forum/utils/pagination.py

   1 import math
   2 from django.utils.datastructures import SortedDict
   3 from django import template
   4 from django.core.paginator import Paginator, EmptyPage
   5 from django.utils.translation import ugettext as _
   6 from django.http import Http404
   7 from django.utils.safestring import mark_safe
   8 from django.utils.http import urlquote
   9 import logging
  10
  11 class SimpleSort(object):
  12     def __init__(self, label, order_by, description=''):
  13         self.label = label
  14         self.description = description
  15         self.order_by = order_by
  16
  17     def apply(self, objects):
  18         return objects.order_by(self.order_by)
  19
  20 class DummySort(object):
  21     def __init__(self, label, description=''):
  22         self.label = label
  23         self.description = description
  24
  25     def apply(self, objects):
  26         return objects
  27
  28
  29 class PaginatorContext(object):
  30     visible_page_range = 5
  31     outside_page_range = 1
  32
  33     base_path = None
  34
  35     def __init__(self, id, sort_methods=None, default_sort=None, force_sort = None, sticky_sort=False,
  36                  pagesizes=None, default_pagesize=None):
  37         self.id = id
  38         if sort_methods:
  39             self.has_sort = True
  40             self.sort_methods = SortedDict(data=sort_methods)
  41
  42             if not default_sort:
  43                 default_sort = sort_methods[0][0]
  44
  45             self.default_sort = default_sort
  46         else:
  47             self.has_sort = False
  48
  49
  50         if pagesizes:
  51             self.has_pagesize = True
  52             self.pagesizes = pagesizes
  53
  54             if not default_pagesize:
  55                 self.default_pagesize = pagesizes[int(math.ceil(float(len(pagesizes)) / 2)) - 1]
  56             else:
  57                 self.default_pagesize = default_pagesize
  58         else:
  59             self.has_pagesize = False
  60
  61         self.force_sort = force_sort
  62         self.sticky_sort = sticky_sort
  63
  64     def session_preferences(self, request):
  65         return request.session.get('paginator_%s' % self.id, {})
  66
  67     def pagesize(self, request, session_prefs=None):
  68         if not session_prefs:
  69             session_prefs = self.session_preferences(request)
  70
  71
  72         if self.has_pagesize:
  73             if request.GET.get(labels.PAGESIZE, None):
  74                 try:
  75                     pagesize = int(request.GET[labels.PAGESIZE])
  76                 except ValueError:
  77                     logging.error('Found invalid page size "%s", loading %s, refered by %s' % (
  78                         request.GET.get(labels.PAGESIZE, ''), request.path, request.META.get('HTTP_REFERER', 'UNKNOWN')
  79                     ))
  80                     raise Http404()
  81
  82                 session_prefs[labels.PAGESIZE] = pagesize
  83             else:
  84                 pagesize = session_prefs.get(labels.PAGESIZE, self.default_pagesize)
  85
  86             if not pagesize in self.pagesizes:
  87                 pagesize = self.default_pagesize
  88         else:
  89             pagesize = 30
  90
  91         return pagesize
  92
  93     def page(self, request):
  94         try:
  95             return int(request.GET.get(labels.PAGE, 1))
  96         except ValueError:
  97             logging.error('Found invalid page number "%s", loading %s, refered by %s' % (
  98                 request.GET.get(labels.PAGE, ''), request.path, request.META.get('HTTP_REFERER', 'UNKNOWN')
  99             ))
 100             raise Http404()
 101
 102     def sort(self, request, session_prefs=None):
 103         if not session_prefs:
 104             session_prefs = self.session_preferences(request)
 105
 106         sort = None
 107         if self.has_sort:
 108             if request.GET.get(labels.SORT, None):
 109                 sort = request.GET[labels.SORT]
 110                 if self.sticky_sort or session_prefs.get('sticky_sort', False):
 111                     session_prefs[labels.SORT] = sort
 112             else:
 113                 sort = self.force_sort or session_prefs.get(labels.SORT, self.default_sort)
 114
 115             if not sort in self.sort_methods:
 116                 sort = self.default_sort
 117
 118         return sort
 119
 120     def sorted(self, objects, request, session_prefs=None):
 121         sort = self.sort(request, session_prefs)
 122
 123         if sort:
 124             objects = self.sort_methods[sort].apply(objects)
 125
 126         return sort, objects
 127
 128
 129 class labels(object):
 130     PAGESIZE = _('pagesize')
 131     PAGE = _('page')
 132     SORT = _('sort')
 133
 134 page_numbers_template = template.loader.get_template('paginator/page_numbers.html')
 135 page_sizes_template = template.loader.get_template('paginator/page_sizes.html')
 136 sort_tabs_template = template.loader.get_template('paginator/sort_tabs.html')
 137
 138 def paginated(request, list_name, context, tpl_context):
 139     session_prefs = context.session_preferences(request)
 140
 141     objects = tpl_context[list_name]
 142
 143     pagesize = context.pagesize(request, session_prefs)
 144     page = context.page(request)
 145     sort, objects = context.sorted(objects, request, session_prefs)
 146
 147     paginator = Paginator(objects, pagesize)
 148
 149     try:
 150         page_obj = paginator.page(page)
 151     except EmptyPage:
 152         logging.error('Found invalid page number "%s", loading %s, refered by %s' % (
 153             request.GET.get(labels.PAGE, ''), request.path, request.META.get('HTTP_REFERER', 'UNKNOWN')
 154         ))
 155         raise Http404()
 156
 157     if context.base_path:
 158         base_path = context.base_path
 159     else:
 160         base_path = request.path
 161         get_params = ["%s=%s" % (k, v) for k, v in request.GET.items() if not k in (labels.PAGE, labels.PAGESIZE, labels.SORT)]
 162
 163         if get_params:
 164             base_path += "?" + "&".join(get_params)
 165
 166     url_joiner = "?" in base_path and "&" or "?"
 167
 168
 169     def get_page():
 170         object_list = page_obj.object_list
 171
 172         if hasattr(object_list, 'lazy'):
 173             return object_list.lazy()
 174         return page_obj.object_list
 175     objects.page = get_page
 176
 177     total_pages = paginator.num_pages
 178
 179     if total_pages > 1:
 180         def page_nums():
 181             total_pages = paginator.num_pages
 182
 183             has_previous = page > 1
 184             has_next = page < total_pages
 185
 186             range_start = page - context.visible_page_range / 2
 187             range_end = page + context.visible_page_range / 2
 188
 189             if range_start < 1:
 190                 range_end = context.visible_page_range
 191                 range_start = 1
 192
 193             if range_end > total_pages:
 194                 range_start = total_pages - context.visible_page_range + 1
 195                 range_end = total_pages
 196                 if range_start < 1:
 197                     range_start = 1
 198
 199             page_numbers = []
 200
 201             if sort:
 202                 url_builder = lambda n: mark_safe("%s%s%s=%s&%s=%s" % (base_path, url_joiner, labels.SORT, sort, labels.PAGE, n))
 203             else:
 204                 url_builder = lambda n: mark_safe("%s%s%s=%s" % (base_path, url_joiner, labels.PAGE, n))
 205
 206             if range_start > (context.outside_page_range + 1):
 207                 page_numbers.append([(n, url_builder(n)) for n in range(1, context.outside_page_range + 1)])
 208                 page_numbers.append(None)
 209             elif range_start > 1:
 210                 page_numbers.append([(n, url_builder(n)) for n in range(1, range_start)])
 211
 212             page_numbers.append([(n, url_builder(n)) for n in range(range_start, range_end + 1)])
 213
 214             if range_end < (total_pages - context.outside_page_range):
 215                 page_numbers.append(None)
 216                 page_numbers.append([(n, url_builder(n)) for n in range(total_pages - context.outside_page_range + 1, total_pages + 1)])
 217             elif range_end < total_pages:
 218                 page_numbers.append([(n, url_builder(n)) for n in range(range_end + 1, total_pages + 1)])
 219
 220             return page_numbers_template.render(template.Context({
 221                 'has_previous': has_previous,
 222                 'previous_url': has_previous and url_builder(page - 1) or None,
 223                 'has_next': has_next,
 224                 'next_url': has_next and url_builder(page + 1) or None,
 225                 'current': page,
 226                 'page_numbers': page_numbers
 227             }))
 228         objects.page_numbers = page_nums
 229     else:
 230         objects.page_numbers = ''
 231
 232     if pagesize:
 233         def page_sizes():
 234             if sort:
 235                 url_builder = lambda s: mark_safe("%s%s%s=%s&%s=%s" % (base_path, url_joiner, labels.SORT, sort, labels.PAGESIZE, s))
 236             else:
 237                 url_builder = lambda s: mark_safe("%s%s%s=%s" % (base_path, url_joiner, labels.PAGESIZE, s))
 238
 239             sizes = [(s, url_builder(s)) for s in context.pagesizes]
 240
 241             return page_sizes_template.render(template.Context({
 242                 'current': pagesize,
 243                 'sizes': sizes
 244             }))
 245
 246         objects.page_sizes = page_sizes
 247     else:
 248         objects.page_sizes = ''
 249
 250     if sort:
 251         def sort_tabs():
 252             url_builder = lambda s: mark_safe("%s%s%s=%s" % (base_path, url_joiner, labels.SORT, s))
 253             sorts = [(n, s.label, url_builder(n), s.description) for n, s in context.sort_methods.items()]
 254
 255             return sort_tabs_template.render(template.Context({
 256                 'current': sort,
 257                 'sorts': sorts,
 258                 'sticky': session_prefs.get('sticky_sort', False)
 259             }))
 260         objects.sort_tabs = sort_tabs()
 261     else:
 262         objects.sort_tabs = ''
 263
 264     request.session['paginator_%s' % context.id] = session_prefs
 265     tpl_context[list_name] = objects
 266     return tpl_context