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.many_to_many + \ new_class._meta.virtual_fields field_names = set([f.name for f in new_fields]) # Concrete classes... if not base._meta.abstract: 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 # .. and abstract ones. else: # 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)) # 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})