diff options
Diffstat (limited to 'django/db')
| -rw-r--r-- | django/db/models/base.py | 19 | ||||
| -rw-r--r-- | django/db/models/loading.py | 12 | ||||
| -rw-r--r-- | django/db/models/query.py | 116 |
3 files changed, 122 insertions, 25 deletions
diff --git a/django/db/models/base.py b/django/db/models/base.py index a253f38f47..d7e2c299cc 100644 --- a/django/db/models/base.py +++ b/django/db/models/base.py @@ -10,7 +10,7 @@ from django.core import validators from django.core.exceptions import ObjectDoesNotExist, MultipleObjectsReturned, FieldError from django.db.models.fields import AutoField, ImageField, FieldDoesNotExist from django.db.models.fields.related import OneToOneRel, ManyToOneRel, OneToOneField -from django.db.models.query import delete_objects, Q +from django.db.models.query import delete_objects, Q, CollectedObjects from django.db.models.options import Options from django.db import connection, transaction from django.db.models import signals @@ -365,17 +365,16 @@ class Model(object): error_dict[f.name] = errors return error_dict - def _collect_sub_objects(self, seen_objs): + 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 will be in the format: - {model_class: {pk_val: obj, pk_val: obj, ...}, - model_class: {pk_val: obj, pk_val: obj, ...}, ...} + 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 pk_val in seen_objs.setdefault(self.__class__, {}): + if seen_objs.add(self.__class__, pk_val, self, parent, nullable): return - seen_objs.setdefault(self.__class__, {})[pk_val] = self for related in self._meta.get_all_related_objects(): rel_opts_name = related.get_accessor_name() @@ -385,16 +384,16 @@ class Model(object): except ObjectDoesNotExist: pass else: - sub_obj._collect_sub_objects(seen_objs) + 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) + sub_obj._collect_sub_objects(seen_objs, self.__class__, related.field.null) 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 = SortedDict() + seen_objs = CollectedObjects() self._collect_sub_objects(seen_objs) # Actually delete the objects diff --git a/django/db/models/loading.py b/django/db/models/loading.py index e62188adf7..6837e070ac 100644 --- a/django/db/models/loading.py +++ b/django/db/models/loading.py @@ -2,6 +2,8 @@ from django.conf import settings from django.core.exceptions import ImproperlyConfigured +from django.utils.datastructures import SortedDict + import sys import os import threading @@ -18,10 +20,10 @@ class AppCache(object): # http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/66531. __shared_state = dict( # Keys of app_store are the model modules for each application. - app_store = {}, + app_store = SortedDict(), # Mapping of app_labels to a dictionary of model names to model code. - app_models = {}, + app_models = SortedDict(), # Mapping of app_labels to errors raised when trying to import the app. app_errors = {}, @@ -133,7 +135,7 @@ class AppCache(object): """ self._populate() if app_mod: - return self.app_models.get(app_mod.__name__.split('.')[-2], {}).values() + return self.app_models.get(app_mod.__name__.split('.')[-2], SortedDict()).values() else: model_list = [] for app_entry in self.app_models.itervalues(): @@ -149,7 +151,7 @@ class AppCache(object): """ if seed_cache: self._populate() - return self.app_models.get(app_label, {}).get(model_name.lower()) + return self.app_models.get(app_label, SortedDict()).get(model_name.lower()) def register_models(self, app_label, *models): """ @@ -159,7 +161,7 @@ class AppCache(object): # Store as 'name: model' pair in a dictionary # in the app_models dictionary model_name = model._meta.object_name.lower() - model_dict = self.app_models.setdefault(app_label, {}) + model_dict = self.app_models.setdefault(app_label, SortedDict()) if model_name in model_dict: # The same model may be imported via different paths (e.g. # appname.models and project.appname.models). We use the source diff --git a/django/db/models/query.py b/django/db/models/query.py index fb6d116a6e..8714cffb7f 100644 --- a/django/db/models/query.py +++ b/django/db/models/query.py @@ -16,6 +16,92 @@ ITER_CHUNK_SIZE = CHUNK_SIZE # Pull into this namespace for backwards compatibility EmptyResultSet = sql.EmptyResultSet +class CyclicDependency(Exception): + pass + +class CollectedObjects(object): + """ + A container that stores keys and lists of values along with + remembering the parent objects for all the keys. + + This is used for the database object deletion routines so that we + can calculate the 'leaf' objects which should be deleted first. + """ + + def __init__(self): + self.data = {} + self.children = {} + + def add(self, model, pk, obj, parent_model, nullable=False): + """ + Adds an item. + model is the class of the object being added, + pk is the primary key, obj is the object itself, + parent_model is the model of the parent object + that this object was reached through, nullable should + be True if this relation is nullable. + + If the item already existed in the structure, + returns true, otherwise false. + """ + d = self.data.setdefault(model, SortedDict()) + retval = pk in d + d[pk] = obj + # Nullable relationships can be ignored -- they + # are nulled out before deleting, and therefore + # do not affect the order in which objects have + # to be deleted. + if parent_model is not None and not nullable: + self.children.setdefault(parent_model, []).append(model) + + return retval + + def __contains__(self, key): + return self.data.__contains__(key) + + def __getitem__(self, key): + return self.data[key] + + def __nonzero__(self): + return bool(self.data) + + def iteritems(self): + for k in self.ordered_keys(): + yield k, self[k] + + def items(self): + return list(self.iteritems()) + + def keys(self): + return self.ordered_keys() + + def ordered_keys(self): + """ + Returns the models in the order that they should be + dealth with i.e. models with no dependencies first. + """ + dealt_with = SortedDict() + # Start with items that have no children + models = self.data.keys() + while len(dealt_with) < len(models): + found = False + for model in models: + children = self.children.setdefault(model, []) + if len([c for c in children if c not in dealt_with]) == 0: + dealt_with[model] = None + found = True + if not found: + raise CyclicDependency("There is a cyclic dependency of items to be processed.") + + return dealt_with.keys() + + def unordered_keys(self): + """ + Fallback for the case where is a cyclic dependency but we + don't care. + """ + return self.data.keys() + class QuerySet(object): "Represents a lazy database lookup for a set of objects" def __init__(self, model=None, query=None): @@ -275,7 +361,7 @@ class QuerySet(object): while 1: # Collect all the objects to be deleted in this chunk, and all the # objects that are related to the objects that are to be deleted. - seen_objs = SortedDict() + seen_objs = CollectedObjects() for object in del_query[:CHUNK_SIZE]: object._collect_sub_objects(seen_objs) @@ -682,19 +768,27 @@ def delete_objects(seen_objs): Iterate through a list of seen classes, and remove any instances that are referred to. """ - ordered_classes = seen_objs.keys() - ordered_classes.reverse() + try: + ordered_classes = seen_objs.keys() + except CyclicDependency: + # if there is a cyclic dependency, we cannot in general delete + # the objects. However, if an appropriate transaction is set + # up, or if the database is lax enough, it will succeed. + # So for now, we go ahead and try anway. + ordered_classes = seen_objs.unordered_keys() + obj_pairs = {} for cls in ordered_classes: - seen_objs[cls] = seen_objs[cls].items() - seen_objs[cls].sort() + items = seen_objs[cls].items() + items.sort() + obj_pairs[cls] = items # Pre notify all instances to be deleted - for pk_val, instance in seen_objs[cls]: + for pk_val, instance in items: dispatcher.send(signal=signals.pre_delete, sender=cls, instance=instance) - pk_list = [pk for pk,instance in seen_objs[cls]] + pk_list = [pk for pk,instance in items] del_query = sql.DeleteQuery(cls, connection) del_query.delete_batch_related(pk_list) @@ -705,15 +799,17 @@ def delete_objects(seen_objs): # Now delete the actual data for cls in ordered_classes: - seen_objs[cls].reverse() - pk_list = [pk for pk,instance in seen_objs[cls]] + items = obj_pairs[cls] + items.reverse() + + pk_list = [pk for pk,instance in items] del_query = sql.DeleteQuery(cls, connection) del_query.delete_batch(pk_list) # Last cleanup; set NULLs where there once was a reference to the # object, NULL the primary key of the found objects, and perform # post-notification. - for pk_val, instance in seen_objs[cls]: + for pk_val, instance in items: for field in cls._meta.fields: if field.rel and field.null and field.rel.to in seen_objs: setattr(instance, field.attname, None) |