philo/contrib/shipherd/models.py

   1 #encoding: utf-8
   2 from UserDict import DictMixin
   3 from hashlib import sha1
   4
   5 from django.core.cache import cache
   6 from django.core.exceptions import ValidationError
   7 from django.core.urlresolvers import NoReverseMatch
   8 from django.core.validators import RegexValidator, MinValueValidator
   9 from django.db import models
  10 from django.forms.models import model_to_dict
  11
  12 from philo.models.base import TreeEntity, TreeEntityManager, Entity
  13 from philo.models.nodes import Node, TargetURLModel
  14
  15
  16 DEFAULT_NAVIGATION_DEPTH = 3
  17
  18
  19 class NavigationMapper(object, DictMixin):
  20         """
  21         The :class:`NavigationMapper` is a dictionary-like object which allows easy fetching of the root items of a navigation for a node according to a key. A :class:`NavigationMapper` instance will be available on each node instance as :attr:`Node.navigation` if :mod:`~philo.contrib.shipherd` is in the :setting:`INSTALLED_APPS`
  22
  23         """
  24         def __init__(self, node):
  25                 self.node = node
  26                 self._cache = {}
  27
  28         def __getitem__(self, key):
  29                 return Navigation.objects.get_for_node(self.node, key)
  30                 #if key not in self._cache:
  31                 #       try:
  32                 #               self._cache[key] = Navigation.objects.get_for_node(self.node, key)
  33                 #       except Navigation.DoesNotExist:
  34                 #               self._cache[key] = None
  35                 #return self._cache[key]
  36
  37
  38 def navigation(self):
  39         if not hasattr(self, '_navigation'):
  40                 self._navigation = NavigationMapper(self)
  41         return self._navigation
  42
  43
  44 Node.navigation = property(navigation)
  45
  46
  47 class NavigationManager(models.Manager):
  48         use_for_related = True
  49
  50         def get_for_node(self, node, key):
  51                 cache_key = self._get_cache_key(node, key)
  52                 cached = cache.get(cache_key)
  53
  54                 if cached is None:
  55                         opts = Node._mptt_meta
  56                         left = getattr(node, opts.left_attr)
  57                         right = getattr(node, opts.right_attr)
  58                         tree_id = getattr(node, opts.tree_id_attr)
  59                         kwargs = {
  60                                 "node__%s__lte" % opts.left_attr: left,
  61                                 "node__%s__gte" % opts.right_attr: right,
  62                                 "node__%s" % opts.tree_id_attr: tree_id
  63                         }
  64                         navs = self.filter(key=key, **kwargs).select_related('node').order_by('-node__%s' % opts.level_attr)
  65                         nav = navs[0]
  66                         roots = nav.roots.all().select_related('target_node')
  67                         item_opts = NavigationItem._mptt_meta
  68                         by_pk = {}
  69                         tree_ids = []
  70
  71                         for root in roots:
  72                                 by_pk[root.pk] = root
  73                                 tree_ids.append(getattr(root, item_opts.tree_id_attr))
  74                                 root._cached_children = []
  75
  76                         kwargs = {
  77                                 '%s__in' % item_opts.tree_id_attr: tree_ids,
  78                                 '%s__lt' % item_opts.level_attr: nav.depth,
  79                                 '%s__gt' % item_opts.level_attr: 0
  80                         }
  81                         items = NavigationItem.objects.filter(**kwargs).select_related('target_node').order_by('level', 'order')
  82                         for item in items:
  83                                 by_pk[item.pk] = item
  84                                 item._cached_children = []
  85                                 parent_pk = getattr(item, '%s_id' % item_opts.parent_attr)
  86                                 item.parent = by_pk[parent_pk]
  87                                 item.parent._cached_children.append(item)
  88
  89                         cached = roots
  90                         cache.set(cache_key, cached)
  91
  92                 return cached
  93
  94         def _get_cache_key(self, node, key):
  95                 opts = Node._mptt_meta
  96                 left = getattr(node, opts.left_attr)
  97                 right = getattr(node, opts.right_attr)
  98                 tree_id = getattr(node, opts.tree_id_attr)
  99                 parent_id = getattr(node, "%s_id" % opts.parent_attr)
 100
 101                 return sha1(unicode(left) + unicode(right) + unicode(tree_id) + unicode(parent_id) + unicode(node.pk) + unicode(key)).hexdigest()
 102
 103
 104 class Navigation(Entity):
 105         """
 106         :class:`Navigation` represents a group of :class:`NavigationItem`\ s that have an intrinsic relationship in terms of navigating a website. For example, a ``main`` navigation versus a ``side`` navigation, or a ``authenticated`` navigation versus an ``anonymous`` navigation.
 107
 108         A :class:`Navigation`'s :class:`NavigationItem`\ s will be accessible from its related :class:`.Node` and that :class:`.Node`'s descendants through a :class:`NavigationMapper` instance at :attr:`Node.navigation`. Example::
 109
 110                 >>> node.navigation_set.all()
 111                 []
 112                 >>> parent = node.parent
 113                 >>> items = parent.navigation_set.get(key='main').roots.all()
 114                 >>> parent.navigation["main"] == node.navigation["main"] == list(items)
 115                 True
 116
 117         """
 118         #: A :class:`NavigationManager` instance.
 119         objects = NavigationManager()
 120
 121         #: The :class:`.Node` which the :class:`Navigation` is attached to. The :class:`Navigation` will also be available to all the :class:`.Node`'s descendants and will override any :class:`Navigation` with the same key on any of the :class:`.Node`'s ancestors.
 122         node = models.ForeignKey(Node, related_name='navigation_set', help_text="Be available as navigation for this node.")
 123         #: Each :class:`Navigation` has a ``key`` which consists of one or more word characters so that it can easily be accessed in a template as ``{{ node.navigation.this_key }}``.
 124         key = models.CharField(max_length=255, validators=[RegexValidator("\w+")], help_text="Must contain one or more alphanumeric characters or underscores.", db_index=True)
 125         #: There is no limit to the depth of a tree of :class:`NavigationItem`\ s, but ``depth`` will limit how much of the tree will be displayed.
 126         depth = models.PositiveSmallIntegerField(default=DEFAULT_NAVIGATION_DEPTH, validators=[MinValueValidator(1)], help_text="Defines the maximum display depth of this navigation.")
 127
 128         def __unicode__(self):
 129                 return "%s[%s]" % (self.node, self.key)
 130
 131         class Meta:
 132                 unique_together = ('node', 'key')
 133
 134
 135 class NavigationItem(TreeEntity, TargetURLModel):
 136         #: A :class:`ForeignKey` to a :class:`Navigation` instance. If this is not null, then the :class:`NavigationItem` will be a root node of the :class:`Navigation` instance.
 137         navigation = models.ForeignKey(Navigation, blank=True, null=True, related_name='roots', help_text="Be a root in this navigation tree.")
 138         #: The text which will be displayed in the navigation. This is a :class:`CharField` instance with max length 50.
 139         text = models.CharField(max_length=50)
 140
 141         #: The order in which the :class:`NavigationItem` will be displayed.
 142         order = models.PositiveSmallIntegerField(default=0)
 143
 144         def get_path(self, root=None, pathsep=u' › ', field='text'):
 145                 return super(NavigationItem, self).get_path(root, pathsep, field)
 146         path = property(get_path)
 147
 148         def clean(self):
 149                 super(NavigationItem, self).clean()
 150                 if bool(self.parent) == bool(self.navigation):
 151                         raise ValidationError("Exactly one of `parent` and `navigation` must be defined.")
 152
 153         def is_active(self, request):
 154                 """Returns ``True`` if the :class:`NavigationItem` is considered active for a given request and ``False`` otherwise."""
 155                 if self.target_url == request.path:
 156                         # Handle the `default` case where the target_url and requested path
 157                         # are identical.
 158                         return True
 159
 160                 if self.target_node is None and self.url_or_subpath == "http%s://%s%s" % (request.is_secure() and 's' or '', request.get_host(), request.path):
 161                         # If there's no target_node, double-check whether it's a full-url
 162                         # match.
 163                         return True
 164
 165                 if self.target_node and not self.url_or_subpath:
 166                         # If there is a target node and it's targeted simply, but the target URL is not
 167                         # the same as the request path, check whether the target node is an ancestor
 168                         # of the requested node. If so, this is active unless the target node
 169                         # is the same as the ``host node`` for this navigation structure.
 170                         try:
 171                                 host_node = self.get_root().navigation.node
 172                         except AttributeError:
 173                                 pass
 174                         else:
 175                                 if self.target_node != host_node and self.target_node.is_ancestor_of(request.node):
 176                                         return True
 177
 178                 return False
 179
 180         def has_active_descendants(self, request):
 181                 """Returns ``True`` if the :class:`NavigationItem` has active descendants and ``False`` otherwise."""
 182                 for child in self.get_children():
 183                         if child.is_active(request) or child.has_active_descendants(request):
 184                                 return True
 185                 return False