data[2]).

• Finally, run the mainloop of the application window.

Example

from tkinter import *

win = Tk()
win.geometry('700x350')
win.title('Spinbox')

data = ['Car', 'Bus', 'Truck', 'Bike', 'Airplane']

var = StringVar(win)

my_spinbox = Spinbox(win, values=data, textvariable=var, width=20, font="Calibri, 12")
my_spinbox.pack(padx=20, pady=20)
var.set('Truck')

win.mainloop()

Alternative Methods

Using insert() Method

You can also set a default value using the insert() method ?

from tkinter import *

win = Tk()
win.geometry('700x350')
win.title('Spinbox with Insert')

data = ['Car', 'Bus', 'Truck', 'Bike', 'Airplane']

my_spinbox = Spinbox(win, values=data, width=20, font="Calibri, 12")
my_spinbox.pack(padx=20, pady=20)
my_spinbox.insert(0, 'Bus')  # Insert 'Bus' at index 0

win.mainloop()

Setting Default During Widget Creation

You can also use the textvariable with a pre−set StringVar ?

from tkinter import *

win = Tk()
win.geometry('700x350')
win.title('Pre-set Default Spinbox')

data = ['Car', 'Bus', 'Truck', 'Bike', 'Airplane']

var = StringVar(value='Airplane')  # Set default value during creation

my_spinbox = Spinbox(win, values=data, textvariable=var, width=20, font="Calibri, 12")
my_spinbox.pack(padx=20, pady=20)

win.mainloop()

Output

The spinbox will display with 'Truck' as the default selected value. Users can click the up/down arrows or manually type to change the selection from the predefined list.

Comparison

Conclusion

Use StringVar.set() method for dynamic default values in Tkinter Spinbox widgets. For simple cases, insert() method works well, while StringVar(value=) provides clean initialization during widget creation.