Entry Field Validation in Tkinter Python

In this article, you will learn about the entry field validation using the Tkinter Python.

Tkinter is a standard cross-platform package for creating graphical user interfaces (GUIs). This creates a window for your entire GUI application. This windowing object can contain different widgets, like- text labels, buttons, radio buttons, etc. If you want to know more about the Tkinter in detail, please click on the following link-

Python Tkinter Overview and Examples

Import Tkinter and create object

First, we need to import the Tkinter module and create a top level object using the Tk class.

from tkinter import *
root = Tk()

Install and Import Pmw

Pmw (Python Mega Widget) is a toolkit for building high-level compound widgets and mega widgets. It provides a convenient way to add functionality to a Tkinter application. If you do not have this module installed, open the terminal window and run the following command-

(env) c:\python37\Scripts\projects>pip install Pmw

On successful installation, it returns something like this-

(env) c:\python37\Scripts\projects>pip install Pmw
Successfully built Pmw
Installing collected packages: Pmw
Successfully installed Pmw-2.0.1

Next, we will import and initialise this module-

import Pmw
Pmw.initialise()

Entry Fields Validation

Python provides a standard Entry widget to enter or display a single line of text. Here is a simple example of the EntryField widget without validation.

f1 = Pmw.EntryField(root, labelpos=W, label_text='Enter Text',
        validate = None)

The above code creates a text entry field without any validation.

Python validate the Real Integer

Here, we are validating the real input. It accepts input only in the range between 96.0 to 107.0.

realno = Pmw.EntryField(root, labelpos=W, value = '98.5',
                label_text = 'Real (96.0 to 107.0):',
                validate = {'validator' : 'real',
                'min' : 96, 'max' : 107, 'minstrict' : 0})

Python validate the Integer

The below code validates the integer input. The entry field accepts an integer value only in the range between 10 and 40.

int_val = Pmw.EntryField(root, labelpos=W, label_text = 'Integer (10 to 40):',
                validate = {'validator' : 'numeric',
                'min' : 10, 'max' : 40, 'minstrict' : 0},
                value = '15')

Python validate the Date input

The below code validates the date input. It only accepts the date of the year 2019.

date_val = Pmw.EntryField(root, labelpos=W, label_text = 'Enter Date (In 2019)',
                value = '2019/01/10', validate = {'validator' : 'date',
                'min' : '2019/01/01', 'max' : '2019/12/31'})

Complete Code

Here, we have merged all the above code and run it on a terminal window.

from tkinter import *
import Pmw
root = Tk()
Pmw.initialise()


val_non = Pmw.EntryField(root, labelpos=W, label_text='Enter text',
        validate = None)
realno_val = Pmw.EntryField(root, labelpos=W, value = '98.5',
                label_text = 'Enter Real (96-107)',
                validate = {'validator' : 'real',
                'min' : 96, 'max' : 107, 'minstrict' : 0})

int_val = Pmw.EntryField(root, labelpos=W, label_text = 'Enter Integer (10-40)',
                validate = {'validator' : 'numeric',
                'min' : 10, 'max' : 40, 'minstrict' : 0},
                value = '15')
date_val = Pmw.EntryField(root, labelpos=W,label_text = 'Enter Date',
                value = '2019/01/10', validate = {'validator' : 'date',
                'min' : '2019/01/01', 'max' : '2019/12/31'})

widgets = (val_non, realno_val, int_val, date_val)
for widget in widgets:
    widget.pack(fill=X, expand=1, padx=10, pady=5)
    
Pmw.alignlabels(widgets)
real.component('entry').focus_set()
root.mainloop()

When you learn the above code, it returns the following output-

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