X-Git-Url: http://git.ithinksw.org/philo.git/blobdiff_plain/ed6b9876b7abff0b2dc6266d6f769c319f358a9c..54d1617957cfa3a8c9ffd714ad6c4bef09e727de:/philo/models/base.py?ds=sidebyside diff --git a/philo/models/base.py b/philo/models/base.py index af1e880..466b60a 100644 --- a/philo/models/base.py +++ b/philo/models/base.py @@ -1,18 +1,20 @@ +from UserDict import DictMixin + from django import forms -from django.db import models from django.contrib.contenttypes.models import ContentType from django.contrib.contenttypes import generic from django.core.exceptions import ObjectDoesNotExist from django.core.validators import RegexValidator +from django.db import models from django.utils import simplejson as json from django.utils.encoding import force_unicode +from mptt.models import MPTTModel, MPTTModelBase, MPTTOptions + from philo.exceptions import AncestorDoesNotExist from philo.models.fields import JSONField -from philo.utils import ContentTypeRegistryLimiter, ContentTypeSubclassLimiter from philo.signals import entity_class_prepared +from philo.utils import ContentTypeRegistryLimiter, ContentTypeSubclassLimiter from philo.validators import json_validator -from UserDict import DictMixin -from mptt.models import MPTTModel, MPTTModelBase, MPTTOptions class Tag(models.Model): @@ -38,10 +40,12 @@ class Titled(models.Model): abstract = True +#: An instance of :class:`ContentTypeRegistryLimiter` which is used to track the content types which can be related to by ForeignKeyValues and ManyToManyValues. value_content_type_limiter = ContentTypeRegistryLimiter() def register_value_model(model): + """Registers a model as a valid content type for a :class:`ForeignKeyValue` or :class:`ManyToManyValue` through the :data:`value_content_type_limiter`.""" value_content_type_limiter.register_class(model) @@ -49,21 +53,37 @@ register_value_model(Tag) def unregister_value_model(model): + """Registers a model as a valid content type for a :class:`ForeignKeyValue` or :class:`ManyToManyValue` through the :data:`value_content_type_limiter`.""" value_content_type_limiter.unregister_class(model) class AttributeValue(models.Model): + """ + This is an abstract base class for models that can be used as values for :class:`Attribute`\ s. + + AttributeValue subclasses are expected to supply access to a clean version of their value through an attribute called "value". + + """ + + #: :class:`GenericRelation` to :class:`Attribute` attribute_set = generic.GenericRelation('Attribute', content_type_field='value_content_type', object_id_field='value_object_id') def set_value(self, value): + """Given a ``value``, sets the appropriate fields so that it can be correctly stored in the database.""" raise NotImplementedError def value_formfields(self, **kwargs): - """Define any formfields that would be used to construct an instance of this value.""" + """ + Returns any formfields that would be used to construct an instance of this value. + + :returns: A dictionary mapping field names to formfields. + + """ + raise NotImplementedError def construct_instance(self, **kwargs): - """Apply cleaned data from the formfields generated by valid_formfields to oneself.""" + """Applies cleaned data from the formfields generated by valid_formfields to oneself.""" raise NotImplementedError def __unicode__(self): @@ -73,10 +93,12 @@ class AttributeValue(models.Model): abstract = True +#: An instance of :class:`ContentTypeSubclassLimiter` which is used to track the content types which are considered valid value models for an :class:`Attribute`. attribute_value_limiter = ContentTypeSubclassLimiter(AttributeValue) class JSONValue(AttributeValue): + """Stores a python object as a json string.""" value = JSONField(verbose_name='Value (JSON)', help_text='This value must be valid JSON.', default='null', db_index=True) def __unicode__(self): @@ -99,6 +121,7 @@ class JSONValue(AttributeValue): class ForeignKeyValue(AttributeValue): + """Stores a generic relationship to an instance of any value content type (as defined by the :data:`value_content_type_limiter`).""" content_type = models.ForeignKey(ContentType, limit_choices_to=value_content_type_limiter, verbose_name='Value type', null=True, blank=True) object_id = models.PositiveIntegerField(verbose_name='Value ID', null=True, blank=True, db_index=True) value = generic.GenericForeignKey() @@ -136,6 +159,7 @@ class ForeignKeyValue(AttributeValue): class ManyToManyValue(AttributeValue): + """Stores a generic relationship to many instances of any value content type (as defined by the :data:`value_content_type_limiter`).""" content_type = models.ForeignKey(ContentType, limit_choices_to=value_content_type_limiter, verbose_name='Value type', null=True, blank=True) values = models.ManyToManyField(ForeignKeyValue, blank=True, null=True) @@ -215,14 +239,20 @@ class ManyToManyValue(AttributeValue): class Attribute(models.Model): + """Represents an arbitrary key/value pair on an arbitrary :class:`Model` where the key consists of word characters and the value is a subclass of :class:`AttributeValue`.""" entity_content_type = models.ForeignKey(ContentType, related_name='attribute_entity_set', verbose_name='Entity type') entity_object_id = models.PositiveIntegerField(verbose_name='Entity ID', db_index=True) + + #: :class:`GenericForeignKey` to anything (generally an instance of an Entity subclass). entity = generic.GenericForeignKey('entity_content_type', 'entity_object_id') 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) value_object_id = models.PositiveIntegerField(verbose_name='Value ID', null=True, blank=True, db_index=True) + + #: :class:`GenericForeignKey` to an instance of a subclass of :class:`AttributeValue` as determined by the :data:`attribute_value_limiter`. value = generic.GenericForeignKey('value_content_type', 'value_object_id') + #: :class:`CharField` containing a key (up to 255 characters) consisting of alphanumeric characters and underscores. key = models.CharField(max_length=255, validators=[RegexValidator("\w+")], help_text="Must contain one or more alphanumeric characters or underscores.", db_index=True) def __unicode__(self): @@ -279,12 +309,26 @@ class EntityBase(models.base.ModelBase): class Entity(models.Model): + """An abstract class that simplifies access to related attributes. Most models provided by Philo subclass Entity.""" __metaclass__ = EntityBase attribute_set = generic.GenericRelation(Attribute, content_type_field='entity_content_type', object_id_field='entity_object_id') @property def attributes(self): + """ + Property that returns a dictionary-like object which can be used to retrieve related :class:`Attribute`\ s' values directly. + + Example:: + + >>> attr = entity.attribute_set.get(key='spam') + >>> attr.value.value + u'eggs' + >>> entity.attributes['spam'] + u'eggs' + + """ + return QuerySetMapper(self.attribute_set.all()) class Meta: @@ -296,19 +340,21 @@ class TreeManager(models.Manager): def get_with_path(self, path, root=None, absolute_result=True, pathsep='/', field='slug'): """ - Returns the object with the path, unless absolute_result is set to False, in which - case it returns a tuple containing the deepest object found along the path, and the - remainder of the path after that object as a string (or None if there is no remaining - path). Raises a DoesNotExist exception if no object is found with the given path. - - If the path you're searching for is known to exist, it is always faster to use - absolute_result=True - unless the path depth is over ~40, in which case the high cost - of the absolute query makes a binary search (i.e. non-absolute) faster. + If ``absolute_result`` is ``True``, returns the object at ``path`` (starting at ``root``) or raises a :exception:`DoesNotExist` exception. Otherwise, returns a tuple containing the deepest object found along ``path`` (or ``root`` if no deeper object is found) and the remainder of the path after that object as a string (or None if there is no remaining path). + + .. note:: If you are looking for something with an exact path, it is faster to use absolute_result=True, unless the path depth is over ~40, in which case the high cost of the absolute query may make a binary search (i.e. non-absolute) faster. + + .. note:: SQLite allows max of 64 tables in one join. That means the binary search will only work on paths with a max depth of 127 and the absolute fetch will only work to a max depth of (surprise!) 63. Larger depths could be handled, but since the common use case will not have a tree structure that deep, they are not. + + :param path: The path of the object + :param root: The object which will be considered the root of the search + :param absolute_result: Whether to return an absolute result or do a binary search + :param pathsep: The path separator used in ``path`` + :param field: The field on the model which should be queried for ``path`` segment matching. + :returns: An instance if absolute_result is True or (instance, remaining_path) otherwise. + """ - # Note: SQLite allows max of 64 tables in one join. That means the binary search will - # only work on paths with a max depth of 127 and the absolute fetch will only work - # to a max depth of (surprise!) 63. Although this could be handled, chances are your - # tree structure won't be that deep. + segments = path.split(pathsep) # Clean out blank segments. Handles multiple consecutive pathseps. @@ -407,6 +453,14 @@ class TreeModel(MPTTModel): slug = models.SlugField(max_length=255) def get_path(self, root=None, pathsep='/', field='slug'): + """ + :param root: Only return the path since this object. + :param pathsep: The path separator to use when constructing an instance's path + :param field: The field to pull path information from for each ancestor. + :returns: A string representation of an object's path. + + """ + if root == self: return '' @@ -438,10 +492,27 @@ class TreeEntityBase(MPTTModelBase, EntityBase): class TreeEntity(Entity, TreeModel): + """An abstract subclass of Entity which represents a tree relationship.""" + __metaclass__ = TreeEntityBase @property def attributes(self): + """ + Property that returns a dictionary-like object which can be used to retrieve related :class:`Attribute`\ s' values directly. If an attribute with a given key is not related to the :class:`Entity`, then the object will check the parent's attributes. + + Example:: + + >>> attr = entity.attribute_set.get(key='spam') + DoesNotExist: Attribute matching query does not exist. + >>> attr = entity.parent.attribute_set.get(key='spam') + >>> attr.value.value + u'eggs' + >>> entity.attributes['spam'] + u'eggs' + + """ + if self.parent: return QuerySetMapper(self.attribute_set.all(), passthrough=self.parent.attributes) return super(TreeEntity, self).attributes