import copy
import types
import sys
import os
from itertools import izip
try:
set
except NameError:
from sets import Set as set # Python 2.3 fallback.
import django.db.models.manager # Imported to register signal handler.
from django.core.exceptions import ObjectDoesNotExist, MultipleObjectsReturned, FieldError
from django.db.models.fields import AutoField
from django.db.models.fields.related import OneToOneRel, ManyToOneRel, OneToOneField
from django.db.models.query import delete_objects, Q, CollectedObjects
from django.db.models.options import Options
from django.db import connection, transaction, DatabaseError
from django.db.models import signals
from django.db.models.loading import register_models, get_model
from django.utils.functional import curry
from django.utils.encoding import smart_str, force_unicode, smart_unicode
from django.conf import settings
class ModelBase(type):
"""
Metaclass for all models.
"""
def __new__(cls, name, bases, attrs):
super_new = super(ModelBase, cls).__new__
parents = [b for b in bases if isinstance(b, ModelBase)]
if not parents:
# If this isn't a subclass of Model, don't do anything special.
return super_new(cls, name, bases, attrs)
# Create the class.
module = attrs.pop('__module__')
new_class = super_new(cls, name, bases, {'__module__': module})
attr_meta = attrs.pop('Meta', None)
abstract = getattr(attr_meta, 'abstract', False)
if not attr_meta:
meta = getattr(new_class, 'Meta', None)
else:
meta = attr_meta
base_meta = getattr(new_class, '_meta', None)
if getattr(meta, 'app_label', None) is None:
# Figure out the app_label by looking one level up.
# For 'django.contrib.sites.models', this would be 'sites'.
model_module = sys.modules[new_class.__module__]
kwargs = {"app_label": model_module.__name__.split('.')[-2]}
else:
kwargs = {}
new_class.add_to_class('_meta', Options(meta, **kwargs))
if not abstract:
new_class.add_to_class('DoesNotExist',
subclass_exception('DoesNotExist', ObjectDoesNotExist, module))
new_class.add_to_class('MultipleObjectsReturned',
subclass_exception('MultipleObjectsReturned', MultipleObjectsReturned, module))
if base_meta and not base_meta.abstract:
# Non-abstract child classes inherit some attributes from their
# non-abstract parent (unless an ABC comes before it in the
# method resolution order).
if not hasattr(meta, 'ordering'):
new_class._meta.ordering = base_meta.ordering
if not hasattr(meta, 'get_latest_by'):
new_class._meta.get_latest_by = base_meta.get_latest_by
if getattr(new_class, '_default_manager', None):
new_class._default_manager = None
# Bail out early if we have already created this class.
m = get_model(new_class._meta.app_label, name, False)
if m is not None:
return m
# Add all attributes to the class.
for obj_name, obj in attrs.items():
new_class.add_to_class(obj_name, obj)
# Do the appropriate setup for any model parents.
o2o_map = dict([(f.rel.to, f) for f in new_class._meta.local_fields
if isinstance(f, OneToOneField)])
for base in parents:
if not hasattr(base, '_meta'):
# Things without _meta aren't functional models, so they're
# uninteresting parents.
continue
# All the fields of any type declared on this model
new_fields = new_class._meta.local_fields + \
new_class._meta.local_many_to_many + \
new_class._meta.virtual_fields
field_names = set([f.name for f in new_fields])
if not base._meta.abstract:
# Concrete classes...
if base in o2o_map:
field = o2o_map[base]
field.primary_key = True
new_class._meta.setup_pk(field)
else:
attr_name = '%s_ptr' % base._meta.module_name
field = OneToOneField(base, name=attr_name,
auto_created=True, parent_link=True)
new_class.add_to_class(attr_name, field)
new_class._meta.parents[base] = field
else:
# .. and abstract ones.
# Check for clashes between locally declared fields and those
# on the ABC.
parent_fields = base._meta.local_fields + base._meta.local_many_to_many
for field in parent_fields:
if field.name in field_names:
raise FieldError('Local field %r in class %r clashes '\
'with field of similar name from '\
'abstract base class %r' % \
(field.name, name, base.__name__))
new_class.add_to_class(field.name, copy.deepcopy(field))
# Pass any non-abstract parent classes onto child.
new_class._meta.parents.update(base._meta.parents)
# Inherit managers from the abstract base classes.
base_managers = base._meta.abstract_managers
base_managers.sort()
for _, mgr_name, manager in base_managers:
val = getattr(new_class, mgr_name, None)
if not val or val is manager:
new_manager = manager._copy_to_model(new_class)
new_class.add_to_class(mgr_name, new_manager)
# Inherit virtual fields (like GenericForeignKey) from the parent class
for field in base._meta.virtual_fields:
if base._meta.abstract and field.name in field_names:
raise FieldError('Local field %r in class %r clashes '\
'with field of similar name from '\
'abstract base class %r' % \
(field.name, name, base.__name__))
new_class.add_to_class(field.name, copy.deepcopy(field))
if abstract:
# Abstract base models can't be instantiated and don't appear in
# the list of models for an app. We do the final setup for them a
# little differently from normal models.
attr_meta.abstract = False
new_class.Meta = attr_meta
return new_class
new_class._prepare()
register_models(new_class._meta.app_label, new_class)
# Because of the way imports happen (recursively), we may or may not be
# the first time this model tries to register with the framework. There
# should only be one class for each model, so we always return the
# registered version.
return get_model(new_class._meta.app_label, name, False)
def add_to_class(cls, name, value):
if hasattr(value, 'contribute_to_class'):
value.contribute_to_class(cls, name)
else:
setattr(cls, name, value)
def _prepare(cls):
"""
Creates some methods once self._meta has been populated.
"""
opts = cls._meta
opts._prepare(cls)
if opts.order_with_respect_to:
cls.get_next_in_order = curry(cls._get_next_or_previous_in_order, is_next=True)
cls.get_previous_in_order = curry(cls._get_next_or_previous_in_order, is_next=False)
setattr(opts.order_with_respect_to.rel.to, 'get_%s_order' % cls.__name__.lower(), curry(method_get_order, cls))
setattr(opts.order_with_respect_to.rel.to, 'set_%s_order' % cls.__name__.lower(), curry(method_set_order, cls))
# Give the class a docstring -- its definition.
if cls.__doc__ is None:
cls.__doc__ = "%s(%s)" % (cls.__name__, ", ".join([f.attname for f in opts.fields]))
if hasattr(cls, 'get_absolute_url'):
cls.get_absolute_url = curry(get_absolute_url, opts, cls.get_absolute_url)
signals.class_prepared.send(sender=cls)
class Model(object):
__metaclass__ = ModelBase
def __init__(self, *args, **kwargs):
signals.pre_init.send(sender=self.__class__, args=args, kwargs=kwargs)
# There is a rather weird disparity here; if kwargs, it's set, then args
# overrides it. It should be one or the other; don't duplicate the work
# The reason for the kwargs check is that standard iterator passes in by
# args, and instantiation for iteration is 33% faster.
args_len = len(args)
if args_len > len(self._meta.fields):
# Daft, but matches old exception sans the err msg.
raise IndexError("Number of args exceeds number of fields")
fields_iter = iter(self._meta.fields)
if not kwargs:
# The ordering of the izip calls matter - izip throws StopIteration
# when an iter throws it. So if the first iter throws it, the second
# is *not* consumed. We rely on this, so don't change the order
# without changing the logic.
for val, field in izip(args, fields_iter):
setattr(self, field.attname, val)
else:
# Slower, kwargs-ready version.
for val, field in izip(args, fields_iter):
setattr(self, field.attname, val)
kwargs.pop(field.name, None)
# Maintain compatibility with existing calls.
if isinstance(field.rel, ManyToOneRel):
kwargs.pop(field.attname, None)
# Now we're left with the unprocessed fields that *must* come from
# keywords, or default.
for field in fields_iter:
rel_obj = None
if kwargs:
if isinstance(field.rel, ManyToOneRel):
try:
# Assume object instance was passed in.
rel_obj = kwargs.pop(field.name)
except KeyError:
try:
# Object instance wasn't passed in -- must be an ID.
val = kwargs.pop(field.attname)
except KeyError:
val = field.get_default()
else:
# Object instance was passed in. Special case: You can
# pass in "None" for related objects if it's allowed.
if rel_obj is None and field.null:
val = None
else:
val = kwargs.pop(field.attname, field.get_default())
else:
val = field.get_default()
# If we got passed a related instance, set it using the field.name
# instead of field.attname (e.g. "user" instead of "user_id") so
# that the object gets properly cached (and type checked) by the
# RelatedObjectDescriptor.
if rel_obj:
setattr(self, field.name, rel_obj)
else:
setattr(self, field.attname, val)
if kwargs:
for prop in kwargs.keys():
try:
if isinstance(getattr(self.__class__, prop), property):
setattr(self, prop, kwargs.pop(prop))
except AttributeError:
pass
if kwargs:
raise TypeError, "'%s' is an invalid keyword argument for this function" % kwargs.keys()[0]
signals.post_init.send(sender=self.__class__, instance=self)
def __repr__(self):
return smart_str(u'<%s: %s>' % (self.__class__.__name__, unicode(self)))
def __str__(self):
if hasattr(self, '__unicode__'):
return force_unicode(self).encode('utf-8')
return '%s object' % self.__class__.__name__
def __eq__(self, other):
return isinstance(other, self.__class__) and self._get_pk_val() == other._get_pk_val()
def __ne__(self, other):
return not self.__eq__(other)
def __hash__(self):
return hash(self._get_pk_val())
def _get_pk_val(self, meta=None):
if not meta:
meta = self._meta
return getattr(self, meta.pk.attname)
def _set_pk_val(self, value):
return setattr(self, self._meta.pk.attname, value)
pk = property(_get_pk_val, _set_pk_val)
def save(self, force_insert=False, force_update=False):
"""
Saves the current instance. Override this in a subclass if you want to
control the saving process.
The 'force_insert' and 'force_update' parameters can be used to insist
that the "save" must be an SQL insert or update (or equivalent for
non-SQL backends), respectively. Normally, they should not be set.
"""
if force_insert and force_update:
raise ValueError("Cannot force both insert and updating in "
"model saving.")
self.save_base(force_insert=force_insert, force_update=force_update)
save.alters_data = True
def save_base(self, raw=False, cls=None, force_insert=False,
force_update=False):
"""
Does the heavy-lifting involved in saving. Subclasses shouldn't need to
override this method. It's separate from save() in order to hide the
need for overrides of save() to pass around internal-only parameters
('raw' and 'cls').
"""
assert not (force_insert and force_update)
if not cls:
cls = self.__class__
meta = self._meta
signal = True
signals.pre_save.send(sender=self.__class__, instance=self, raw=raw)
else:
meta = cls._meta
signal = False
# If we are in a raw save, save the object exactly as presented.
# That means that we don't try to be smart about saving attributes
# that might have come from the parent class - we just save the
# attributes we have been given to the class we have been given.
if not raw:
for parent, field in meta.parents.items():
# At this point, parent's primary key field may be unknown
# (for example, from administration form which doesn't fill
# this field). If so, fill it.
if getattr(self, parent._meta.pk.attname) is None and getattr(self, field.attname) is not None:
setattr(self, parent._meta.pk.attname, getattr(self, field.attname))
self.save_base(raw, parent)
setattr(self, field.attname, self._get_pk_val(parent._meta))
non_pks = [f for f in meta.local_fields if not f.primary_key]
# First, try an UPDATE. If that doesn't update anything, do an INSERT.
pk_val = self._get_pk_val(meta)
pk_set = pk_val is not None
record_exists = True
manager = cls._default_manager
if pk_set:
# Determine whether a record with the primary key already exists.
if (force_update or (not force_insert and
manager.filter(pk=pk_val).extra(select={'a': 1}).values('a').order_by())):
# It does already exist, so do an UPDATE.
if force_update or non_pks:
values = [(f, None, f.get_db_prep_save(raw and getattr(self, f.attname) or f.pre_save(self, False))) for f in non_pks]
rows = manager.filter(pk=pk_val)._update(values)
if force_update and not rows:
raise DatabaseError("Forced update did not affect any rows.")
else:
record_exists = False
if not pk_set or not record_exists:
if not pk_set:
if force_update:
raise ValueError("Cannot force an update in save() with no primary key.")
values = [(f, f.get_db_prep_save(raw and getattr(self, f.attname) or f.pre_save(self, True))) for f in meta.local_fields if not isinstance(f, AutoField)]
else:
values = [(f, f.get_db_prep_save(raw and getattr(self, f.attname) or f.pre_save(self, True))) for f in meta.local_fields]
if meta.order_with_respect_to:
field = meta.order_with_respect_to
values.append((meta.get_field_by_name('_order')[0], manager.filter(**{field.name: getattr(self, field.attname)}).count()))
record_exists = False
update_pk = bool(meta.has_auto_field and not pk_set)
if values:
# Create a new record.
result = manager._insert(values, return_id=update_pk)
else:
# Create a new record with defaults for everything.
result = manager._insert([(meta.pk, connection.ops.pk_default_value())], return_id=update_pk, raw_values=True)
if update_pk:
setattr(self, meta.pk.attname, result)
transaction.commit_unless_managed()
if signal:
signals.post_save.send(sender=self.__class__, instance=self,
created=(not record_exists), raw=raw)
save_base.alters_data = True
def _collect_sub_objects(self, seen_objs, parent=None, nullable=False):
"""
Recursively populates seen_objs with all objects related to this
object.
When done, seen_objs.items() will be in the format:
[(model_class, {pk_val: obj, pk_val: obj, ...}),
(model_class, {pk_val: obj, pk_val: obj, ...}), ...]
"""
pk_val = self._get_pk_val()
if seen_objs.add(self.__class__, pk_val, self, parent, nullable):
return
for related in self._meta.get_all_related_objects():
rel_opts_name = related.get_accessor_name()
if isinstance(related.field.rel, OneToOneRel):
try:
sub_obj = getattr(self, rel_opts_name)
except ObjectDoesNotExist:
pass
else:
sub_obj._collect_sub_objects(seen_objs, self.__class__, related.field.null)
else:
for sub_obj in getattr(self, rel_opts_name).all():
sub_obj._collect_sub_objects(seen_objs, self.__class__, related.field.null)
# Handle any ancestors (for the model-inheritance case). We do this by
# traversing to the most remote parent classes -- those with no parents
# themselves -- and then adding those instances to the collection. That
# will include all the child instances down to "self".
parent_stack = self._meta.parents.values()
while parent_stack:
link = parent_stack.pop()
parent_obj = getattr(self, link.name)
if parent_obj._meta.parents:
parent_stack.extend(parent_obj._meta.parents.values())
continue
# At this point, parent_obj is base class (no ancestor models). So
# delete it and all its descendents.
parent_obj._collect_sub_objects(seen_objs)
def delete(self):
assert self._get_pk_val() is not None, "%s object can't be deleted because its %s attribute is set to None." % (self._meta.object_name, self._meta.pk.attname)
# Find all the objects than need to be deleted.
seen_objs = CollectedObjects()
self._collect_sub_objects(seen_objs)
# Actually delete the objects.
delete_objects(seen_objs)
delete.alters_data = True
def _get_FIELD_display(self, field):
value = getattr(self, field.attname)
return force_unicode(dict(field.flatchoices).get(value, value), strings_only=True)
def _get_next_or_previous_by_FIELD(self, field, is_next, **kwargs):
op = is_next and 'gt' or 'lt'
order = not is_next and '-' or ''
param = smart_str(getattr(self, field.attname))
q = Q(**{'%s__%s' % (field.name, op): param})
q = q|Q(**{field.name: param, 'pk__%s' % op: self.pk})
qs = self.__class__._default_manager.filter(**kwargs).filter(q).order_by('%s%s' % (order, field.name), '%spk' % order)
try:
return qs[0]
except IndexError:
raise self.DoesNotExist, "%s matching query does not exist." % self.__class__._meta.object_name
def _get_next_or_previous_in_order(self, is_next):
cachename = "__%s_order_cache" % is_next
if not hasattr(self, cachename):
qn = connection.ops.quote_name
op = is_next and '>' or '<'
order = not is_next and '-_order' or '_order'
order_field = self._meta.order_with_respect_to
# FIXME: When querysets support nested queries, this can be turned
# into a pure queryset operation.
where = ['%s %s (SELECT %s FROM %s WHERE %s=%%s)' % \
(qn('_order'), op, qn('_order'),
qn(self._meta.db_table), qn(self._meta.pk.column))]
params = [self.pk]
obj = self._default_manager.filter(**{order_field.name: getattr(self, order_field.attname)}).extra(where=where, params=params).order_by(order)[:1].get()
setattr(self, cachename, obj)
return getattr(self, cachename)
############################################
# HELPER FUNCTIONS (CURRIED MODEL METHODS) #
############################################
# ORDERING METHODS #########################
def method_set_order(ordered_obj, self, id_list):
rel_val = getattr(self, ordered_obj._meta.order_with_respect_to.rel.field_name)
order_name = ordered_obj._meta.order_with_respect_to.name
# FIXME: It would be nice if there was an "update many" version of update
# for situations like this.
for i, j in enumerate(id_list):
ordered_obj.objects.filter(**{'pk': j, order_name: rel_val}).update(_order=i)
transaction.commit_unless_managed()
def method_get_order(ordered_obj, self):
rel_val = getattr(self, ordered_obj._meta.order_with_respect_to.rel.field_name)
order_name = ordered_obj._meta.order_with_respect_to.name
pk_name = ordered_obj._meta.pk.name
return [r[pk_name] for r in
ordered_obj.objects.filter(**{order_name: rel_val}).values(pk_name)]
##############################################
# HELPER FUNCTIONS (CURRIED MODEL FUNCTIONS) #
##############################################
def get_absolute_url(opts, func, self, *args, **kwargs):
return settings.ABSOLUTE_URL_OVERRIDES.get('%s.%s' % (opts.app_label, opts.module_name), func)(self, *args, **kwargs)
########
# MISC #
########
class Empty(object):
pass
if sys.version_info < (2, 5):
# Prior to Python 2.5, Exception was an old-style class
def subclass_exception(name, parent, unused):
return types.ClassType(name, (parent,), {})
else:
def subclass_exception(name, parent, module):
return type(name, (parent,), {'__module__': module})