models/base.py

   1 from django import forms
   2 from django.db import models
   3 from django.contrib.contenttypes.models import ContentType
   4 from django.contrib.contenttypes import generic
   5 from django.utils import simplejson as json
   6 from django.core.exceptions import ObjectDoesNotExist
   7 from philo.exceptions import AncestorDoesNotExist
   8 from philo.models.fields import JSONField
   9 from philo.utils import ContentTypeRegistryLimiter, ContentTypeSubclassLimiter
  10 from philo.signals import entity_class_prepared
  11 from philo.validators import json_validator
  12 from UserDict import DictMixin
  13 from mptt.models import MPTTModel, MPTTModelBase, MPTTOptions
  14
  15
  16 class Tag(models.Model):
  17         name = models.CharField(max_length=255)
  18         slug = models.SlugField(max_length=255, unique=True)
  19
  20         def __unicode__(self):
  21                 return self.name
  22
  23         class Meta:
  24                 app_label = 'philo'
  25
  26
  27 class Titled(models.Model):
  28         title = models.CharField(max_length=255)
  29         slug = models.SlugField(max_length=255)
  30
  31         def __unicode__(self):
  32                 return self.title
  33
  34         class Meta:
  35                 abstract = True
  36
  37
  38 value_content_type_limiter = ContentTypeRegistryLimiter()
  39
  40
  41 def register_value_model(model):
  42         value_content_type_limiter.register_class(model)
  43
  44
  45 def unregister_value_model(model):
  46         value_content_type_limiter.unregister_class(model)
  47
  48
  49 class AttributeValue(models.Model):
  50         attribute_set = generic.GenericRelation('Attribute', content_type_field='value_content_type', object_id_field='value_object_id')
  51
  52         @property
  53         def attribute(self):
  54                 return self.attribute_set.all()[0]
  55
  56         def apply_data(self, data):
  57                 raise NotImplementedError
  58
  59         def value_formfield(self, **kwargs):
  60                 raise NotImplementedError
  61
  62         def __unicode__(self):
  63                 return unicode(self.value)
  64
  65         class Meta:
  66                 abstract = True
  67
  68
  69 attribute_value_limiter = ContentTypeSubclassLimiter(AttributeValue)
  70
  71
  72 class JSONValue(AttributeValue):
  73         value = JSONField() #verbose_name='Value (JSON)', help_text='This value must be valid JSON.')
  74
  75         def __unicode__(self):
  76                 return self.value_json
  77
  78         def value_formfield(self, **kwargs):
  79                 kwargs['initial'] = self.value_json
  80                 return self._meta.get_field('value').formfield(**kwargs)
  81
  82         def apply_data(self, cleaned_data):
  83                 self.value = cleaned_data.get('value', None)
  84
  85         class Meta:
  86                 app_label = 'philo'
  87
  88
  89 class ForeignKeyValue(AttributeValue):
  90         content_type = models.ForeignKey(ContentType, limit_choices_to=value_content_type_limiter, verbose_name='Value type', null=True, blank=True)
  91         object_id = models.PositiveIntegerField(verbose_name='Value ID', null=True, blank=True)
  92         value = generic.GenericForeignKey()
  93
  94         def value_formfield(self, form_class=forms.ModelChoiceField, **kwargs):
  95                 if self.content_type is None:
  96                         return None
  97                 kwargs.update({'initial': self.object_id, 'required': False})
  98                 return form_class(self.content_type.model_class()._default_manager.all(), **kwargs)
  99
 100         def apply_data(self, cleaned_data):
 101                 if 'value' in cleaned_data and cleaned_data['value'] is not None:
 102                         self.value = cleaned_data['value']
 103                 else:
 104                         self.content_type = cleaned_data.get('content_type', None)
 105                         # If there is no value set in the cleaned data, clear the stored value.
 106                         self.object_id = None
 107
 108         class Meta:
 109                 app_label = 'philo'
 110
 111
 112 class ManyToManyValue(AttributeValue):
 113         content_type = models.ForeignKey(ContentType, limit_choices_to=value_content_type_limiter, verbose_name='Value type', null=True, blank=True)
 114         values = models.ManyToManyField(ForeignKeyValue, blank=True, null=True)
 115
 116         def get_object_id_list(self):
 117                 if not self.values.count():
 118                         return []
 119                 else:
 120                         return self.values.values_list('object_id', flat=True)
 121
 122         def get_value(self):
 123                 if self.content_type is None:
 124                         return None
 125
 126                 return self.content_type.model_class()._default_manager.filter(id__in=self.get_object_id_list())
 127
 128         def set_value(self, value):
 129                 # Value is probably a queryset - but allow any iterable.
 130
 131                 # These lines shouldn't be necessary; however, if value is an EmptyQuerySet,
 132                 # the code (specifically the object_id__in query) won't work without them. Unclear why...
 133                 if not value:
 134                         value = []
 135
 136                 # Before we can fiddle with the many-to-many to foreignkeyvalues, we need
 137                 # a pk.
 138                 if self.pk is None:
 139                         self.save()
 140
 141                 if isinstance(value, models.query.QuerySet):
 142                         value = value.values_list('id', flat=True)
 143
 144                 self.values.filter(~models.Q(object_id__in=value)).delete()
 145                 current = self.get_object_id_list()
 146
 147                 for v in value:
 148                         if v in current:
 149                                 continue
 150                         self.values.create(content_type=self.content_type, object_id=v)
 151
 152         value = property(get_value, set_value)
 153
 154         def value_formfield(self, form_class=forms.ModelMultipleChoiceField, **kwargs):
 155                 if self.content_type is None:
 156                         return None
 157                 kwargs.update({'initial': self.get_object_id_list(), 'required': False})
 158                 return form_class(self.content_type.model_class()._default_manager.all(), **kwargs)
 159
 160         def apply_data(self, cleaned_data):
 161                 if 'value' in cleaned_data and cleaned_data['value'] is not None:
 162                         self.value = cleaned_data['value']
 163                 else:
 164                         self.content_type = cleaned_data.get('content_type', None)
 165                         # If there is no value set in the cleaned data, clear the stored value.
 166                         self.value = []
 167
 168         class Meta:
 169                 app_label = 'philo'
 170
 171
 172 class Attribute(models.Model):
 173         entity_content_type = models.ForeignKey(ContentType, related_name='attribute_entity_set', verbose_name='Entity type')
 174         entity_object_id = models.PositiveIntegerField(verbose_name='Entity ID')
 175         entity = generic.GenericForeignKey('entity_content_type', 'entity_object_id')
 176
 177         value_content_type = models.ForeignKey(ContentType, related_name='attribute_value_set', limit_choices_to=attribute_value_limiter, verbose_name='Value type', null=True, blank=True)
 178         value_object_id = models.PositiveIntegerField(verbose_name='Value ID', null=True, blank=True)
 179         value = generic.GenericForeignKey('value_content_type', 'value_object_id')
 180
 181         key = models.CharField(max_length=255)
 182
 183         def __unicode__(self):
 184                 return u'"%s": %s' % (self.key, self.value)
 185
 186         class Meta:
 187                 app_label = 'philo'
 188                 unique_together = (('key', 'entity_content_type', 'entity_object_id'), ('value_content_type', 'value_object_id'))
 189
 190
 191 class QuerySetMapper(object, DictMixin):
 192         def __init__(self, queryset, passthrough=None):
 193                 self.queryset = queryset
 194                 self.passthrough = passthrough
 195
 196         def __getitem__(self, key):
 197                 try:
 198                         value = self.queryset.get(key__exact=key).value
 199                 except ObjectDoesNotExist:
 200                         if self.passthrough is not None:
 201                                 return self.passthrough.__getitem__(key)
 202                         raise KeyError
 203                 else:
 204                         if value is not None:
 205                                 return value.value
 206                         return value
 207
 208         def keys(self):
 209                 keys = set(self.queryset.values_list('key', flat=True).distinct())
 210                 if self.passthrough is not None:
 211                         keys |= set(self.passthrough.keys())
 212                 return list(keys)
 213
 214
 215 class EntityOptions(object):
 216         def __init__(self, options):
 217                 if options is not None:
 218                         for key, value in options.__dict__.items():
 219                                 setattr(self, key, value)
 220                 if not hasattr(self, 'proxy_fields'):
 221                         self.proxy_fields = []
 222
 223         def add_proxy_field(self, proxy_field):
 224                 self.proxy_fields.append(proxy_field)
 225
 226
 227 class EntityBase(models.base.ModelBase):
 228         def __new__(cls, name, bases, attrs):
 229                 new = super(EntityBase, cls).__new__(cls, name, bases, attrs)
 230                 entity_options = attrs.pop('EntityMeta', None)
 231                 setattr(new, '_entity_meta', EntityOptions(entity_options))
 232                 entity_class_prepared.send(sender=new)
 233                 return new
 234
 235
 236 class Entity(models.Model):
 237         __metaclass__ = EntityBase
 238
 239         attribute_set = generic.GenericRelation(Attribute, content_type_field='entity_content_type', object_id_field='entity_object_id')
 240
 241         @property
 242         def attributes(self):
 243                 return QuerySetMapper(self.attribute_set.all())
 244
 245         @property
 246         def _added_attribute_registry(self):
 247                 if not hasattr(self, '_real_added_attribute_registry'):
 248                         self._real_added_attribute_registry = {}
 249                 return self._real_added_attribute_registry
 250
 251         @property
 252         def _removed_attribute_registry(self):
 253                 if not hasattr(self, '_real_removed_attribute_registry'):
 254                         self._real_removed_attribute_registry = []
 255                 return self._real_removed_attribute_registry
 256
 257         def save(self, *args, **kwargs):
 258                 super(Entity, self).save(*args, **kwargs)
 259
 260                 for key in self._removed_attribute_registry:
 261                         self.attribute_set.filter(key__exact=key).delete()
 262                 del self._removed_attribute_registry[:]
 263
 264                 for field, value in self._added_attribute_registry.items():
 265                         try:
 266                                 attribute = self.attribute_set.get(key__exact=field.key)
 267                         except Attribute.DoesNotExist:
 268                                 attribute = Attribute()
 269                                 attribute.entity = self
 270                                 attribute.key = field.key
 271
 272                         field.set_attribute_value(attribute, value)
 273                         attribute.save()
 274                 self._added_attribute_registry.clear()
 275
 276         class Meta:
 277                 abstract = True
 278
 279
 280 class TreeManager(models.Manager):
 281         use_for_related_fields = True
 282
 283         def get_with_path(self, path, root=None, absolute_result=True, pathsep='/', field='slug'):
 284                 """
 285                 Returns the object with the path, unless absolute_result is set to False, in which
 286                 case it returns a tuple containing the deepest object found along the path, and the
 287                 remainder of the path after that object as a string (or None if there is no remaining
 288                 path). Raises a DoesNotExist exception if no object is found with the given path.
 289
 290                 If the path you're searching for is known to exist, it is always faster to use
 291                 absolute_result=True - unless the path depth is over ~40, in which case the high cost
 292                 of the absolute query makes a binary search (i.e. non-absolute) faster.
 293                 """
 294                 # Note: SQLite allows max of 64 tables in one join. That means the binary search will
 295                 # only work on paths with a max depth of 127 and the absolute fetch will only work
 296                 # to a max depth of (surprise!) 63. Although this could be handled, chances are your
 297                 # tree structure won't be that deep.
 298                 segments = path.split(pathsep)
 299
 300                 # Check for a trailing pathsep so we can restore it later.
 301                 trailing_pathsep = False
 302                 if segments[-1] == '':
 303                         trailing_pathsep = True
 304
 305                 # Clean out blank segments. Handles multiple consecutive pathseps.
 306                 while True:
 307                         try:
 308                                 segments.remove('')
 309                         except ValueError:
 310                                 break
 311
 312                 # Special-case a lack of segments. No queries necessary.
 313                 if not segments:
 314                         if root is not None:
 315                                 if absolute_result:
 316                                         return root
 317                                 return root, None
 318                         else:
 319                                 raise self.model.DoesNotExist('%s matching query does not exist.' % self.model._meta.object_name)
 320
 321                 def make_query_kwargs(segments, root):
 322                         kwargs = {}
 323                         prefix = ""
 324                         revsegs = list(segments)
 325                         revsegs.reverse()
 326
 327                         for segment in revsegs:
 328                                 kwargs["%s%s__exact" % (prefix, field)] = segment
 329                                 prefix += "parent__"
 330
 331                         if prefix:
 332                                 kwargs[prefix[:-2]] = root
 333
 334                         return kwargs
 335
 336                 def build_path(segments):
 337                         path = pathsep.join(segments)
 338                         if trailing_pathsep and segments and segments[-1] != '':
 339                                 path += pathsep
 340                         return path
 341
 342                 def find_obj(segments, depth, deepest_found=None):
 343                         if deepest_found is None:
 344                                 deepest_level = 0
 345                         elif root is None:
 346                                 deepest_level = deepest_found.get_level() + 1
 347                         else:
 348                                 deepest_level = deepest_found.get_level() - root.get_level()
 349                         try:
 350                                 obj = self.get(**make_query_kwargs(segments[deepest_level:depth], deepest_found or root))
 351                         except self.model.DoesNotExist:
 352                                 if not deepest_level and depth > 1:
 353                                         # make sure there's a root node...
 354                                         depth = 1
 355                                 else:
 356                                         # Try finding one with half the path since the deepest find.
 357                                         depth = (deepest_level + depth)/2
 358
 359                                 if deepest_level == depth:
 360                                         # This should happen if nothing is found with any part of the given path.
 361                                         raise
 362
 363                                 return find_obj(segments, depth, deepest_found)
 364                         else:
 365                                 # Yay! Found one!
 366                                 if root is None:
 367                                         deepest_level = obj.get_level() + 1
 368                                 else:
 369                                         deepest_level = obj.get_level() - root.get_level()
 370
 371                                 # Could there be a deeper one?
 372                                 if obj.is_leaf_node():
 373                                         return obj, build_path(segments[deepest_level:]) or None
 374
 375                                 depth += (len(segments) - depth)/2 or len(segments) - depth
 376
 377                                 if depth > deepest_level + obj.get_descendant_count():
 378                                         depth = deepest_level + obj.get_descendant_count()
 379
 380                                 if deepest_level == depth:
 381                                         return obj, build_path(segments[deepest_level:]) or None
 382
 383                                 try:
 384                                         return find_obj(segments, depth, obj)
 385                                 except self.model.DoesNotExist:
 386                                         # Then this was the deepest.
 387                                         return obj, build_path(segments[deepest_level:])
 388
 389                 if absolute_result:
 390                         return self.get(**make_query_kwargs(segments, root))
 391
 392                 # Try a modified binary search algorithm. Feed the root in so that query complexity
 393                 # can be reduced. It might be possible to weight the search towards the beginning
 394                 # of the path, since short paths are more likely, but how far forward? It would
 395                 # need to shift depending on len(segments) - perhaps logarithmically?
 396                 return find_obj(segments, len(segments)/2 or len(segments))
 397
 398
 399 class TreeModel(MPTTModel):
 400         objects = TreeManager()
 401         parent = models.ForeignKey('self', related_name='children', null=True, blank=True)
 402         slug = models.SlugField(max_length=255)
 403
 404         def get_path(self, root=None, pathsep='/', field='slug'):
 405                 if root == self:
 406                         return ''
 407
 408                 if root is not None and not self.is_descendant_of(root):
 409                         raise AncestorDoesNotExist(root)
 410
 411                 qs = self.get_ancestors()
 412
 413                 if root is not None:
 414                         qs = qs.filter(level__gt=root.level)
 415
 416                 return pathsep.join([getattr(parent, field, '?') for parent in list(qs) + [self]])
 417         path = property(get_path)
 418
 419         def __unicode__(self):
 420                 return self.path
 421
 422         class Meta:
 423                 unique_together = (('parent', 'slug'),)
 424                 abstract = True
 425
 426
 427 class TreeEntityBase(MPTTModelBase, EntityBase):
 428         def __new__(meta, name, bases, attrs):
 429                 attrs['_mptt_meta'] = MPTTOptions(attrs.pop('MPTTMeta', None))
 430                 cls = EntityBase.__new__(meta, name, bases, attrs)
 431
 432                 return meta.register(cls)
 433
 434
 435 class TreeEntity(Entity, TreeModel):
 436         __metaclass__ = TreeEntityBase
 437
 438         @property
 439         def attributes(self):
 440                 if self.parent:
 441                         return QuerySetMapper(self.attribute_set.all(), passthrough=self.parent.attributes)
 442                 return super(TreeEntity, self).attributes
 443
 444         class Meta:
 445                 abstract = True