Django 分页

Reference: https://simpleisbetterthancomplex.com/tutorial/2016/08/03/how-to-paginate-with-django.html

 

How to Paginate with Django

(Picture: https://unsplash.com/search/book?photo=X9GHkHbJIaU)

As part of the Django’s common Web application tools, Django offers a few classes to manage paginated data. You can pass either a list/tuple of objects or an QuerySet. In this tutorial I will show how to paginate data using function based views and how to paginate using class-based views (ListView).

---

The Paginator

The paginator classes lives in django.core.paginator. We will be working mostly with the Paginator and Page classes.

Consider the auth.User table has 53 user instances.

from django.contrib.auth.models import User
from django.core.paginator import Paginator

user_list = User.objects.all()
paginator = Paginator(user_list, 10)

In the example above I’m telling Paginator to paginate the user_listQuerySet in pages of 10. This will create a 6 pages result. The first 5 pages with 10 users each and the last page with 3 users.

Debugging the Paginator Object

Input	Output	Type
paginator.count	53	<type 'int'>
paginator.num_pages	6	<type 'int'>
paginator.page_range	xrange(1, 7)	<type 'xrange'>
paginator.page(2)	<Page 2 of 6>	<class 'django.core.paginator.Page'>

The Paginator.page() method will return a given page of the paginated results, which is an instance of Page. This is what we will return to the template.

users = paginator.page(2)

Debugging the Page Object

Input	Output	Type
users	<Page 2 of 6>	<class 'django.core.paginator.Page'>
users.has_next()	True	<type 'bool'>
users.has_previous()	True	<type 'bool'>
users.has_other_pages()	True	<type 'bool'>
users.next_page_number()	3	<type 'int'>
users.previous_page_number()	1	<type 'int'>
users.start_index()	11	<type 'int'>
users.end_index()	20	<type 'int'>

The Page.next_page_number() and Page.previous_page_number() methods raises InvalidPage if next/previous page doesn’t exist.

The Page.start_index() and Page.end_index() are relative to the page number.

>>> users = paginator.page(6)  # last page
<Page 6 of 6>
>>> users.start_index()
51
>>> users.end_index()
53

The process is basically done by querying the database, then pass the QuerySet to the Paginator, grab a Page and return to the template. The rest is done in the template.

Let’s see now some practical examples.

---

Pagination with Function-Based Views

views.py

from django.contrib.auth.models import User
from django.core.paginator import Paginator, EmptyPage, PageNotAnInteger

def index(request):
    user_list = User.objects.all()
    page = request.GET.get('page', 1)

    paginator = Paginator(user_list, 10)
    try:
        users = paginator.page(page)
    except PageNotAnInteger:
        users = paginator.page(1)
    except EmptyPage:
        users = paginator.page(paginator.num_pages)

    return render(request, 'core/user_list.html', { 'users': users })

user_list.html

<table class="table table-bordered">
  <thead>
    <tr>
      <th>Username</th>
      <th>First name</th>
      <th>Email</th>
    </tr>
  </thead>
  <tbody>
    {% for user in users %}
      <tr>
        <td>{{ user.username }}</td>
        <td>{{ user.first_name }}</td>
        <td>{{ user.email }}</td>
      </tr>
    {% endfor %}
  </tbody>
</table>

{% if users.has_other_pages %}
  <ul class="pagination">
    {% if users.has_previous %}
      <li><a href="?page={{ users.previous_page_number }}">&laquo;</a></li>
    {% else %}
      <li class="disabled"><span>&laquo;</span></li>
    {% endif %}
    {% for i in users.paginator.page_range %}
      {% if users.number == i %}
        <li class="active"><span>{{ i }} <span class="sr-only">(current)</span></span></li>
      {% else %}
        <li><a href="?page={{ i }}">{{ i }}</a></li>
      {% endif %}
    {% endfor %}
    {% if users.has_next %}
      <li><a href="?page={{ users.next_page_number }}">&raquo;</a></li>
    {% else %}
      <li class="disabled"><span>&raquo;</span></li>
    {% endif %}
  </ul>
{% endif %}

The result is something like this:

The example above is using Bootstrap 3.

---

Pagination with Class-Based Views

views.py

class UserListView(ListView):
    model = User
    template_name = 'core/user_list.html'  # Default: <app_label>/<model_name>_list.html
    context_object_name = 'users'  # Default: object_list
    paginate_by = 10
    queryset = User.objects.all()  # Default: Model.objects.all()

user_list.html

<table class="table table-bordered">
  <thead>
    <tr>
      <th>Username</th>
      <th>First name</th>
      <th>Email</th>
    </tr>
  </thead>
  <tbody>
    {% for user in users %}
      <tr>
        <td>{{ user.username }}</td>
        <td>{{ user.first_name }}</td>
        <td>{{ user.email }}</td>
      </tr>
    {% endfor %}
  </tbody>
</table>

{% if is_paginated %}
  <ul class="pagination">
    {% if page_obj.has_previous %}
      <li><a href="?page={{ page_obj.previous_page_number }}">&laquo;</a></li>
    {% else %}
      <li class="disabled"><span>&laquo;</span></li>
    {% endif %}
    {% for i in paginator.page_range %}
      {% if page_obj.number == i %}
        <li class="active"><span>{{ i }} <span class="sr-only">(current)</span></span></li>
      {% else %}
        <li><a href="?page={{ i }}">{{ i }}</a></li>
      {% endif %}
    {% endfor %}
    {% if page_obj.has_next %}
      <li><a href="?page={{ page_obj.next_page_number }}">&raquo;</a></li>
    {% else %}
      <li class="disabled"><span>&raquo;</span></li>
    {% endif %}
  </ul>
{% endif %}