Add the slug field inside Django Model

The slug field within Django models is a pivotal step for improving the structure and readability of URLs in web applications. This addition allows developers to automatically generate URL-friendly slugs based on titles, enhancing user experience and search engine optimization (SEO). By implementing this feature, you can create cleaner, more meaningful, and SEO-friendly URLs for your content, which is essential for attracting and retaining website visitors.

Slug field in Django

Let’s assume our blog has a post with the title ‘The Django book by Geeksforgeeks’ with primary key id= 2. We might refer to this post with 

www.geeksforgeeks.org/posts/2. 

Or, we can reference the title like

 www.geeksforgeeks.org/posts/The Django book by Geeksforgeeks. 

But the problem is spaces are not valid in URLs, they need to be replaced by %20 which is ugly, making it the following 

www.geeksforgeeks.org/posts/The%20Django%20book%20by%20geeksforgeeks 

But it is not solving meaningful URL. Another option can be

 www.geeksforgeeks.org/posts/the-django-book-by-geeksforgeeks

So, the slug is now the-django-book-by-geeksforgeeks. All letters are down cased and spaces are replaced by hyphens -

Adding Slug field in Django Models

The slug field, represented as models.SlugField in Django models, is used to store a URL-friendly version of a text-based field, such as a title. Its primary purpose is to create cleaner, more readable, and search engine-friendly URLs for your content.

STATUS_CHOICES = (
('draft', 'Draft'),
('published', 'Published'),
)

class Post(models.Model):
title = models.CharField(max_length = 250)
slug = models.SlugField(max_length = 250, null = True, blank = True)
text = models.TextField()
published_at = models.DateTimeField(auto_now_add = True)
updated = models.DateTimeField(auto_now = True)

status = models.CharField(max_length = 10, choices = STATUS_CHOICES,
                                                    default ='draft')


class Meta:
    ordering = ('-published_at', )

def __str__(self):
    return self.title

Adding Slugify to our Project

Now we need to find a way to convert the title into a slug automatically. We want this script to be triggered every time a new instance of Post model is created. For this purpose, we will use signals.

Note: Add new file util.py in the same directory where settings.py file is saved. 

import string, random
from django.db.models.signals import pre_save
from django.dispatch import receiver
from django.utils.text import slugify

def random_string_generator(size = 10, chars = string.ascii_lowercase + string.digits):
    return ''.join(random.choice(chars) for _ in range(size))

def unique_slug_generator(instance, new_slug = None):
    if new_slug is not None:
        slug = new_slug
    else:
        slug = slugify(instance.title)
    Klass = instance.__class__
    max_length = Klass._meta.get_field('slug').max_length
    slug = slug[:max_length]
    qs_exists = Klass.objects.filter(slug = slug).exists()
    
    if qs_exists:
        new_slug = "{slug}-{randstr}".format(
            slug = slug[:max_length-5], randstr = random_string_generator(size = 4))
            
        return unique_slug_generator(instance, new_slug = new_slug)
    return slug

Signals in Django

In many cases when there is a modification in a model’s instance we need to execute some action. Django provides us with an elegant way to handle these situations. The signals are utilities that allow associating events with actions. We can develop a function that will run when a signal calls it. 

In models.py file of posts app where Post Model was defined, add this in the same file: 

@receiver(pre_save, sender=Post)
def pre_save_receiver(sender, instance, *args, **kwargs):
   if not instance.slug:
       instance.slug = unique_slug_generator(instance)

The pre_save_receiver function should be placed separately outside the Post model.

Modify URL with Slug

To modify your urls.py file to use the slug field in your Django model for generating URLs, you can create URL patterns that include the slug as a parameter. Here's an example of how to do this:

from django.urls import path
from . import views

urlpatterns = [
    path('posts/<slug:slug>/', views.post_detail, name='post_detail'),
    # Other URL patterns
]

Modify Views

This `detail` view function in Django takes a `slug` parameter from the URL and searches for a post with a matching slug in a case-insensitive manner. If a post is found, it retrieves and renders the post's details using the 'details.html' template. If no matching post is found, it returns an "Post Not Found" response to inform users of the absence of the requested content.

Note: In urls.py edit detail path with path('posts/', detail). In views.py edit the detail function with 

def detail(request, slug):
    # Filter posts based on the slug (case-insensitive)
    q = Post.objects.filter(slug__iexact=slug)

    if q.exists():
        # If a post with the given slug exists, retrieve the first matching post
        q = q.first()
    else:
        # If no post is found, return an "Post Not Found" response
        return HttpResponse('<h1>Post Not Found</h1>')

    # Create a context dictionary containing the retrieved post
    context = {'post': q}

    # Render the 'details.html' template with the context
    return render(request, 'posts/details.html', context)

The last step is to add the link in HTML file <a href=”/posts/{{ a.slug }}” class=”btn btn-primary”>View</a>. Now we are ready to go to 127.0.0.1:8000/posts/title-you-have-added and it will show you the page details.html.