models/base.py

   1 from django.db import models
   2 from django.contrib.contenttypes.models import ContentType
   3 from django.contrib.contenttypes import generic
   4 from django.utils import simplejson as json
   5 from django.core.exceptions import ObjectDoesNotExist
   6 from philo.utils import ContentTypeRegistryLimiter
   7 from philo.signals import entity_class_prepared
   8 from UserDict import DictMixin
   9
  10
  11 class Tag(models.Model):
  12         name = models.CharField(max_length=250)
  13         slug = models.SlugField(unique=True)
  14
  15         def __unicode__(self):
  16                 return self.name
  17
  18         class Meta:
  19                 app_label = 'philo'
  20
  21
  22 class Titled(models.Model):
  23         title = models.CharField(max_length=255)
  24         slug = models.SlugField(max_length=255)
  25
  26         def __unicode__(self):
  27                 return self.title
  28
  29         class Meta:
  30                 abstract = True
  31
  32
  33 class Attribute(models.Model):
  34         entity_content_type = models.ForeignKey(ContentType, verbose_name='Entity type')
  35         entity_object_id = models.PositiveIntegerField(verbose_name='Entity ID')
  36         entity = generic.GenericForeignKey('entity_content_type', 'entity_object_id')
  37         key = models.CharField(max_length=255)
  38         json_value = models.TextField(verbose_name='Value (JSON)', help_text='This value must be valid JSON.')
  39
  40         def get_value(self):
  41                 return json.loads(self.json_value)
  42
  43         def set_value(self, value):
  44                 self.json_value = json.dumps(value)
  45
  46         def delete_value(self):
  47                 self.json_value = json.dumps(None)
  48
  49         value = property(get_value, set_value, delete_value)
  50
  51         def __unicode__(self):
  52                 return u'"%s": %s' % (self.key, self.value)
  53
  54         class Meta:
  55                 app_label = 'philo'
  56
  57
  58 value_content_type_limiter = ContentTypeRegistryLimiter()
  59
  60
  61 def register_value_model(model):
  62         value_content_type_limiter.register_class(model)
  63
  64
  65 def unregister_value_model(model):
  66         value_content_type_limiter.unregister_class(model)
  67
  68
  69
  70 class Relationship(models.Model):
  71         entity_content_type = models.ForeignKey(ContentType, related_name='relationship_entity_set', verbose_name='Entity type')
  72         entity_object_id = models.PositiveIntegerField(verbose_name='Entity ID')
  73         entity = generic.GenericForeignKey('entity_content_type', 'entity_object_id')
  74         key = models.CharField(max_length=255)
  75         value_content_type = models.ForeignKey(ContentType, related_name='relationship_value_set', limit_choices_to=value_content_type_limiter, verbose_name='Value type', null=True, blank=True)
  76         value_object_id = models.PositiveIntegerField(verbose_name='Value ID', null=True, blank=True)
  77         value = generic.GenericForeignKey('value_content_type', 'value_object_id')
  78
  79         def __unicode__(self):
  80                 return u'"%s": %s' % (self.key, self.value)
  81
  82         class Meta:
  83                 app_label = 'philo'
  84
  85
  86 class QuerySetMapper(object, DictMixin):
  87         def __init__(self, queryset, passthrough=None):
  88                 self.queryset = queryset
  89                 self.passthrough = passthrough
  90
  91         def __getitem__(self, key):
  92                 try:
  93                         return self.queryset.get(key__exact=key).value
  94                 except ObjectDoesNotExist:
  95                         if self.passthrough is not None:
  96                                 return self.passthrough.__getitem__(key)
  97                         raise KeyError
  98
  99         def keys(self):
 100                 keys = set(self.queryset.values_list('key', flat=True).distinct())
 101                 if self.passthrough is not None:
 102                         keys |= set(self.passthrough.keys())
 103                 return list(keys)
 104
 105
 106 class EntityOptions(object):
 107         def __init__(self, options):
 108                 if options is not None:
 109                         for key, value in options.__dict__.items():
 110                                 setattr(self, key, value)
 111                 if not hasattr(self, 'proxy_fields'):
 112                         self.proxy_fields = []
 113
 114         def add_proxy_field(self, proxy_field):
 115                 self.proxy_fields.append(proxy_field)
 116
 117
 118 class EntityBase(models.base.ModelBase):
 119         def __new__(cls, name, bases, attrs):
 120                 new = super(EntityBase, cls).__new__(cls, name, bases, attrs)
 121                 entity_options = attrs.pop('EntityMeta', None)
 122                 setattr(new, '_entity_meta', EntityOptions(entity_options))
 123                 entity_class_prepared.send(sender=new)
 124                 return new
 125
 126
 127 class Entity(models.Model):
 128         __metaclass__ = EntityBase
 129
 130         attribute_set = generic.GenericRelation(Attribute, content_type_field='entity_content_type', object_id_field='entity_object_id')
 131         relationship_set = generic.GenericRelation(Relationship, content_type_field='entity_content_type', object_id_field='entity_object_id')
 132
 133         @property
 134         def attributes(self):
 135                 return QuerySetMapper(self.attribute_set)
 136
 137         @property
 138         def relationships(self):
 139                 return QuerySetMapper(self.relationship_set)
 140
 141         @property
 142         def _added_attribute_registry(self):
 143                 if not hasattr(self, '_real_added_attribute_registry'):
 144                         self._real_added_attribute_registry = {}
 145                 return self._real_added_attribute_registry
 146
 147         @property
 148         def _removed_attribute_registry(self):
 149                 if not hasattr(self, '_real_removed_attribute_registry'):
 150                         self._real_removed_attribute_registry = []
 151                 return self._real_removed_attribute_registry
 152
 153         @property
 154         def _added_relationship_registry(self):
 155                 if not hasattr(self, '_real_added_relationship_registry'):
 156                         self._real_added_relationship_registry = {}
 157                 return self._real_added_relationship_registry
 158
 159         @property
 160         def _removed_relationship_registry(self):
 161                 if not hasattr(self, '_real_removed_relationship_registry'):
 162                         self._real_removed_relationship_registry = []
 163                 return self._real_removed_relationship_registry
 164
 165         def save(self, *args, **kwargs):
 166                 super(Entity, self).save(*args, **kwargs)
 167
 168                 for key in self._removed_attribute_registry:
 169                         self.attribute_set.filter(key__exact=key).delete()
 170                 del self._removed_attribute_registry[:]
 171
 172                 for key, value in self._added_attribute_registry.items():
 173                         try:
 174                                 attribute = self.attribute_set.get(key__exact=key)
 175                         except Attribute.DoesNotExist:
 176                                 attribute = Attribute()
 177                                 attribute.entity = self
 178                                 attribute.key = key
 179                         attribute.value = value
 180                         attribute.save()
 181                 self._added_attribute_registry.clear()
 182
 183                 for key in self._removed_relationship_registry:
 184                         self.relationship_set.filter(key__exact=key).delete()
 185                 del self._removed_relationship_registry[:]
 186
 187                 for key, value in self._added_relationship_registry.items():
 188                         try:
 189                                 relationship = self.relationship_set.get(key__exact=key)
 190                         except Relationship.DoesNotExist:
 191                                 relationship = Relationship()
 192                                 relationship.entity = self
 193                                 relationship.key = key
 194                         relationship.value = value
 195                         relationship.save()
 196                 self._added_relationship_registry.clear()
 197
 198         class Meta:
 199                 abstract = True
 200
 201
 202 class TreeManager(models.Manager):
 203         use_for_related_fields = True
 204
 205         def roots(self):
 206                 return self.filter(parent__isnull=True)
 207
 208         def get_with_path(self, path, root=None, absolute_result=True, pathsep='/'):
 209                 """
 210                 Returns the object with the path, or None if there is no object with that path,
 211                 unless absolute_result is set to False, in which case it returns a tuple containing
 212                 the deepest object found along the path, and the remainder of the path after that
 213                 object as a string (or None in the case that there is no remaining path).
 214                 """
 215                 slugs = path.split(pathsep)
 216                 obj = root
 217                 remaining_slugs = list(slugs)
 218                 remainder = None
 219                 for slug in slugs:
 220                         remaining_slugs.remove(slug)
 221                         if slug: # ignore blank slugs, handles for multiple consecutive pathseps
 222                                 try:
 223                                         obj = self.get(slug__exact=slug, parent__exact=obj)
 224                                 except self.model.DoesNotExist:
 225                                         if absolute_result:
 226                                                 obj = None
 227                                         remaining_slugs.insert(0, slug)
 228                                         remainder = pathsep.join(remaining_slugs)
 229                                         break
 230                 if obj:
 231                         if absolute_result:
 232                                 return obj
 233                         else:
 234                                 return (obj, remainder)
 235                 raise self.model.DoesNotExist('%s matching query does not exist.' % self.model._meta.object_name)
 236
 237
 238 class TreeModel(models.Model):
 239         objects = TreeManager()
 240         parent = models.ForeignKey('self', related_name='children', null=True, blank=True)
 241         slug = models.SlugField()
 242
 243         def has_ancestor(self, ancestor):
 244                 parent = self
 245                 while parent:
 246                         if parent == ancestor:
 247                                 return True
 248                         parent = parent.parent
 249                 return False
 250
 251         def get_path(self, root=None, pathsep='/', field='slug'):
 252                 if root is not None and self.has_ancestor(root):
 253                         path = ''
 254                         parent = self
 255                         while parent and parent != root:
 256                                 path = getattr(parent, field, '?') + pathsep + path
 257                                 parent = parent.parent
 258                         return path
 259                 else:
 260                         path = getattr(self, field, '?')
 261                         parent = self.parent
 262                         while parent and parent != root:
 263                                 path = getattr(parent, field, '?') + pathsep + path
 264                                 parent = parent.parent
 265                         return path
 266         path = property(get_path)
 267
 268         def __unicode__(self):
 269                 return self.path
 270
 271         class Meta:
 272                 unique_together = (('parent', 'slug'),)
 273                 abstract = True
 274
 275
 276 class TreeEntity(TreeModel, Entity):
 277         @property
 278         def attributes(self):
 279                 if self.parent:
 280                         return QuerySetMapper(self.attribute_set, passthrough=self.parent.attributes)
 281                 return super(TreeEntity, self).attributes
 282
 283         @property
 284         def relationships(self):
 285                 if self.parent:
 286                         return QuerySetMapper(self.relationship_set, passthrough=self.parent.relationships)
 287                 return super(TreeEntity, self).relationships
 288
 289         class Meta:
 290                 abstract = True