"""

30. Object pagination

Django provides a framework for paginating a list of objects in a few lines

of code. This is often useful for dividing search results or long lists of

objects into easily readable pages.

"""

from django.db import models

class Article(models.Model):

    headline = models.CharField(maxlength=100, default='Default headline')

    pub_date = models.DateTimeField()

    def __str__(self):

        return self.headline

__test__ = {'API_TESTS':"""

# prepare a list of objects for pagination

>>> from datetime import datetime

>>> for x in range(1, 10):

...     a = Article(headline='Article %s' % x, pub_date=datetime(2005, 7, 29))

...     a.save()

# create a basic paginator, 5 articles per page

>>> from django.core.paginator import ObjectPaginator, InvalidPage

>>> paginator = ObjectPaginator(Article.objects.all(), 5)

# the paginator knows how many hits and pages it contains

>>> paginator.hits

9

>>> paginator.pages

2

# get the first page (zero-based)

>>> paginator.get_page(0)

[<Article: Article 1>, <Article: Article 2>, <Article: Article 3>, <Article: Article 4>, <Article: Article 5>]

# get the second page

>>> paginator.get_page(1)

[<Article: Article 6>, <Article: Article 7>, <Article: Article 8>, <Article: Article 9>]

# does the first page have a next or previous page?

>>> paginator.has_next_page(0)

True

>>> paginator.has_previous_page(0)

False

# check the second page

>>> paginator.has_next_page(1)

False

>>> paginator.has_previous_page(1)

True

>>> paginator.first_on_page(0)

1

>>> paginator.first_on_page(1)

6

>>> paginator.last_on_page(0)

5

>>> paginator.last_on_page(1)

9

# Add a few more records to test out the orphans feature.

>>> for x in range(10, 13):

...     Article(headline="Article %s" % x, pub_date=datetime(2006, 10, 6)).save()

# With orphans set to 3 and 10 items per page, we should get all 12 items on a single page:

>>> paginator = ObjectPaginator(Article.objects.all(), 10, orphans=3)

>>> paginator.pages

1

# With orphans only set to 1, we should get two pages:

>>> paginator = ObjectPaginator(Article.objects.all(), 10, orphans=1)

>>> paginator.pages

2

"""}