Dynamic data in templates

We have different pieces in place: the Post model is defined in models.py, we have post_list in views.py and the template added. But how will we actually make our posts appear in our HTML template? Because that is what we want to do – take some content (models saved in the database) and display it nicely in our template, right?

This is exactly what views are supposed to do: connect models and templates. In our post_list view we will need to take the models we want to display and pass them to the template. In a view we decide what (model) will be displayed in a template.

OK, so how will we achieve this?

We need to open our blog/views.py in our code editor. So far post_list view looks like this:

blog/views.py

from django.shortcuts import render

def post_list(request):
    return render(request, 'blog/post_list.html', {})

Remember when we talked about including code written in different files? Now is the moment when we have to include the model we have written in models.py. We will add the line from .models import Post like this:

blog/views.py

from django.shortcuts import render
from .models import Post

The dot before models means current directory or current application. Both views.py and models.py are in the same directory. This means we can use . and the name of the file (without .py). Then we import the name of the model (Post).

But what's next? To take actual blog posts from the Post model we need something called QuerySet.

QuerySet

You should already be familiar with how QuerySets work. We talked about them in Django ORM (QuerySets) chapter.

So now we want published blog posts sorted by published_date, right? We already did that in QuerySets chapter!

blog/views.py

Post.objects.filter(published_date__lte=timezone.now()).order_by('published_date')

So, let's open the blog/views.py file in the code editor, and add this piece of code to the function def post_list(request) -- but don't forget to first add from django.utils import timezone:

blog/views.py

from django.shortcuts import render
from django.utils import timezone
from .models import Post

def post_list(request):
    posts = Post.objects.filter(published_date__lte=timezone.now()).order_by('published_date')
    return render(request, 'blog/post_list.html', {})

To display our QuerySet on our blog's post list, we have two things left to do:

1. Pass the posts QuerySet to the template context, by changing the render function call. We'll do this now.
2. Modify the template to display the posts QuerySet. We'll cover this in a later chapter.

Please note that we create a variable for our QuerySet: posts. Treat this as the name of our QuerySet. From now on we can refer to it by this name.

In the render function we have one parameter request (everything we receive from the user via the Internet) and another giving the template file ('blog/post_list.html'). The last parameter, {}, is a place in which we can add some things for the template to use. We need to give them names (we will stick to 'posts' right now). :) It should look like this: {'posts': posts}. Please note that the part before : is a string; you need to wrap it with quotes: ''.

So finally our blog/views.py file should look like this:

blog/views.py

from django.shortcuts import render
from django.utils import timezone
from .models import Post

def post_list(request):
    posts = Post.objects.filter(published_date__lte=timezone.now()).order_by('published_date')
    return render(request, 'blog/post_list.html', {'posts': posts})

That's it! Time to go back to our template and display this QuerySet!

Want to read a little bit more about QuerySets in Django? You should look here: https://docs.djangoproject.com/en/3.2/ref/models/querysets/