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
  56
  57 value_content_type_limiter = ContentTypeRegistryLimiter()
  58
  59
  60 def register_value_model(model):
  61         value_content_type_limiter.register_class(model)
  62
  63
  64 def unregister_value_model(model):
  65         value_content_type_limiter.unregister_class(model)
  66
  67
  68
  69 class Relationship(models.Model):
  70         entity_content_type = models.ForeignKey(ContentType, related_name='relationship_entity_set', verbose_name='Entity type')
  71         entity_object_id = models.PositiveIntegerField(verbose_name='Entity ID')
  72         entity = generic.GenericForeignKey('entity_content_type', 'entity_object_id')
  73         key = models.CharField(max_length=255)
  74         value_content_type = models.ForeignKey(ContentType, related_name='relationship_value_set', limit_choices_to=value_content_type_limiter, verbose_name='Value type')
  75         value_object_id = models.PositiveIntegerField(verbose_name='Value ID')
  76         value = generic.GenericForeignKey('value_content_type', 'value_object_id')
  77
  78         def __unicode__(self):
  79                 return u'"%s": %s' % (self.key, self.value)
  80
  81         class Meta:
  82                 app_label = 'philo'
  83
  84
  85 class QuerySetMapper(object, DictMixin):
  86         def __init__(self, queryset, passthrough=None):
  87                 self.queryset = queryset
  88                 self.passthrough = passthrough
  89
  90         def __getitem__(self, key):
  91                 try:
  92                         return self.queryset.get(key__exact=key).value
  93                 except ObjectDoesNotExist:
  94                         if self.passthrough is not None:
  95                                 return self.passthrough.__getitem__(key)
  96                         raise KeyError
  97
  98         def keys(self):
  99                 keys = set(self.queryset.values_list('key', flat=True).distinct())
 100                 if self.passthrough is not None:
 101                         keys |= set(self.passthrough.keys())
 102                 return list(keys)
 103
 104
 105 class Entity(models.Model):
 106         attribute_set = generic.GenericRelation(Attribute, content_type_field='entity_content_type', object_id_field='entity_object_id')
 107         relationship_set = generic.GenericRelation(Relationship, content_type_field='entity_content_type', object_id_field='entity_object_id')
 108
 109         @property
 110         def attributes(self):
 111                 return QuerySetMapper(self.attribute_set)
 112
 113         @property
 114         def relationships(self):
 115                 return QuerySetMapper(self.relationship_set)
 116
 117         class Meta:
 118                 abstract = True
 119
 120
 121 class TreeManager(models.Manager):
 122         use_for_related_fields = True
 123
 124         def roots(self):
 125                 return self.filter(parent__isnull=True)
 126
 127         def get_with_path(self, path, root=None, absolute_result=True, pathsep='/'):
 128                 """
 129                 Returns the object with the path, or None if there is no object with that path,
 130                 unless absolute_result is set to False, in which case it returns a tuple containing
 131                 the deepest object found along the path, and the remainder of the path after that
 132                 object as a string (or None in the case that there is no remaining path).
 133                 """
 134                 slugs = path.split(pathsep)
 135                 obj = root
 136                 remaining_slugs = list(slugs)
 137                 remainder = None
 138                 for slug in slugs:
 139                         remaining_slugs.remove(slug)
 140                         if slug: # ignore blank slugs, handles for multiple consecutive pathseps
 141                                 try:
 142                                         obj = self.get(slug__exact=slug, parent__exact=obj)
 143                                 except self.model.DoesNotExist:
 144                                         if absolute_result:
 145                                                 obj = None
 146                                         remaining_slugs.insert(0, slug)
 147                                         remainder = pathsep.join(remaining_slugs)
 148                                         break
 149                 if obj:
 150                         if absolute_result:
 151                                 return obj
 152                         else:
 153                                 return (obj, remainder)
 154                 raise self.model.DoesNotExist('%s matching query does not exist.' % self.model._meta.object_name)
 155
 156
 157 class TreeModel(models.Model):
 158         objects = TreeManager()
 159         parent = models.ForeignKey('self', related_name='children', null=True, blank=True)
 160         slug = models.SlugField()
 161
 162         def get_path(self, pathsep='/', field='slug'):
 163                 path = getattr(self, field, '?')
 164                 parent = self.parent
 165                 while parent:
 166                         path = getattr(parent, field, '?') + pathsep + path
 167                         parent = parent.parent
 168                 return path
 169         path = property(get_path)
 170
 171         def __unicode__(self):
 172                 return self.path
 173
 174         class Meta:
 175                 unique_together = (('parent', 'slug'),)
 176                 abstract = True
 177
 178
 179 class TreeEntity(TreeModel, Entity):
 180         @property
 181         def attributes(self):
 182                 if self.parent:
 183                         return QuerySetMapper(self.attribute_set, passthrough=self.parent.attributes)
 184                 return super(TreeEntity, self).attributes
 185
 186         @property
 187         def relationships(self):
 188                 if self.parent:
 189                         return QuerySetMapper(self.relationship_set, passthrough=self.parent.relationships)
 190                 return super(TreeEntity, self).relationships
 191
 192         class Meta:
 193                 abstract = True