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