Django - Tutorial 020. Adding articles pagination to the site using ListView and django-bootstrap3

Pagination, Django, django-bootstrap3, ListView

In one of the previous articles , the option of introducing a page with articles pagination was shown, which can be the main page of the site, for example. In this case, django-bootstrap3 was used.

But if the page does not represent any special functionality, in addition to displaying the list of articles, for example, then you must use the generic classes. One of which is ListView . This will reduce the program code of the project and, accordingly, simplify it.

The ListView class allows you to specify a template that will be rendered to display the table, specify a data model or queryset that will need to be shown, as well as the number of objects per page that will be displayed when paginated.

IndexView

Let's recall how the previous View of the class looked to display the list of pages.

class IndexView(View):

    def get(self, request):
        context = {}
        # Taking all of the published article, sorted by date of publication
        all_articles = Article.objects.filter(article_status=True).order_by('-article_date')
        # Create Pagination, in which we send article and show,
        # that there will be 10 pieces on one page
        current_page = Paginator(all_articles, 10)

        # Pagination in django_bootstrap3 send response in this view:
        # "GET /?page=2 HTTP/1.0" 200,
        # So you need to pick up the page and try to pass it in Paginator, to find the page
        page = request.GET.get('page')
        try:
            # If there is, then choose this page
            context['article_lists'] = current_page.page(page)  
        except PageNotAnInteger:
            # If None, then select the first page
            context['article_lists'] = current_page.page(1)  
        except EmptyPage:
            # If you have gone beyond the last page, it returns the last
            context['article_lists'] = current_page.page(current_page.num_pages) 

        return render_to_response('home/index.html', context)

If you delete all comments, you still get lines 15. In addition, this is a separate class. And if there are many such View classes, then it can happen that each will have a duplicate code. That's why you need to use generics, such as ListView.

The same class inherited from ListView might look like this:

class IndexView(ListView):
    template_name = 'home/index.html'
    queryset = Article.objects.filter(article_status=True).order_by('-article_date')
    paginate_by = 10

Quite good, only 4 lines. But you can go even further and write everything at once in the urls.py file. And from the views.py file, you can remove IndexView .

from django.conf.urls import url
from django.views.generic import ListView

from knowledge.models import Article

app_name = 'home'
urlpatterns = [
    url(r'^$',
        ListView.as_view(
            template_name='home/index.html',
            queryset=Article.objects.filter(
                article_status=True,
            ).order_by(
                '-article_date'
            ),
            paginate_by=10
        ),
        name='index'),
]

django-bootstrap3

But when creating links pagination with django-bootstrap3 there is one nuance. The matter is that in the template bootstrap_pagination takes an object of type Page. And if in the old version we passed the object to the context, then ListView generates a normal QuerySet , which is not suitable for bootstrap_pagination. But still ListView passes in the context the object page_obj , which is just suitable for bootstrap_pagination .

Let's see what the home/index.html template looks like now.

{% extends 'home/base.html' %}
{% block page %}
    <h1>Publications</h1>
    {% if article_lists %}
        {% for article in object_list %}
            <article>
                <a href="{{ article.get_absolute_url }}">
                    <h2>{{ article.article_title }}</h2>
                </a>
                {{ article.desctription|safe }}
                <p><a class="btn btn-default btn-sm" href="{{ article.get_absolute_url }}">Читать далее</a></p>
            </article>
        {% endfor %}
    {% endif %}
{% load bootstrap3 %}
{% bootstrap_pagination page_obj %}
{% endblock %}

As you can see, there are two significant changes compared to the previous version:

1. page_obj instead of article_lists в boostrap_pagination
2. object_list instead of article_lists

However, ListView has a variable context_object_name , which is responsible for the variable name in the context, so you could leave article_lists .

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