How to Use MaxLengthValidator in Django
Last Updated : 28 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:
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