dropdown in tkinter with code examples

The dropdown menu is a widely used graphical user interface element that lists the items to select from a predetermined set of options. It is widely used in modern-day programming when developing graphical user interface (GUI) applications in programming languages like Python.

Tkinter is one of the most popular GUI frameworks for Python developers. It includes an extensive set of widgets that can be used to create a GUI and also provides a set of options to modify their appearance and behaviour, including the dropdown menu.

In this article, you will learn how to create a dropdown menu in tkinter. We will also create practical examples along the way to help drive the concept home.

Creating a Dropdown menu in Tkinter

Creating a dropdown menu is relatively simple in tkinter. You should follow the following steps.

  1. Import tkinter

The first step to creating a dropdown menu in tkinter is importing the tkinter library. You can do this with the following code.

import tkinter as tk

  1. Create the tkinter application window

The dropdown menu will be placed on the tkinter window. Therefore, you should create the tkinter window with the following code.

window = tk.Tk()

  1. Create the list of options

The next step is to create a list of options that will be displayed in the dropdown menu. You can do this by creating a tuple of your options.

options = ("Option 1", "Option 2", "Option 3", "Option 4")

  1. Create the dropdown menu

Next, create a variable for the selected option, which will be displayed in the dropdown menu’s text widget. This variable is crucial because it stores the current value in the dropdown menu. Then, create the dropdown menu widget using the OptionMenu method. Finally, place the dropdown menu widget on the tkinter window.

selected_option = tk.StringVar(window)
selected_option.set(options[0])
drop_down_menu = tk.OptionMenu(window, selected_option, *options)
drop_down_menu.pack()

As you can see from the above code, the OptionMenu method takes a few parameters. They are:

  • window – A reference to the window element, where the dropdown menu will be placed.
  • selected_option– A reference to the selected option, i.e., the variable storing the current value in the dropdown.
  • *options-The set of values to be displayed in the dropdown menu.
  1. Display the tkinter window

Finally, call the mainloop() method that will display the tkinter window.

window.mainloop()

That's it! You have created a dropdown menu in tkinter using the OptionMenu method. Let's work through a few examples to help reinforce the concept.

Example 1: Creating a simple dropdown menu

Suppose we want to create a simple dropdown menu with two options, “Hello” and “World.” The following code will do that.

import tkinter as tk

window = tk.Tk()

options = ("Hello", "World")
selected_option = tk.StringVar(window)
selected_option.set(options[0])

drop_down_menu = tk.OptionMenu(window, selected_option, *options)
drop_down_menu.pack()

window.mainloop()

When you run this code, you'll see a tkinter window with a dropdown menu containing the “Hello” option initially selected.

Example 2: Using the selected option from the dropdown menu

Suppose we want to know which option was selected from the dropdown menu. We can achieve that by using a button widget with a command that prints the selected option value to the console.

import tkinter as tk

window = tk.Tk()

options = ("Option 1", "Option 2", "Option 3", "Option 4")
selected_option = tk.StringVar(window)
selected_option.set(options[0])

drop_down_menu = tk.OptionMenu(window, selected_option, *options)
drop_down_menu.pack()

button = tk.Button(window, text="Get Selected Option", command=lambda: print(selected_option.get()))
button.pack()

window.mainloop()

In this code example, we added a button widget with the command that prints the selected option's value to the console when clicked. As such, when you run the code, you should see a tkinter window with a dropdown menu and a button.

Example 3: Creating a Dynamic Dropdown menu

In the previous examples, the dropdown menu options were static, meaning they did not change during the application’s lifetime. However, you can create a dynamic dropdown list by linking the list to a Python list variable. Any modification to the Python list variable will reflect on the dropdown list.

import tkinter as tk

window = tk.Tk()

options = ["apple", "orange", "banana"]
selected_option = tk.StringVar(window)
selected_option.set(options[0])

drop_down_menu = tk.OptionMenu(window, selected_option, *options)
drop_down_menu.pack()

new_option = tk.Entry(window)
new_option.pack()

add_button = tk.Button(window, text="Add Option", command=lambda: add_option(options, new_option))
add_button.pack()

def add_option(option_list, entry):
    option_list.append(entry.get()) 
    selected_option.set(option_list[0])
    drop_down_menu['menu'].delete(0, 'end')
    for option in option_list:
        drop_down_menu['menu'].add_command(label=option, command=tk._setit(selected_option, option))

window.mainloop()

In this example, we create a drop-down menu with three preset values ‘apple,’ ‘orange,’ and ‘banana.’ We then allow the user to input a new value into an Entry widget. On clicking the “Add Option” button, we append the input value into our options list and also update our dropdown menu.

Conclusion

In this article, we have discussed how to create a dropdown menu using tkinter. The dropdown menu is an essential GUI element for any application that requires data input. We learned how the OptionMenu method of tkinter is used to create a dropdown menu. We have also gone over detailed examples detailing the creation of a dropdown menu with static as well as a dynamic option list. I hope that you found this article informative and helpful.

Creating a dropdown menu in tkinter is an essential skill that any Python developer should know when creating graphically rich user interfaces. In this article, we have gone over the basics of creating a dropdown menu in tkinter using the OptionMenu method, how to set the default value of the dropdown menu, and how to retrieve the selected value.

There are various ways you can customize your dropdown menus in tkinter. For instance, you can change the background and foreground colors, change the font and font size, and even change the width and height of the dropdown menu widget.

Additionally, you can change the behavior of the dropdown menu by adding a command that executes when a new selection is made in the menu. You can also use the tkinter trace method to keep track of the variable selected_option and know when its value changes.

Here's an example of how you can use the command attribute to keep track of when the dropdown menu selection is changed.

import tkinter as tk

window = tk.Tk()

options = ["Option 1", "Option 2", "Option 3", "Option 4"]
selected_option = tk.StringVar(window)
selected_option.set(options[0])

def option_selected(*args):
    print(selected_option.get())

selected_option.trace("w", option_selected)

drop_down_menu = tk.OptionMenu(window, selected_option, *options, command=option_selected)
drop_down_menu.pack()

window.mainloop()

In this example, we added a trace to the selected_option variable to call the option_selected function every time the selected option in the dropdown menu changes. This can be helpful when you want to execute some code when a new dropdown menu selection is made.

Another advanced feature in tkinter dropdown menus is creating cascading menus. A cascading menu is a hierarchical menu that expands on the selection of another option in the dropdown menu.

Here's an example of a cascading dropdown menu built with tkinter:

import tkinter as tk

window = tk.Tk()

options = ["Main Menu", "Option 1", "Option 2", "Option 3"]
selected_option = tk.StringVar(window)
selected_option.set(options[0])


def option_selected(*args):
    if selected_option.get() == "Main Menu":
        sub_menu = sub_menu_widget()
        drop_down_menu['menu'].delete(1, 'end')
        drop_down_menu['menu'].insert_cascade(1, label="Sub Menu", menu=sub_menu)

    elif selected_option.get() == "Option 1":
        print("Option 1 selected")

    elif selected_option.get() == "Option 2":
        print("Option 2 selected")

    elif selected_option.get() == "Option 3":
        print("Option 3 selected")


def sub_menu_widget():
    sub_menu = tk.Menu(drop_down_menu['menu'])
    sub_menu.add_command(label="Sub Option 1", command=lambda: print("Sub Option 1 selected"))
    sub_menu.add_command(label="Sub Option 2", command=lambda: print("Sub Option 2 selected"))
    sub_menu.add_command(label="Sub Option 3", command=lambda: print("Sub Option 3 selected"))
    return sub_menu


selected_option.trace("w", option_selected)

drop_down_menu = tk.OptionMenu(window, selected_option, *options)
drop_down_menu.pack()

window.mainloop()

In this example, we created a hierarchical dropdown menu. When the user selects the "Main Menu" option, we replace the existing options with a new cascade menu. The new cascade menu will contain more options that can be selected.

Conclusion

The dropdown menu is a common graphical element that any developer requires to create a user-friendly interface. In this article, we have discussed how to create a dropdown menu in tkInter using the OptionMenu method. We also learned how to set the default value for the dropdown menu, how to retrieve the selected value, and how to customize the menu. We also went into advanced features such as how to create cascading menus. By understanding this fundamental concept, you can create dynamic and interactive user interfaces in your Python applications.

Popular questions

  1. What is a dropdown menu in tkinter?
  • A dropdown menu in tkinter is a GUI element that allows users to select an option from a list of predefined items.
  1. How can you create a dropdown menu in tkinter?
  • To create a dropdown menu in tkinter, you can use the OptionMenu method. You first create a list of options, a variable to hold the selected option, and then create the dropdown menu widget using the OptionMenu method.
  1. What is the command attribute in a dropdown menu?
  • The command attribute is an optional argument for the OptionMenu method that allows you to specify a function that is called when the user selects a dropdown menu option.
  1. How can you customize a dropdown menu in tkinter?
  • You can customize a dropdown menu in tkinter by changing its background and foreground colors, changing the font and font size, and changing the width and height of the dropdown menu widget.
  1. Can you create a cascading dropdown menu in tkinter?
  • Yes, you can create a cascading dropdown menu in tkinter using the insert_cascade method of the Menu widget. A cascading menu is a hierarchical menu that expands on the selection of another option in the dropdown menu.

Tag

"DropdownTkinter"

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