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, prefix=''):
  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         self.prefix = prefix
  64
  65     def session_preferences(self, request):
  66         return request.session.get('paginator_%s%s' % (self.prefix, self.id), {})
  67
  68     def pagesize(self, request, session_prefs=None):
  69         if not session_prefs:
  70             session_prefs = self.session_preferences(request)
  71
  72
  73         if self.has_pagesize:
  74             if request.GET.get(self.PAGESIZE, None):
  75                 try:
  76                     pagesize = int(request.GET[self.PAGESIZE])
  77                 except ValueError:
  78                     logging.error('Found invalid page size "%s", loading %s, refered by %s' % (
  79                         request.GET.get(self.PAGESIZE, ''), request.path, request.META.get('HTTP_REFERER', 'UNKNOWN')
  80                     ))
  81                     raise Http404()
  82
  83                 session_prefs[self.PAGESIZE] = pagesize
  84             else:
  85                 pagesize = session_prefs.get(self.PAGESIZE, self.default_pagesize)
  86
  87             if not pagesize in self.pagesizes:
  88                 pagesize = self.default_pagesize
  89         else:
  90             pagesize = 30
  91
  92         return pagesize
  93
  94     def page(self, request):
  95         try:
  96             return int(request.GET.get(self.PAGE, 1))
  97         except ValueError:
  98             logging.error('Found invalid page number "%s", loading %s, refered by %s' % (
  99                 request.GET.get(self.PAGE, ''), request.path, request.META.get('HTTP_REFERER', 'UNKNOWN')
 100             ))
 101             raise Http404()
 102
 103     def sort(self, request, session_prefs=None):
 104         if not session_prefs:
 105             session_prefs = self.session_preferences(request)
 106
 107         sort = None
 108         if self.has_sort:
 109             if request.GET.get(self.SORT, None):
 110                 sort = request.GET[self.SORT]
 111                 if self.sticky_sort or session_prefs.get('sticky_sort', False):
 112                     session_prefs[self.SORT] = sort
 113             else:
 114                 sort = self.force_sort or session_prefs.get(self.SORT, self.default_sort)
 115
 116             if not sort in self.sort_methods:
 117                 sort = self.default_sort
 118
 119         return sort
 120
 121     def sorted(self, objects, request, session_prefs=None):
 122         sort = self.sort(request, session_prefs)
 123
 124         if sort:
 125             objects = self.sort_methods[sort].apply(objects)
 126
 127         return sort, objects
 128
 129     @property
 130     def PAGESIZE(self):
 131         return self.prefix and "%s_%s" % (self.prefix, _('pagesize')) or _('pagesize')
 132
 133     @property
 134     def PAGE(self):
 135         return self.prefix and "%s_%s" % (self.prefix, _('page')) or _('page')
 136
 137     @property
 138     def SORT(self):
 139         return self.prefix and "%s_%s" % (self.prefix, _('sort')) or _('sort')
 140
 141 page_numbers_template = template.loader.get_template('paginator/page_numbers.html')
 142 page_sizes_template = template.loader.get_template('paginator/page_sizes.html')
 143 sort_tabs_template = template.loader.get_template('paginator/sort_tabs.html')
 144
 145 def paginated(request, paginators, tpl_context):
 146     if len(paginators) == 2 and isinstance(paginators[0], basestring):
 147         paginators = (paginators,)
 148
 149     for list_name, context in paginators:
 150         tpl_context[list_name] = _paginated(request, tpl_context[list_name], context)
 151
 152     return tpl_context
 153
 154 def _paginated(request, objects, context):
 155     session_prefs = context.session_preferences(request)
 156
 157     pagesize = context.pagesize(request, session_prefs)
 158     page = context.page(request)
 159     sort, objects = context.sorted(objects, request, session_prefs)
 160
 161     paginator = Paginator(objects, pagesize)
 162
 163     try:
 164         page_obj = paginator.page(page)
 165     except EmptyPage:
 166         logging.error('Found invalid page number "%s", loading %s, refered by %s' % (
 167             request.GET.get(context.PAGE, ''), request.path, request.META.get('HTTP_REFERER', 'UNKNOWN')
 168         ))
 169         raise Http404()
 170
 171     if context.base_path:
 172         base_path = context.base_path
 173     else:
 174         base_path = request.path
 175         get_params = ["%s=%s" % (k, v) for k, v in request.GET.items() if not k in (context.PAGE, context.PAGESIZE, context.SORT)]
 176
 177         if get_params:
 178             base_path += "?" + "&".join(get_params)
 179
 180     url_joiner = "?" in base_path and "&" or "?"
 181
 182
 183     def get_page():
 184         object_list = page_obj.object_list
 185
 186         if hasattr(object_list, 'lazy'):
 187             return object_list.lazy()
 188         return object_list
 189     paginator.page = get_page()
 190
 191     total_pages = paginator.num_pages
 192
 193     if total_pages > 1:
 194         def page_nums():
 195             total_pages = paginator.num_pages
 196
 197             has_previous = page > 1
 198             has_next = page < total_pages
 199
 200             range_start = page - context.visible_page_range / 2
 201             range_end = page + context.visible_page_range / 2
 202
 203             if range_start < 1:
 204                 range_end = context.visible_page_range
 205                 range_start = 1
 206
 207             if range_end > total_pages:
 208                 range_start = total_pages - context.visible_page_range + 1
 209                 range_end = total_pages
 210                 if range_start < 1:
 211                     range_start = 1
 212
 213             page_numbers = []
 214
 215             if sort:
 216                 url_builder = lambda n: mark_safe("%s%s%s=%s&%s=%s" % (base_path, url_joiner, context.SORT, sort, context.PAGE, n))
 217             else:
 218                 url_builder = lambda n: mark_safe("%s%s%s=%s" % (base_path, url_joiner, context.PAGE, n))
 219
 220             if range_start > (context.outside_page_range + 1):
 221                 page_numbers.append([(n, url_builder(n)) for n in range(1, context.outside_page_range + 1)])
 222                 page_numbers.append(None)
 223             elif range_start > 1:
 224                 page_numbers.append([(n, url_builder(n)) for n in range(1, range_start)])
 225
 226             page_numbers.append([(n, url_builder(n)) for n in range(range_start, range_end + 1)])
 227
 228             if range_end < (total_pages - context.outside_page_range):
 229                 page_numbers.append(None)
 230                 page_numbers.append([(n, url_builder(n)) for n in range(total_pages - context.outside_page_range + 1, total_pages + 1)])
 231             elif range_end < total_pages:
 232                 page_numbers.append([(n, url_builder(n)) for n in range(range_end + 1, total_pages + 1)])
 233
 234             return page_numbers_template.render(template.Context({
 235                 'has_previous': has_previous,
 236                 'previous_url': has_previous and url_builder(page - 1) or None,
 237                 'has_next': has_next,
 238                 'next_url': has_next and url_builder(page + 1) or None,
 239                 'current': page,
 240                 'page_numbers': page_numbers
 241             }))
 242         paginator.page_numbers = page_nums
 243     else:
 244         paginator.page_numbers = ''
 245
 246     if pagesize:
 247         def page_sizes():
 248             if sort:
 249                 url_builder = lambda s: mark_safe("%s%s%s=%s&%s=%s" % (base_path, url_joiner, context.SORT, sort, context.PAGESIZE, s))
 250             else:
 251                 url_builder = lambda s: mark_safe("%s%s%s=%s" % (base_path, url_joiner, context.PAGESIZE, s))
 252
 253             sizes = [(s, url_builder(s)) for s in context.pagesizes]
 254
 255             return page_sizes_template.render(template.Context({
 256                 'current': pagesize,
 257                 'sizes': sizes
 258             }))
 259
 260         paginator.page_sizes = page_sizes
 261     else:
 262         paginator.page_sizes = ''
 263
 264     if sort:
 265         def sort_tabs():
 266             url_builder = lambda s: mark_safe("%s%s%s=%s" % (base_path, url_joiner, context.SORT, s))
 267             sorts = [(n, s.label, url_builder(n), s.description) for n, s in context.sort_methods.items()]
 268
 269             return sort_tabs_template.render(template.Context({
 270                 'current': sort,
 271                 'sorts': sorts,
 272                 'sticky': session_prefs.get('sticky_sort', False)
 273             }))
 274         paginator.sort_tabs = sort_tabs()
 275     else:
 276         paginator.sort_tabs = ''
 277
 278     request.session['paginator_%s' % context.id] = session_prefs
 279     objects.paginator = paginator
 280     return objects