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How to Use MaxLengthValidator in Django

Last Updated : 24 Apr, 2025

Django, an excessive degree Python web framework, affords a plethora of gear and capabilities to make net development simpler and extra green. One such feature is the MaxLengthValidator, a validation tool that lets you enforce man or woman limits on entering fields for your Django fashions. In this newsletter, we will discover a way to use MaxLengthValidator in Django to make sure that your information stays inside detailed duration constraints.

MaxLengthValidator in Django

Install Django and follow these steps:

Creating the Project Files

To start the project use this command

django-admin startproject microblog
cd microblog

To start the app use this command

python manage.py startapp app

Now add this app to the 'settings.py' in the installed app.

Setting up the Files

app/model.py: In this model, we have a content field with a maximum length of 14 characters, and we've added the 'MaxLengthValidator' to enforce this limit.

Python3

from django.db import models
from django.core.validators import MaxLengthValidator

class Message(models.Model):
    content = models.CharField(
        max_length=140,
        validators=[MaxLengthValidator(limit_value=14, 
                              message="Message is too long")]
    )
    created_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.content

app/form.py: It is used to create a form for adding new messages in Django forms

Python3

from django import forms
from .models import Message

class MessageForm(forms.ModelForm):
    class Meta:
        model = Message
        fields = ['content']

app/views.py: we define two views:

home: Displays existing messages in descending order of creation.
add_message: Handles adding new messages and enforces the character limit.

Python3

from django.shortcuts import render, redirect
from .models import Message
from .forms import MessageForm
def index(request):
    messages = Message.objects.all().order_by('-created_at')
    return render(request, 'myapp/index.html', {'messages': messages})

def add_message(request):
    if request.method == 'POST':
        form = MessageForm(request.POST)
        if form.is_valid():
            form.save()
            return redirect('home')
    else:
        form = MessageForm()
    return render(request, 'myapp/index2.html', {'form': form})

Creating GUI for the Project

Create a templates folder and, create 2 files, Here we named it as index.html and index2.html.

index.html: We create HTML templates for displaying messages (index.html) and adding messages (index2.html) in the templates folder.

HTML

<-- index.html -->
<!DOCTYPE html>
<html>
<head>
    <title>Microblog</title>
</head>
<body>
    <h1>Microblog</h1>
    <ul>
        {% for message in messages %}
            <li>{{ message.content }}</li>
        {% endfor %}
    </ul>
    <a href="{% url 'add_message' %}">Add Message</a>
</body>
</html>

index2.html: This HTML page is used to collect the Information from the user.

HTML

<-- index2.html -->
<!DOCTYPE html>
<html>
<head>
    <title>Add Message</title>
</head>
<body>
    <h1>Add Message</h1>
    <p>The word limit is 13</p>

    <form method="post">
        {% csrf_token %}
        {{ form.as_p }}
        <input type="submit" value="Submit">
    </form>
    <a href="{% url 'home' %}">Back to Home</a>
</body>
</html>

app/urls.py: URLs for the app are defined in app/urls.py, including the homepage and the add message page.

Python3

from django.urls import path
from . import views

urlpatterns = [
    path('', views.index, name='home'),
    path('add/', views.add_message, name='add_message'),
]

urls.py: We include the app's URLs in the project's urls.py.

Python3

from django.contrib import admin
from django.urls import path, include

urlpatterns = [
    path('admin/', admin.site.urls),
    path('', include('app.urls')),
]

Deployement of the Project

Migrate your files to the database:

python manage.py makemigrations
python manage.py migrate

Deploy your project

python manage.py runserver

Output:

Add message - maxvalidators

Screenshot-from-2023-09-28-15-05-28

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python

How to Use MaxLengthValidator in Django

MaxLengthValidator in Django

Creating the Project Files

Setting up the Files

Creating GUI for the Project

Deployement of the Project

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