How to do Django form validation

In this shot, we’ll learn to do Django form validation. Django automatically has built-in methods that validate the data from the form.

Note: Django forms are similar to advanced HTMLHyperText Markup Language forms, except that they are more Python-oriented in nature.

Code

First, install Django by using the following commands:

pip install pipenv
pipenv shell
pipenv install django

Next, create the Django project:

django-admin startproject DjangoForm ./
python manage.py startapp codebase

python manage.py migrate
python manage.py runserver

Configurations

First, add the project name to the settings.py file, as shown below:

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'codebase'
]

Note: codebase should be replaced by the name of your Django project.

Next, in the codebase application folder, go to the models.py file and create the following model:

from django.db import models
# model named Post
class CommentModel(models.Model):
	name = models.CharField( max_length = 100, blank = False,null = False)
	comment = models.TextField(blank = False, null = False)
	time = models.DateTimeField(auto_now_add = True)

Once our model is created, register it in the admin.py file, as shown below:

from django.contrib import admin
from .models import CommentModel
admin.site.register(CommentModel)

Create the form

After completing the configuration, create a file for the form. In our case, the file is named forms.py.

from logging import PlaceHolder
from django import forms
from .models import CommentModel
class CommentForm(forms.ModelForm):
    name = forms.CharField(widget=forms.TextInput(attrs={
        'class': 'form-control',
        'placeholder': 'name'
    }))
    comment = forms.CharField(widget=forms.Textarea(attrs={
        'class': 'form-control',
        'placeholder': 'comment section'
    }))
    class Meta:
        model = CommentModel
        fields = ['name', 'comment']
   
    def clean(self):
        # data is feteched using the super function of django
        super(CommentForm, self).clean()
        name  = self.cleaned_data.get('name')
        comment = self.cleaned_data.get('comment')
        if len(name) < 3:
            self._errors['name'] = self.error_class([
                '3 characters and more is required for this field'
            ])
        if len(comment) < 4:
            self._errors['comment'] = self.error_class([
                'comments should be more than 4 characters'
            ])
        return self.cleaned_data

Now, create a view for our project with the form created. The corresponding views.py file is shown below:

from django.shortcuts import render, redirect
from .models import CommentModel
from .forms import CommentForm
def home(request):
    form = CommentForm(request.POST or None)
    if request.method == 'POST':
        if form.is_valid():
            form.save()
            return redirect ('home')
    context = {
        'form': form
    }
        
    return render(request, 'app/home.html', context)
  • Next, in the codebase app folder, create a folder and name it templates.
  • Inside the templates folder, create another folder and name it app.
  • Inside the app folder, create the home.html file as shown below:
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css" rel="stylesheet" 
        integrity="sha384-1BmE4kWBq78iYhFldvKuhfTAU6auU8tT94WrHftjDbrCEXSU1oBoqyl2QvZ6jIW3"
        crossorigin="anonymous">
</head>
<body class="container mt-4">
    <form method="POST" action="">
        {% csrf_token %}
        <div class="form-group mb-3">
            
            {{form.name}}
            {{form.name.errors}}
        </div>
        <div class="form-group mb-3">
            {{form.comment}}
            {{form.comment.errors}}
        </div>
        <button class="btn btn-outline-success">Submit</button>
    </form>
    
    
    
</body>
</html>

Set route URLs

Within the main folder, in the urls.py file, add a route to the URLs of the codebase app, as shown below:

from django.contrib import admin
from django.urls import path, include
urlpatterns = [
    path('admin/', admin.site.urls),
    # including the codebase urls.py file
    path('', include('codebase.urls'))
]

Finally, in the codebase folder, create a file called urls.py that contains the route to the home view:

from django.urls import path
#importing home function from views.py
from .views import home
urlpatterns = [
    path('', home, name='home'),
]

Access form

Once the entry process is complete, run the following commands:

python manage.py makemigrations

python manage.py migrate

In case you want to create a super-user, run the following command:

python manage.py createsuperuser

Once we’re ready to access the newly created form, run this command:

python manage.py runserver

The command above starts our server on the URL: http://127.0.0.1:8000/admin, which can be accessed now.

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