Pagination 기억 단서

텍스트:https://docs.djangoproject.com/en/1.6/topics/pagination/ 
Pagination
Django provides a few classes that help you manage paginated data – that is, data that’s split across several pages, with “Previous/Next” links. These classes live in django/core/paginator.py.
★ Django 페이지 나누기
Example
Give Paginator a list of objects, plus the number of items you’d like to have on each page, and it gives you methods for accessing the items for each page:
★ 간단한 예시, Django가 어떻게 일을 하는지 보여주기

>>> from django.core.paginator import Paginator
>>> objects = ['john', 'paul', 'george', 'ringo']
>>> p = Paginator(objects, 2)

>>> p.count
4
>>> p.num_pages
2
>>> p.page_range
[1, 2]

>>> page1 = p.page(1)
>>> page1

>>> page1.object_list
['john', 'paul']

>>> page2 = p.page(2)
>>> page2.object_list
['george', 'ringo']
>>> page2.has_next()
False
>>> page2.has_previous()
True
>>> page2.has_other_pages()
True
>>> page2.next_page_number()
Traceback (most recent call last):
...
EmptyPage: That page contains no results
>>> page2.previous_page_number()
1
>>> page2.start_index() # The 1-based index of the first item on this page
3
>>> page2.end_index() # The 1-based index of the last item on this page
4

>>> p.page(0)
Traceback (most recent call last):
...
EmptyPage: That page number is less than 1
>>> p.page(3)
Traceback (most recent call last):
...
EmptyPage: That page contains no results

Note
Note that you can give Paginator a list/tuple, a Django QuerySet, or any other object with a count() or __len__()method. When determining the number of objects contained in the passed object, Paginator will first try callingcount(), then fallback to using len() if the passed object has no count() method. This allows objects such as Django’s QuerySet to use a more efficient count() method when available.
Using Paginator in a view  
Here’s a slightly more complex example using Paginator in a view to paginate a queryset. We give both the view and the accompanying template to show how you can display the results. This example assumes you have a Contacts model that has already been imported.
★ 복잡한 예시,view와template를 통해 페이지를 나누는 방법을 보여 줍니다
The view function looks like this:

from django.core.paginator import Paginator, EmptyPage, PageNotAnInteger

def listing(request):
    contact_list = Contacts.objects.all()
    paginator = Paginator(contact_list, 25) # Show 25 contacts per page

    page = request.GET.get('page')
    try:
        contacts = paginator.page(page)
    except PageNotAnInteger:
        # If page is not an integer, deliver first page.
        contacts = paginator.page(1)
    except EmptyPage:
        # If page is out of range (e.g. 9999), deliver last page of results.
        contacts = paginator.page(paginator.num_pages)

    return render_to_response('list.html', {"contacts": contacts})

In the template list.html, you’ll want to include navigation between pages along with any interesting information from the objects themselves:

{% for contact in contacts %}
    {# Each "contact" is a Contact model object. #}
    {{ contact.full_name|upper }}

    ...
{% endfor %}


    
        {% if contacts.has_previous %}
            previous
        {% endif %}

        
            Page {{ contacts.number }} of {{ contacts.paginator.num_pages }}.
        

        {% if contacts.has_next %}
            next
        {% endif %}
    

Paginator objects
The Paginator class has this constructor:
class 
Paginator(
object_list, 
per_page, 
orphans=0, 
allow_empty_first_page=True)
Required arguments
object_list
A list, tuple, Django 
QuerySet, or other sliceable object with a 
count() or 
__len__() method.
per_page
The maximum number of items to include on a page, not including orphans (see the 
orphans optional argument below).
Optional arguments
orphans
The minimum number of items allowed on the last page, defaults to zero. Use this when you don’t want to have a last page with very few items. If the last page would normally have a number of items less than or equal to 
orphans, then those items will be added to the previous page (which becomes the last page) instead of leaving the items on a page by themselves. For example, with 23 items, 
per_page=10, and 
orphans=3, there will be two pages; the first page with 10 items and the second (and last) page with 13 items.
allow_empty_first_page
Whether or not the first page is allowed to be empty. If 
False and 
object_list is empty, then an 
EmptyPage error will be raised.
Methods
Paginator.
page(
number)
Returns a Page object with the given 1-based index. Raises InvalidPage if the given page number doesn’t exist.
Attributes
Paginator.
count
The total number of objects, across all pages.
Note
When determining the number of objects contained in object_list, Paginator will first try callingobject_list.count(). If object_list has no count() method, then Paginator will fallback to usinglen(object_list). This allows objects, such as Django’s QuerySet, to use a more efficient count() method when available.
Paginator.
num_pages
The total number of pages.
Paginator.
page_range
A 1-based range of page numbers, e.g., [1, 2, 3, 4].
InvalidPage exceptions
exception 
InvalidPage
A base class for exceptions raised when a paginator is passed an invalid page number.
The Paginator.page() method raises an exception if the requested page is invalid (i.e., not an integer) or contains no objects. Generally, it’s enough to trap the InvalidPage exception, but if you’d like more granularity, you can trap either of the following exceptions:
exception 
PageNotAnInteger
Raised when page() is given a value that isn’t an integer.
exception 
EmptyPage
Raised when page() is given a valid value but no objects exist on that page.
Both of the exceptions are subclasses of InvalidPage, so you can handle them both with a simple except InvalidPage.
Page objects
You usually won’t construct Page objects by hand – you’ll get them using Paginator.page().
class 
Page(
object_list, 
number, 
paginator)
A page acts like a sequence of Page.object_list when using len() or iterating it directly.
Methods
Page.
has_next()
Returns True if there’s a next page.
Page.
has_previous()
Returns True if there’s a previous page.
Page.
has_other_pages()
Returns True if there’s a next or previous page.
Page.
next_page_number()
Returns the next page number.
Changed in Django 1.5:
Raises InvalidPage if next page doesn’t exist.
Page.
previous_page_number()
Returns the previous page number.
Changed in Django 1.5:
Raises InvalidPage if previous page doesn’t exist.
Page.
start_index()
Returns the 1-based index of the first object on the page, relative to all of the objects in the paginator’s list. For example, when paginating a list of 5 objects with 2 objects per page, the second page’s start_index() would return 3.
Page.
end_index()
Returns the 1-based index of the last object on the page, relative to all of the objects in the paginator’s list. For example, when paginating a list of 5 objects with 2 objects per page, the second page’s end_index() would return 4.
Attributes
Page.
object_list
The list of objects on this page.
Page.
number
The 1-based page number for this page.
Page.
paginator
The associated Paginator object.