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 UserDict import DictMixin
   8
   9
  10 class Tag(models.Model):
  11         name = models.CharField(max_length=250)
  12         slug = models.SlugField(unique=True)
  13
  14         def __unicode__(self):
  15                 return self.name
  16
  17         class Meta:
  18                 app_label = 'philo'
  19
  20
  21 class Titled(models.Model):
  22         title = models.CharField(max_length=255)
  23         slug = models.SlugField(max_length=255)
  24
  25         def __unicode__(self):
  26                 return self.title
  27
  28         class Meta:
  29                 abstract = True
  30
  31
  32 class Attribute(models.Model):
  33         entity_content_type = models.ForeignKey(ContentType, verbose_name='Entity type')
  34         entity_object_id = models.PositiveIntegerField(verbose_name='Entity ID')
  35         entity = generic.GenericForeignKey('entity_content_type', 'entity_object_id')
  36         key = models.CharField(max_length=255)
  37         json_value = models.TextField(verbose_name='Value (JSON)', help_text='This value must be valid JSON.')
  38
  39         def get_value(self):
  40                 return json.loads(self.json_value)
  41
  42         def set_value(self, value):
  43                 self.json_value = json.dumps(value)
  44
  45         def delete_value(self):
  46                 self.json_value = json.dumps(None)
  47
  48         value = property(get_value, set_value, delete_value)
  49
  50         def __unicode__(self):
  51                 return u'"%s": %s' % (self.key, self.value)
  52
  53         class Meta:
  54                 app_label = 'philo'
  55                 unique_together = ('key', 'entity_content_type', 'entity_object_id')
  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')
  76         value_object_id = models.PositiveIntegerField(verbose_name='Value ID')
  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                 unique_together = ('key', 'entity_content_type', 'entity_object_id')
  85
  86
  87 class QuerySetMapper(object, DictMixin):
  88         def __init__(self, queryset, passthrough=None):
  89                 self.queryset = queryset
  90                 self.passthrough = passthrough
  91
  92         def __getitem__(self, key):
  93                 try:
  94                         return self.queryset.get(key__exact=key).value
  95                 except ObjectDoesNotExist:
  96                         if self.passthrough is not None:
  97                                 return self.passthrough.__getitem__(key)
  98                         raise KeyError
  99
 100         def keys(self):
 101                 keys = set(self.queryset.values_list('key', flat=True).distinct())
 102                 if self.passthrough is not None:
 103                         keys |= set(self.passthrough.keys())
 104                 return list(keys)
 105
 106
 107 class Entity(models.Model):
 108         attribute_set = generic.GenericRelation(Attribute, content_type_field='entity_content_type', object_id_field='entity_object_id')
 109         relationship_set = generic.GenericRelation(Relationship, content_type_field='entity_content_type', object_id_field='entity_object_id')
 110
 111         @property
 112         def attributes(self):
 113                 return QuerySetMapper(self.attribute_set)
 114
 115         @property
 116         def relationships(self):
 117                 return QuerySetMapper(self.relationship_set)
 118
 119         class Meta:
 120                 abstract = True
 121
 122
 123 class TreeManager(models.Manager):
 124         use_for_related_fields = True
 125
 126         def roots(self):
 127                 return self.filter(parent__isnull=True)
 128
 129         def get_with_path(self, path, root=None, absolute_result=True, pathsep='/'):
 130                 """
 131                 Returns the object with the path, or None if there is no object with that path,
 132                 unless absolute_result is set to False, in which case it returns a tuple containing
 133                 the deepest object found along the path, and the remainder of the path after that
 134                 object as a string (or None in the case that there is no remaining path).
 135                 """
 136                 slugs = path.split(pathsep)
 137                 obj = root
 138                 remaining_slugs = list(slugs)
 139                 remainder = None
 140                 for slug in slugs:
 141                         remaining_slugs.remove(slug)
 142                         if slug: # ignore blank slugs, handles for multiple consecutive pathseps
 143                                 try:
 144                                         obj = self.get(slug__exact=slug, parent__exact=obj)
 145                                 except self.model.DoesNotExist:
 146                                         if absolute_result:
 147                                                 obj = None
 148                                         remaining_slugs.insert(0, slug)
 149                                         remainder = pathsep.join(remaining_slugs)
 150                                         break
 151                 if obj:
 152                         if absolute_result:
 153                                 return obj
 154                         else:
 155                                 return (obj, remainder)
 156                 raise self.model.DoesNotExist('%s matching query does not exist.' % self.model._meta.object_name)
 157
 158
 159 class TreeModel(models.Model):
 160         objects = TreeManager()
 161         parent = models.ForeignKey('self', related_name='children', null=True, blank=True)
 162         slug = models.SlugField()
 163
 164         def has_ancestor(self, ancestor):
 165                 parent = self
 166                 while parent:
 167                         if parent == ancestor:
 168                                 return True
 169                         parent = parent.parent
 170                 return False
 171
 172         def get_path(self, root=None, pathsep='/', field='slug'):
 173                 if root is not None and self.has_ancestor(root):
 174                         path = ''
 175                         parent = self
 176                         while parent and parent != root:
 177                                 path = getattr(parent, field, '?') + pathsep + path
 178                                 parent = parent.parent
 179                         return path
 180                 else:
 181                         path = getattr(self, field, '?')
 182                         parent = self.parent
 183                         while parent and parent != root:
 184                                 path = getattr(parent, field, '?') + pathsep + path
 185                                 parent = parent.parent
 186                         return path
 187         path = property(get_path)
 188
 189         def __unicode__(self):
 190                 return self.path
 191
 192         class Meta:
 193                 unique_together = (('parent', 'slug'),)
 194                 abstract = True
 195
 196
 197 class TreeEntity(TreeModel, Entity):
 198         @property
 199         def attributes(self):
 200                 if self.parent:
 201                         return QuerySetMapper(self.attribute_set, passthrough=self.parent.attributes)
 202                 return super(TreeEntity, self).attributes
 203
 204         @property
 205         def relationships(self):
 206                 if self.parent:
 207                         return QuerySetMapper(self.relationship_set, passthrough=self.parent.relationships)
 208                 return super(TreeEntity, self).relationships
 209
 210         class Meta:
 211                 abstract = True