How to use Regex Validator in Django? - Coding

Django, a popular web framework, provides a built-in regex validator that allows you to enforce specific patterns on input data. Whether you need to validate user input, form fields, or any other data in your Django application, regex validators can be incredibly useful. In this article, we’ll explore how to use regex validators in Django.

Setting up the Project

Installation: To install Django.

Creating the Project

Create the project by using the command:

django-admin startproject bookstore
cd bookstore

Create an application named ‘mini’ by using the command:

python manage.py startapp mini

Now add this app to the ‘INSTALLED_APPS’ in the settings file.

Structuring Your Project

Screenshot-from-2023-09-09-03-03-33

mini/models.py

This code defines a Django model called Vehicle with a registration_number field. The registration_number field is limited to a maximum length of 10 characters and is validated using a RegexValidator to ensure it follows the specified format. The ‘__str__’ method is provided to display the registration number when you print a Vehicle object.

Python3

# models.py
from django.core.validators import RegexValidator
from django.db import models
 
class Vehicle(models.Model):
    registration_number = models.CharField(
        max_length=10,
        validators=[
            RegexValidator(
                regex=r'^[A-Z]{3}\d{3}$',
                message="Enter a valid registration number in the format ABC123.",
                code="invalid_registration",
            ),
        ],
    )
 
    def __str__(self):
        return self.registration_number

mini/view.py

These views work together to allow users to add new vehicles with registration numbers following the specified format and to view a list of all vehicles in the system. The ‘add_vehicle’ view handles form submissions, including regex validation, while the vehicle_list view displays the list of vehicles stored in the database.

Python3

# views.py
from django.shortcuts import render, redirect
from .models import Vehicle
from .forms import VehicleForm
 
def add_vehicle(request):
    if request.method == 'POST':
        form = VehicleForm(request.POST)
        if form.is_valid():
            form.save()
            return redirect('vehicle_list')
    else:
        form = VehicleForm()
     
    return render(request, 'add_vehicle.html', {'form': form})
 
def vehicle_list(request):
    vehicles = Vehicle.objects.all()
    return render(request, 'vehicle_list.html', {'vehicles': vehicles})

mini/form.py

By defining VehicleForm in this manner, you are essentially creating a form that is tightly integrated with the Vehicle model.

Python3

# forms.py
from django import forms
from .models import Vehicle
 
class VehicleForm(forms.ModelForm):
    class Meta:
        model = Vehicle
        fields = ['registration_number']

templates/add_vehicle.html

This file used to add vehicle details.

HTML

<!DOCTYPE html>
<html>
<head>
    <title>Add Vehicle</title>
</head>
<body>
    <h1>Add Vehicle</h1>
    <form method="post">
        {% csrf_token %}
        {{ form.as_p }}
        <button type="submit">Save</button>
    </form>
</body>
</html>

templates/vehicle_list.html

This HTML file is used for listing the vehicles.

HTML

<!DOCTYPE html>
<html>
<head>
    <title>Vehicle List</title>
</head>
<body>
    <h1>Vehicle List</h1>
    <ul>
        {% for vehicle in vehicles %}
            <li>{{ vehicle }}</li>
        {% empty %}
            <li>No vehicles in the list.</li>
        {% endfor %}
    </ul>
    <a href="{% url 'add_vehicle' %}">Add Vehicle</a>
</body>
</html>

mini/urls.py

Configure your app’s URLs to map to the views you’ve created:

Python3

# mini/urls.py
from django.urls import path
from . import views
 
urlpatterns = [
    path('add-vehicle/', views.add_vehicle, name='add_vehicle'),
    path('vehicle-list/', views.vehicle_list, name='vehicle_list'),
]

urls.py

Include your app’s URLs in the project’s main urls.py:

Python3

# urls.py
from django.contrib import admin
from django.urls import path, include
 
urlpatterns = [
    path('admin/', admin.site.urls),
    path('vehicles/', include('your_app.urls')),
]

Output

Reffered: https://www.geeksforgeeks.org

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