How django template url matching works - django

Question

I'm trying to figure out how url matching works in django template.
What i'm trying to achieve is when clicking on a link it would bring up a specific objects.
Models.py
class PostManager(models.Manager):
def get_queryset(self):
return super(PostManager,self).get_queryset().filter(status='published')
class Post(models.Model):
STATUS_CHOICES = (('published','Published'),
('draft','Draft '))
FIELD_CHOICES = (('1','1 Title and body field'),
('2','2 Title and body fields'),
('3','3 Title and body fields'),
('4', '4 Title and body fields'),
('5', '5 Title and body fields'))
author = models.ForeignKey(User,
on_delete=models.CASCADE,
related_name='blog_post')
title = models.CharField(max_length=100)
sub_title = models.TextField(max_length=50,default="")
title_1 = models.CharField(max_length=100,null=True,blank=True)
title_1_body = models.TextField(null=True,blank=True)
title_2 = models.CharField(max_length=100,null=True,blank=True)
title_2_body = models.TextField(null=True,blank=True)
title_3 = models.CharField(max_length=100,null=True,blank=True)
title_3_body = models.TextField(null=True,blank=True)
title_4 = models.CharField(max_length=100,null=True,blank=True)
title_4_body = models.TextField(null=True,blank=True)
title_5 = models.CharField(max_length=100,null=True,blank=True)
title_5_body = models.TextField(null=True,blank=True)
created = models.DateField()
publish = models.DateTimeField(default=timezone.now)
slug = models.SlugField(max_length=250,
unique_for_date='created')
status = models.CharField(max_length=250,
choices=STATUS_CHOICES,
default='draft')
object = models.Manager()
postManager = PostManager()
class Meta():
ordering = ('publish',)
def __str__(self):
return self.title
def get_absolute_url(self):
return reverse('post_detail',
args=[self.slug])
def get_image_filename(instance, filename):
title = Post.title
slug = slugify(title)
return "media/%s-%s" % (slug, filename)
class Image(models.Model):
post = models.ForeignKey(Post,
on_delete=models.CASCADE,
related_name='images')
image_1 = models.ImageField(upload_to=get_image_filename,default='123.jpg',verbose_name="Image",null=True)
image_2 = models.ImageField(upload_to=get_image_filename,default='123.jpg',verbose_name="Image",null=True)
image_3 = models.ImageField(upload_to=get_image_filename,default='123.jpg',verbose_name="Image",null=True)
image_4 = models.ImageField(upload_to=get_image_filename,default='123.jpg',verbose_name="Image",null=True)
image_5 = models.ImageField(upload_to=get_image_filename,default='123.jpg',verbose_name="Image",null=True)
views.py
def post_detail(request):
post = get_object_or_404(Post)
return render(request, 'blog_application/templates/single.html',
{'post':post})
index.html
{% for elem in posts %}
<p class="mb-md-5">A small river named Duden flows by their place and supplies it with the necessary regelialia</p>
<p>Read More <span class="icon-arrow_forward ml-lg-4"></span></p>
{% endfor %}
urls.py
path('post_detail/<slug:slug>',views.post_detail,name='single'),
path('', views.show_index, name='index'),
I don't quite understand how url matching and linking works for templates. Could some one be kind enough to explain based on my example.

Answer 1

There's two issues in your view:
def post_detail(request, slug):
post = get_object_or_404(Post, slug=slug)
return render(request, 'blog_application/templates/single.html',
{'post':post})
on a more general note, you receive the slug value from the url and pass it to your view with the argument.
Also, you need to pass the argument to get_object_or_404 see this.

Answer 2

before I dive, Let's agree that a slug is just a fancy name, It's just a string nothing else.
Ok so you want to understand how django urls work. back off plz
Let's first understand how URLs work, let's say I'll open this website www.example.com & just open it as is, The website just opens right? You expect the home page to be there
Now, let's open it as www.example.com?text=welcome
Press F12 in chrome & switch to networks tab, Essentially what happens is that you added a parameter which appears in chrome as 'query string parameter' at the very bottom of the networks tab, This says you wanted to visit this website with a parameter called text that contains the string hello
Ok, now what's the relation between this & the question? bear with me please
Imagine I have a social website with posts & I want to create a code "slug" for each post so that when It's typed as a parameter in the URL, It gets that specific post
now, this is your urlpatterns.py
path('post_detail/<slug:slug>', views.post_detail, name='single'),
path('', views.show_index, name='index'),
I'll assume that this is the project level urls.py for simplicity.
The user visits the website without any url params or subpages, it just calls your views.show_index
now the user visits your website/post_detail/, What happens is sees if there's any urlpattern in urlpatterns that matches this, but it doesn't, so it's just a 404
now the user visits your website/post_detail/ANY_RANDOM_TEXT
What happens is that there's actually a urlpattern that matches website/post_detail/ANY_RANDOM_TEXT
which path('post_detail/<slug:slug>', views.post_detail, name='single')
therefore, the "ANY_RANDOM_TEXT" must be the slug, Let's take it as the slug then!
now we have the slug, and the urlpattern will call views.post_detail (function or view) and pass the slug to it, so we must accept it right?
def post_detail(request, slug):
post = get_object_or_404(Post, slug=slug)
return render(request, 'blog_application/templates/single.html',
{'post':post})
now you have access to the 'slug' which is just "ANY_RANDOM_TEXT" because we matched it, now get the post with slug that's the same as the slug in the url & just render it!
Btw don't forget the slash at the end of any urlpattern or otherwise the world is gonna explode