import math
from django.core.paginator import \
ObjectPaginator as DjangoPaginator,\
InvalidPage
from django.http import Http404
class Paginator(object):
"""
Much like Django's ``ObjectPaginator`` (which it uses), but always
represents a specific current page instead of just providing an interface
to the data. Based on the active page it makes a number of properties
available which mostly work exactly like the context that the
``object_list`` generic view provides.
``__init__`` takes the same arguments as ``ObjectPaginator``, plus an
additional parameter ``page`` to initialize the active page number. It does
not need to be an int, i.e. it can come directly from ``request.GET``; if
conversion to an integer fails, a ``Http404`` exception is raised.
You can also later assign to to ``page`` attribute.
>>> items = range(1,6789)
>>> paginator = Paginator(items, num_per_page=10, page=3)
>>> paginator.items
[21, 22, 23, 24, 25, 26, 27, 28, 29, 30]
>>> paginator.is_paginated
True
>>> paginator.results_per_page
10
>>> paginator.has_next
True
>>> paginator.has_previous
True
>>> paginator.page
3
>>> paginator.page0
2
>>> paginator.next
4
>>> paginator.previous
2
>>> paginator.last_on_page
30
>>> paginator.first_on_page
21
>>> paginator.pages
679
>>> paginator.hits
6788
"""
def __init__(self, *args, **kwargs):
page = kwargs.pop('page', 1)
self._paginator = DjangoPaginator(*args, **kwargs)
# Resolve the page number; this is similar to what the Django
# ``object_list`` generic view is doing.
try:
self.page = int(page)
except ValueError:
if page == 'last': self.page = self._paginator.pages
else: raise Http404
def _set_page(self, new_page):
self.__page = new_page
try:
self.object_list = self._paginator.get_page(new_page-1)
except InvalidPage:
if new_page != -1: raise Http404
else: self.object_list = [] # allow empty
self.items = self.object_list # alias
# update all exposed info for the new page number
self.update_attrs()
def _get_page(self): return self.__page
page = property(_get_page, _set_page)
def update_attrs(self):
"""Override in descendants to set custom fields."""
self.page0 = self.page-1
self.is_paginated = self._paginator.pages > 1
self.results_per_page = self._paginator.num_per_page
self.has_next = self._paginator.has_next_page(self.page-1)
self.has_previous = self._paginator.has_previous_page(self.page-1)
self.next = self.page+1
self.previous = self.page-1
self.last_on_page = self._paginator.last_on_page(self.page-1)
self.first_on_page = self._paginator.first_on_page(self.page-1)
self.pages = self._paginator.pages
self.hits = self._paginator.hits
self.page_range = self._paginator.page_range
class DiggPaginator(Paginator):
"""
Adds attributes to enable Digg-style formatting, with a leading block of
pages, an optional middle block, and another block at the end of the page
range. They are available as attributes, to be used in the same manner
as the default:
{% for page in paginator.leading_range %} ...
{% for page in paginator.main_range %} ...
{% for page in paginator.trailing_range %} ...
Additionally, ``page_range`` contains a nun-numeric ``False`` element
for every transition between two ranges.
{% for page in paginator.page_range %}
{% if not page %} ...
{% else %}{{ page }}
{% endif %}
{% endfor %}
Additional arguments passed to the constructor allow customization of
how those bocks are constructed:
body=5, tail=2
[1] 2 3 4 5 ... 91 92
|_________| |___|
body tail
|_____|
margin
body=5, tail=2, padding=2
1 2 ... 6 7 [8] 9 10 ... 91 92
|_| |__|
^padding^
|_| |__________| |___|
tail body tail
``margin`` is the minimum number of pages required between two ranges; if
there are less, they are combined into one.
# odd body length
>>> print DiggPaginator(range(1,1000), 10, body=5, page=1)
1 2 3 4 5 ... 99 100
>>> print DiggPaginator(range(1,1000), 10, body=5, page=100)
1 2 ... 96 97 98 99 100
# even body length
>>> print DiggPaginator(range(1,1000), 10, body=6, page=1)
1 2 3 4 5 6 ... 99 100
>>> print DiggPaginator(range(1,1000), 10, body=6, page=100)
1 2 ... 95 96 97 98 99 100
# leading range and main range are combined when close; note how
# we have varying body and padding values, and their effect.
>>> print DiggPaginator(range(1,1000), 10, body=5, padding=2, margin=2, page=3)
1 2 3 4 5 ... 99 100
>>> print DiggPaginator(range(1,1000), 10, body=6, padding=2, margin=2, page=4)
1 2 3 4 5 6 ... 99 100
>>> print DiggPaginator(range(1,1000), 10, body=5, padding=1, margin=2, page=6)
1 2 3 4 5 6 7 ... 99 100
>>> print DiggPaginator(range(1,1000), 10, body=5, padding=2, margin=2, page=7)
1 2 ... 5 6 7 8 9 ... 99 100
>>> print DiggPaginator(range(1,1000), 10, body=5, padding=1, margin=2, page=7)
1 2 ... 5 6 7 8 9 ... 99 100
# the trailing range works the same
>>> print DiggPaginator(range(1,1000), 10, body=5, padding=2, margin=2, page=98)
1 2 ... 96 97 98 99 100
>>> print DiggPaginator(range(1,1000), 10, body=6, padding=2, margin=2, page=97)
1 2 ... 95 96 97 98 99 100
>>> print DiggPaginator(range(1,1000), 10, body=5, padding=1, margin=2, page=95)
1 2 ... 94 95 96 97 98 99 100
>>> print DiggPaginator(range(1,1000), 10, body=5, padding=2, margin=2, page=94)
1 2 ... 92 93 94 95 96 ... 99 100
>>> print DiggPaginator(range(1,1000), 10, body=5, padding=1, margin=2, page=94)
1 2 ... 92 93 94 95 96 ... 99 100
# all three ranges may be combined as well
>>> print DiggPaginator(range(1,151), 10, body=6, padding=2, page=7)
1 2 3 4 5 6 7 8 9 ... 14 15
>>> print DiggPaginator(range(1,151), 10, body=6, padding=2, page=8)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
>>> print DiggPaginator(range(1,151), 10, body=6, padding=1, page=8)
1 2 3 4 5 6 7 8 9 ... 14 15
# no leading or trailing ranges might be required if there are only
# a very small number of pages
>>> print DiggPaginator(range(1,80), 10, body=10, page=1)
1 2 3 4 5 6 7 8
>>> print DiggPaginator(range(1,80), 10, body=10, page=8)
1 2 3 4 5 6 7 8
>>> print DiggPaginator(range(1,12), 10, body=5, page=1)
1 2
# padding: default value
>>> DiggPaginator(range(1,1000), 10, body=10).padding
4
# padding: automatic reduction
>>> DiggPaginator(range(1,1000), 10, body=5).padding
2
>>> DiggPaginator(range(1,1000), 10, body=6).padding
2
# padding: sanity check
>>> DiggPaginator(range(1,1000), 10, body=5, padding=3)
Traceback (most recent call last):
ValueError: padding too large for body (max 2)
"""
def __init__(self, *args, **kwargs):
self.body = kwargs.pop('body', 10)
self.tail = kwargs.pop('tail', 2)
self.margin = kwargs.pop('margin', 4) # todo: make default relative to body?
# validate padding value
max_padding = int(math.ceil(self.body/2.0)-1)
self.padding = kwargs.pop('padding', min(4, max_padding))
if self.padding > max_padding:
raise ValueError('padding too large for body (max %d)'%max_padding)
super(DiggPaginator, self).__init__(*args, **kwargs)
def update_attrs(self):
super(DiggPaginator, self).update_attrs()
# easier access
page, pages, body, tail, padding, margin = \
self.page, self.pages, self.body, self.tail, self.padding,\
self.margin
# put active page in middle of main range
main_range = map(int, [
math.floor(page-body/2.0)+1, # +1 = shift odd body to right
math.floor(page+body/2.0)])
# adjust bounds
if main_range[0] < 1:
main_range = map(abs(main_range[0]-1).__add__, main_range)
if main_range[1] > pages:
main_range = map((pages-main_range[1]).__add__, main_range)
# Determine leading and trailing ranges; if possible and appropriate,
# combine them with the main range, in which case the resulting main
# block might end up considerable larger than requested. While we
# can't guarantee the exact size in those cases, we can at least try
# to come as close as possible: we can reduce the other boundary to
# max padding, instead of using half the body size, which would
# otherwise be the case. If the padding is large enough, this will
# of course have no effect.
# Example:
# total pages=100, page=4, body=5, (default padding=2)
# 1 2 3 [4] 5 6 ... 99 100
# total pages=100, page=4, body=5, padding=1
# 1 2 3 [4] 5 ... 99 100
# If it were not for this adjustment, both cases would result in the
# first output, regardless of the padding value.
if main_range[0] <= tail+margin:
leading = []
main_range = [1, max(body, min(page+padding, main_range[1]))]
main_range[0] = 1
else:
leading = range(1, tail+1)
# basically same for trailing range...
if main_range[1] >= pages-(tail+margin)+1:
trailing = []
if not leading:
# ... but handle the special case of neither leading nor
# trailing ranges; otherwise, we would now modify the main
# range low bound, which we just set in the previous section,
# again.
main_range = [1, pages]
else:
main_range = [min(pages-body+1, max(page-padding, main_range[0])), pages]
else:
trailing = range(pages-tail+1, pages+1)
# finally, normalize values that are out of bound; this basically fixes
# all the things the above code screwed up in the simple case of few
# enough pages where one range would suffice.
main_range = [max(main_range[0], 1), min(main_range[1], pages)]
# set attributes
self.main_range = range(main_range[0], main_range[1]+1)
self.leading_range = leading
self.trailing_range = trailing
self.page_range = reduce(lambda x, y: x+((x and y) and [False])+y,
[self.leading_range, self.main_range, self.trailing_range])
def __str__(self):
return " ... ".join(filter(None, [
" ".join(map(str, self.leading_range)),
" ".join(map(str, self.main_range)),
" ".join(map(str, self.trailing_range))]))
if __name__ == "__main__":
import doctest
doctest.testmod()