X-Git-Url: http://git.ithinksw.org/philo.git/blobdiff_plain/cec32849d48d9e36c030224e2eb9631d31ef17a2..4fcb99e48c980dfa220d219a093745e58fdf5371:/philo/models/fields/entities.py diff --git a/philo/models/fields/entities.py b/philo/models/fields/entities.py index 6c407d0..cc8c398 100644 --- a/philo/models/fields/entities.py +++ b/philo/models/fields/entities.py @@ -1,29 +1,14 @@ -""" -The EntityProxyFields defined in this file can be assigned as fields on -a subclass of philo.models.Entity. They act like any other model -fields, but instead of saving their data to the database, they save it -to attributes related to a model instance. Additionally, a new -attribute will be created for an instance if and only if the field's -value has been set. This is relevant i.e. for passthroughs, where the -value of the field may be defined by some other instance's attributes. - -Example:: - - class Thing(Entity): - numbers = models.PositiveIntegerField() - - class ThingProxy(Thing): - improvised = JSONAttribute(models.BooleanField) -""" +import datetime from itertools import tee + from django import forms from django.core.exceptions import FieldError from django.db import models from django.db.models.fields import NOT_PROVIDED from django.utils.text import capfirst -from philo.signals import entity_class_prepared + from philo.models import ManyToManyValue, JSONValue, ForeignKeyValue, Attribute, Entity -import datetime +from philo.signals import entity_class_prepared __all__ = ('JSONAttribute', 'ForeignKeyAttribute', 'ManyToManyAttribute') @@ -32,8 +17,23 @@ __all__ = ('JSONAttribute', 'ForeignKeyAttribute', 'ManyToManyAttribute') ATTRIBUTE_REGISTRY = '_attribute_registry' -class EntityProxyField(object): - def __init__(self, verbose_name=None, help_text=None, default=NOT_PROVIDED, editable=True, choices=None, *args, **kwargs): +class AttributeProxyField(object): + """ + :class:`AttributeProxyField`\ s can be assigned as fields on a subclass of :class:`philo.models.base.Entity`. They act like any other model fields, but instead of saving their data to the model's table, they save it to :class:`.Attribute`\ s related to a model instance. Additionally, a new :class:`.Attribute` will be created for an instance if and only if the field's value has been set. This is relevant i.e. for :class:`.PassthroughAttributeMapper`\ s and :class:`.TreeAttributeMapper`\ s, where even an :class:`.Attribute` with a value of ``None`` will prevent a passthrough. + + Example:: + + class Thing(Entity): + numbers = models.PositiveIntegerField() + improvised = JSONAttribute(models.BooleanField) + + :param attribute_key: The key of the attribute that will be used to store this field's value, if it is different than the field's name. + + The remaining parameters have the same meaning as for ordinary model fields. + + """ + def __init__(self, attribute_key=None, verbose_name=None, help_text=None, default=NOT_PROVIDED, editable=True, choices=None, *args, **kwargs): + self.attribute_key = attribute_key self.verbose_name = verbose_name self.help_text = help_text self.default = default @@ -42,8 +42,15 @@ class EntityProxyField(object): def actually_contribute_to_class(self, sender, **kwargs): sender._entity_meta.add_proxy_field(self) + setattr(sender, self.name, AttributeFieldDescriptor(self)) + opts = sender._entity_meta + if not hasattr(opts, '_has_attribute_fields'): + opts._has_attribute_fields = True + models.signals.post_save.connect(process_attribute_fields, sender=sender) def contribute_to_class(self, cls, name): + if self.attribute_key is None: + self.attribute_key = name if issubclass(cls, Entity): self.name = self.attname = name self.model = cls @@ -54,6 +61,10 @@ class EntityProxyField(object): raise FieldError('%s instances can only be declared on Entity subclasses.' % self.__class__.__name__) def formfield(self, form_class=forms.CharField, **kwargs): + """ + Returns a form field capable of accepting values for the :class:`AttributeProxyField`. + + """ defaults = { 'required': False, 'label': capfirst(self.verbose_name), @@ -65,25 +76,34 @@ class EntityProxyField(object): return form_class(**defaults) def value_from_object(self, obj): - """The return value of this method will be used by the EntityForm as - this field's initial value.""" + """Returns the value of this field in the given model instance.""" return getattr(obj, self.name) def get_storage_value(self, value): - """Final conversion of `value` before it gets stored on an Entity instance. - This step is performed by the ProxyFieldForm.""" + """Final conversion of ``value`` before it gets stored on an :class:`.Entity` instance. This will be called during :meth:`.EntityForm.save`.""" return value + def validate_value(self, value): + "Raise an appropriate exception if ``value`` is not valid for this :class:`AttributeProxyField`." + pass + def has_default(self): + """Returns ``True`` if a default value was provided and ``False`` otherwise.""" return self.default is not NOT_PROVIDED def _get_choices(self): + """Returns the choices passed into the constructor.""" if hasattr(self._choices, 'next'): choices, self._choices = tee(self._choices) return choices else: return self._choices choices = property(_get_choices) + + @property + def value_class(self): + """Each :class:`AttributeProxyField` subclass can define a value_class to use for creation of new :class:`.AttributeValue`\ s""" + raise AttributeError("value_class must be defined on %s subclasses." % self.__class__.__name__) class AttributeFieldDescriptor(object): @@ -124,62 +144,32 @@ class AttributeFieldDescriptor(object): def process_attribute_fields(sender, instance, created, **kwargs): + """This function is attached to each :class:`Entity` subclass's post_save signal. Any :class:`Attribute`\ s managed by :class:`AttributeProxyField`\ s which have been removed will be deleted, and any new attributes will be created.""" if ATTRIBUTE_REGISTRY in instance.__dict__: registry = instance.__dict__[ATTRIBUTE_REGISTRY] instance.attribute_set.filter(key__in=[field.attribute_key for field in registry['removed']]).delete() for field in registry['added']: + # TODO: Should this perhaps just use instance.attributes[field.attribute_key] = getattr(instance, field.name, None)? + # (Would eliminate the need for field.value_class.) try: attribute = instance.attribute_set.get(key=field.attribute_key) except Attribute.DoesNotExist: attribute = Attribute() attribute.entity = instance attribute.key = field.attribute_key - - value_class = field.value_class - if isinstance(attribute.value, value_class): - value = attribute.value - else: - if isinstance(attribute.value, models.Model): - attribute.value.delete() - value = value_class() - - value.set_value(getattr(instance, field.name, None)) - value.save() - - attribute.value = value - attribute.save() + attribute.set_value(value=getattr(instance, field.name, None), value_class=field.value_class) del instance.__dict__[ATTRIBUTE_REGISTRY] -class AttributeField(EntityProxyField): - def __init__(self, attribute_key=None, **kwargs): - self.attribute_key = attribute_key - super(AttributeField, self).__init__(**kwargs) +class JSONAttribute(AttributeProxyField): + """ + Handles an :class:`.Attribute` with a :class:`.JSONValue`. - def actually_contribute_to_class(self, sender, **kwargs): - super(AttributeField, self).actually_contribute_to_class(sender, **kwargs) - setattr(sender, self.name, AttributeFieldDescriptor(self)) - opts = sender._entity_meta - if not hasattr(opts, '_has_attribute_fields'): - opts._has_attribute_fields = True - models.signals.post_save.connect(process_attribute_fields, sender=sender) + :param field_template: A django form field instance that will be used to guide rendering and interpret values. For example, using :class:`django.forms.BooleanField` will make this field render as a checkbox. - def contribute_to_class(self, cls, name): - if self.attribute_key is None: - self.attribute_key = name - super(AttributeField, self).contribute_to_class(cls, name) - - def validate_value(self, value): - "Confirm that the value is valid or raise an appropriate error." - pass + """ - @property - def value_class(self): - raise AttributeError("value_class must be defined on AttributeField subclasses.") - - -class JSONAttribute(AttributeField): value_class = JSONValue def __init__(self, field_template=None, **kwargs): @@ -200,12 +190,14 @@ class JSONAttribute(AttributeField): return self.field_template.formfield(**defaults) def value_from_object(self, obj): + """If the field template is a :class:`DateField` or a :class:`DateTimeField`, this will convert the default return value to a datetime instance.""" value = super(JSONAttribute, self).value_from_object(obj) if isinstance(self.field_template, (models.DateField, models.DateTimeField)): value = self.field_template.to_python(value) return value def get_storage_value(self, value): + """If ``value`` is a :class:`datetime.datetime` instance, this will convert it to a format which can be stored as correct JSON.""" if isinstance(value, datetime.datetime): return value.strftime("%Y-%m-%d %H:%M:%S") if isinstance(value, datetime.date): @@ -213,11 +205,18 @@ class JSONAttribute(AttributeField): return value -class ForeignKeyAttribute(AttributeField): +class ForeignKeyAttribute(AttributeProxyField): + """ + Handles an :class:`.Attribute` with a :class:`.ForeignKeyValue`. + + :param limit_choices_to: A :class:`Q` object, dictionary, or :class:`.ContentTypeLimiter` to restrict the queryset for the :class:`ForeignKeyAttribute`. + + """ value_class = ForeignKeyValue def __init__(self, model, limit_choices_to=None, **kwargs): super(ForeignKeyAttribute, self).__init__(**kwargs) + # Spoof being a rel from a ForeignKey for admin widgets. self.to = model if limit_choices_to is None: limit_choices_to = {} @@ -235,15 +234,22 @@ class ForeignKeyAttribute(AttributeField): return super(ForeignKeyAttribute, self).formfield(form_class=form_class, **defaults) def value_from_object(self, obj): + """Converts the default value type (a model instance) to a pk.""" relobj = super(ForeignKeyAttribute, self).value_from_object(obj) return getattr(relobj, 'pk', None) def get_related_field(self): - """Spoof being a rel from a ForeignKey.""" + # Spoof being a rel from a ForeignKey for admin widgets. return self.to._meta.pk class ManyToManyAttribute(ForeignKeyAttribute): + """ + Handles an :class:`.Attribute` with a :class:`.ManyToManyValue`. + + :param limit_choices_to: A :class:`Q` object, dictionary, or :class:`ContentTypeLimiter ` to restrict the queryset for the :class:`ManyToManyAttribute`. + + """ value_class = ManyToManyValue def validate_value(self, value): @@ -254,6 +260,7 @@ class ManyToManyAttribute(ForeignKeyAttribute): return super(ManyToManyAttribute, self).formfield(form_class=form_class, **kwargs) def value_from_object(self, obj): + """Converts the default value type (a queryset) to a list of pks.""" qs = super(ForeignKeyAttribute, self).value_from_object(obj) try: return qs.values_list('pk', flat=True)