Tkinter Combobox: Values, get(), set(), current() and Events

A Tkinter ttk.Combobox combines an Entry field with a drop-down list. The user can select one of the predefined values and, in the default normal state, can also type a value that is not in the list.

Create a Tkinter Combobox 🔝

Combobox belongs to the tkinter.ttk module.

import tkinter as tkfrom tkinter import ttkroot=tk.Tk()root.geometry('300x150')root.title('plus2net.com')months=['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun']combo=ttk.Combobox(root, values=months, width=10)combo.grid(row=0, column=0, padx=20, pady=30)root.mainloop()

Trying to create:

tk.Combobox()

raises an error because Combobox is not part of the classic tkinter widget set.

AttributeError: module 'tkinter' has no attribute 'Combobox'

Add Options with the values Parameter 🔝

The values option contains the choices displayed in the drop-down list.

languages=['Python', 'PHP', 'JavaScript', 'SQL']combo=ttk.Combobox(root, values=languages)

A tuple can also be used:

languages=('Python', 'PHP', 'JavaScript', 'SQL')

Read the Configured Values

print(combo['values'])

The returned collection represents the options currently assigned to the Combobox.

Set a Default Combobox Value 🔝

There are two common ways to set the initial selection.

Use set()

combo.set('Apr')

Use current(index)

combo.current(3)

Combobox indexes start at zero, so index 3 represents the fourth item.

0  Jan1  Feb2  Mar3  Apr

Combobox get(), set() and current() 🔝

Read Selected Value and Index

import tkinter as tkfrom tkinter import ttkdef show_value():    result.config(text=f'{combo.get()} : index {combo.current()}')root=tk.Tk()root.geometry('380x150')months=['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun']combo=ttk.Combobox(root, values=months, width=8)combo.grid(row=0, column=0, padx=10, pady=25)combo.current(3)tk.Button(root, text='Read', command=show_value).grid(row=0, column=1)result=tk.Label(root, text='')result.grid(row=0, column=2, padx=10)root.mainloop()

If April is selected:

Apr : index 3

normal vs readonly Combobox 🔝

The default state is normal. In this state, the user can either choose a listed value or type another value manually.

combo=ttk.Combobox(root, values=months, state='normal')

Use readonly when the user must select only one of the predefined values.

combo=ttk.Combobox(root, values=months, state='readonly')

Handle Selection with <<ComboboxSelected>> 🔝

A Combobox generates the virtual event <<ComboboxSelected>> when the user selects an item from its dropdown list.

import tkinter as tkfrom tkinter import ttkdef selected(event):    label.config(text=f'Selected: {combo.get()}')root=tk.Tk()months=['Jan', 'Feb', 'Mar', 'Apr']combo=ttk.Combobox(root, values=months, state='readonly')combo.pack(padx=20, pady=20)combo.bind('<<ComboboxSelected>>', selected)label=tk.Label(root, text='Select a month')label.pack(pady=10)root.mainloop()

The callback receives an event object because it is called through bind().

Combobox with StringVar and trace_add() 🔝

A StringVar can be connected through textvariable.

import tkinter as tkfrom tkinter import ttkdef changed(*args):    label.config(text=value.get())root=tk.Tk()value=tk.StringVar()combo=ttk.Combobox(root, values=['Jan', 'Feb', 'Mar'], textvariable=value)combo.pack(pady=15)label=tk.Label(root, text='')label.pack()value.trace_add('write', changed)root.mainloop()

trace_add() vs ComboboxSelected

For most dropdown-selection logic, <<ComboboxSelected>> communicates the intention more clearly. Use trace_add() when other changes to the associated variable must also be observed.

Change Label Color from Combobox Selection 🔝

import tkinter as tkfrom tkinter import ttkdef update_color(event):    color=combo.get()    label.config(text=color, bg=color)root=tk.Tk()root.geometry('400x150')colors=['red', 'green', 'blue', 'yellow', 'lightgreen']combo=ttk.Combobox(root, values=colors, width=10, state='readonly')combo.grid(row=0, column=0, padx=10, pady=30)combo.bind('<<ComboboxSelected>>', update_color)label=tk.Label(root, text='Select a color', width=15)label.grid(row=0, column=1, padx=10)root.mainloop()

Clear a Combobox Selection 🔝

The clearest way to remove the displayed value is:

combo.set('')

Because a Combobox inherits Entry behaviour, the editable text can also be deleted with Entry methods in suitable states:

combo.delete(0, tk.END)

For normal application code, set('') more clearly expresses the intention of clearing the Combobox value.

Add Combobox Options Dynamically 🔝

The current values can be copied to a list, updated and assigned back to the Combobox.

def add_option():    new_value=entry.get().strip()    if new_value:        values=list(combo['values'])        values.append(new_value)        combo['values']=values        combo.set(new_value)        entry.delete(0, tk.END)

Complete Example

import tkinter as tkfrom tkinter import ttkdef add_option():    new_value=entry.get().strip()    if new_value:        values=list(combo['values'])        values.append(new_value)        combo['values']=values        combo.set(new_value)        entry.delete(0, tk.END)root=tk.Tk()root.geometry('450x180')combo=ttk.Combobox(root, values=['Jan', 'Feb', 'Mar'], width=10)combo.grid(row=0, column=0, padx=10, pady=30)entry=tk.Entry(root, width=12)entry.grid(row=0, column=1)tk.Button(root, text='Add', command=add_option).grid(row=0, column=2, padx=10)root.mainloop()

Prevent Duplicate Combobox Options 🔝

Check the existing values before appending a new option.

def add_option():    new_value=entry.get().strip()    values=list(combo['values'])    if new_value and new_value not in values:        values.append(new_value)        combo['values']=values        combo.set(new_value)    entry.delete(0, tk.END)

Case-Insensitive Duplicate Check

If Python and python should be considered duplicates:

def add_option():    new_value=entry.get().strip()    values=list(combo['values'])    existing={value.casefold() for value in values}    if new_value and new_value.casefold() not in existing:        values.append(new_value)        combo['values']=values

Remove the Selected Combobox Option 🔝

Removing the displayed text is different from removing an option from the values list. To prevent an option from appearing again, update values.

def remove_selected():    selected=combo.get()    values=list(combo['values'])    if selected in values:        values.remove(selected)        combo['values']=values    combo.set('')

Allow Values Outside the Combobox List 🔝

In the default normal state, the Combobox text field is editable. The user can type a value that is not in values.

import tkinter as tkfrom tkinter import ttkdef read_value():    label.config(text=f'Value: {combo.get()} | Index: {combo.current()}')root=tk.Tk()months=['Jan', 'Feb', 'Mar']combo=ttk.Combobox(root, values=months, state='normal')combo.grid(row=0, column=0, padx=10, pady=20)tk.Button(root, text='Read', command=read_value).grid(row=0, column=1)label=tk.Label(root, text='')label.grid(row=1, column=0, columnspan=2)root.mainloop()

If the user types:

Nov

and Nov is not in the configured values:

combo.get()      # 'Nov'combo.current()  # -1

Display Dictionary Values and Return Numeric Keys 🔝

A dictionary can store an internal numeric key while the Combobox displays readable names.

import tkinter as tkfrom tkinter import ttkmonths={    1: 'Jan',    2: 'Feb',    3: 'March',    4: 'April',    5: 'May'}key_by_name={name:key for key, name in months.items()}def selected(event):    name=combo.get()    month_name.config(text=name)    month_number.config(text=key_by_name[name])root=tk.Tk()combo=ttk.Combobox(root, values=list(months.values()), state='readonly', width=10)combo.grid(row=0, column=0, padx=10, pady=20)combo.bind('<<ComboboxSelected>>', selected)month_name=tk.Label(root, text='Month')month_name.grid(row=0, column=1, padx=10)month_number=tk.Label(root, text='Number')month_number.grid(row=0, column=2, padx=10)root.mainloop()

This reverse dictionary approach is efficient when each displayed value is unique.

Combobox with String Dictionary Keys 🔝

If the dictionary keys are the values shown to the user, the selected key can be used directly.

import tkinter as tkfrom tkinter import ttkgrades={'A':5, 'B':4, 'C':3, 'D':2, 'E':1, 'F':0}def selected(event):    grade=combo.get()    result.config(text=f'Grade {grade} = {grades[grade]}')root=tk.Tk()combo=ttk.Combobox(root, values=list(grades.keys()), state='readonly', width=6)combo.grid(row=0, column=0, padx=15, pady=20)combo.bind('<<ComboboxSelected>>', selected)result=tk.Label(root, text='Select a grade')result.grid(row=0, column=1)root.mainloop()

Display Product Details from a Dictionary 🔝

import tkinter as tkfrom tkinter import ttkproducts={    'item 1': ['I-1', 'Medium', 40],    'item 2': ['I-2', 'High', 60],    'item 3': ['I-3', 'Low', 20],    'item 4': ['I-4', 'Best', 70]}def selected(event):    product=combo.get()    details=', '.join(map(str, products[product]))    product_label.config(text=product)    details_label.config(text=details)root=tk.Tk()root.geometry('500x150')combo=ttk.Combobox(root, values=list(products), state='readonly', width=10)combo.grid(row=0, column=0, padx=10, pady=25)combo.bind('<<ComboboxSelected>>', selected)product_label=tk.Label(root, text='Product')product_label.grid(row=0, column=1, padx=10)details_label=tk.Label(root, text='Details')details_label.grid(row=0, column=2, padx=10)root.mainloop()

Enable, Disable or Make the Combobox Readonly 🔝

The Combobox state configuration option supports these three values:

Change the State

combo.configure(state='disabled')combo.configure(state='normal')combo.configure(state='readonly')

Enable or Disable with Radiobuttons

import tkinter as tkfrom tkinter import ttkdef change_state():    if enabled.get():        combo.configure(state='readonly')    else:        combo.configure(state='disabled')root=tk.Tk()enabled=tk.BooleanVar(value=True)months=['Jan', 'Feb', 'Mar']combo=ttk.Combobox(root, values=months, state='readonly')combo.grid(row=0, column=0, padx=10, pady=20)tk.Radiobutton(root, text='Enable', variable=enabled, value=True, command=change_state).grid(row=0, column=1)tk.Radiobutton(root, text='Disable', variable=enabled, value=False, command=change_state).grid(row=0, column=2)root.mainloop()

Refresh Values with postcommand 🔝

The postcommand callback runs immediately before the dropdown list is displayed. This is useful when the available options may have changed.

import tkinter as tkfrom tkinter import ttklanguages=['Python', 'PHP']def refresh_values():    combo['values']=languagesdef add_language():    languages.append('SQL')root=tk.Tk()combo=ttk.Combobox(root, values=languages, postcommand=refresh_values)combo.pack(pady=20)tk.Button(root, text='Add SQL', command=add_language).pack()root.mainloop()

After SQL is added, opening the dropdown calls refresh_values() and displays the latest values.

Style a ttk.Combobox 🔝

A Combobox is a themed ttk widget, so appearance should normally be controlled with ttk.Style rather than classic Tk options such as bg.

import tkinter as tkfrom tkinter import ttkroot=tk.Tk()style=ttk.Style()style.configure('My.TCombobox', font=('Arial', 14), padding=5)combo=ttk.Combobox(root, values=['Python', 'PHP', 'SQL'], style='My.TCombobox')combo.pack(padx=20, pady=20)root.mainloop()

The exact appearance of ttk widgets depends on the active operating-system/theme combination. Some colors are controlled by the selected ttk theme and may not respond identically on every platform.

Check Available Themes

print(style.theme_names())

Important ttk.Combobox Options 🔝

Display the Current Configuration

for option in combo.configure():    print(option, ':', combo.cget(option))

Use External Data as Combobox Options 🔝

The values list does not have to be written directly in the program. It can be generated from a database, CSV file, JSON data, Google Sheet or another data source.

Google Sheets data can be read with the existing Plus2net pygsheets tutorial and then assigned to the Combobox values option.

Combobox Options from Google Sheets »

Common Tkinter Combobox Mistakes 🔝

1. Using tk.Combobox()

Incorrect:

combo=tk.Combobox(root)

Correct:

from tkinter import ttkcombo=ttk.Combobox(root)

2. Assuming current() Always Returns a Valid Index

A typed value may not be in the configured values.

index=combo.current()if index == -1:    print('Current value is not in the dropdown list.')

3. Allowing Arbitrary Input When Only Listed Values Are Valid

Use:

state='readonly'

for controlled selections.

4. Using active as the Combobox state Option

Use only:

'normal''readonly''disabled'

for the Combobox state configuration option.

5. Using trace_add() When Only User Dropdown Selection Matters

Use:

combo.bind('<<ComboboxSelected>>', callback)

when the code should run specifically after the user chooses an item.

6. Clearing the Text but Not Removing the Option

This:

combo.set('')

only clears the current value. It does not remove anything from combo['values'].

7. Removing Values from the Returned Collection Directly

Create a mutable list first:

values=list(combo['values'])values.remove(selected)combo['values']=values

8. Styling ttk.Combobox Like a Classic Tk Widget

Prefer ttk.Style. Ttk appearance is theme-aware, so classic options such as arbitrary widget background colors do not behave the same way.

9. Assuming the Selection Event Fires after set()

<<ComboboxSelected>> represents user selection from the dropdown. A programmatic call such as:

combo.set('Apr')

should not be relied on to generate that user-selection event. If programmatic changes also need monitoring, a linked StringVar with trace_add() is more suitable.

Common Questions about Tkinter Combobox 🔝

How do I get the selected Combobox value?

value=combo.get()

How do I get the selected index?

index=combo.current()

The result is -1 if the current text is not one of the listed values.

How do I select an item by index?

combo.current(2)

How do I set a value directly?

combo.set('Python')

How do I prevent the user from typing another value?

combo.configure(state='readonly')

How do I detect a user selection?

combo.bind('<<ComboboxSelected>>', selected)

How do I add another dropdown option?

values=list(combo['values'])values.append('New Value')combo['values']=values

How do I clear the current selection?

combo.set('')

Summary of Tkinter ttk.Combobox 🔝

• ttk.Combobox combines an Entry field with a dropdown list.
• Import it from tkinter.ttk.
• Use values to provide dropdown choices.
• Use get() to read the current displayed value.
• Use set(value) to assign a value programmatically.
• Use current(index) to select an option by index.
• Use current() to read the current option index.
• current() returns -1 when the current value is not in values.
• The default normal state lets users type values outside the list.
• Use readonly when users should select only predefined options.
• Use disabled to prevent interaction.
• The Combobox state option uses normal, readonly or disabled.
• Use <<ComboboxSelected>> to detect user dropdown selection.
• Use StringVar.trace_add() when programmatic variable changes must also be detected.
• Use set('') to clear the current value.
• Changing the displayed value does not automatically remove an item from values.
• Convert existing values to a list before dynamically adding or removing options.
• postcommand can refresh dropdown values immediately before the list opens.
• Dictionaries are useful for displaying readable labels while retaining IDs or related data.
• Use ttk.Style for theme-aware Combobox styling.
• Combobox values can come from databases, CSV, JSON, Google Sheets or other data sources.