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()