Django snippets

# This Python file uses the following encoding: utf-8
import os, sys
import datetime
from tempfile import mkstemp
from django.conf import settings
from django.db import models, connection
from django.db.models import signals
from django.db.models.fields import AutoField, DateTimeField, DateField, TimeField, FieldDoesNotExist
from django.db.models.fields.related import ForeignKey, OneToOneField, ManyToManyField
from django.dispatch import dispatcher

def hash_dict(dictionary):
    return hash(frozenset(dictionary.items()))
        
class BulkInsert(models.Manager):
    """ BulkInsert Manager Class
        contact kgoudeaux@gmail.com
        
        Public Interface:
        bulk_insert(self, now=None, raw=False, send_pre_save=True, **kwargs):
        bulk_insert_commit(self, now=None, autoclobber=False, max_depth=5, send_post_save=True, **kwargs)
        bulk_insert_now(self, now=None)
        bulk_insert_threshold(self, threshold=1000)
        
        Update 5-9-2008 Added support for self references for Foreign Keys, 
                        OneToOne Fields and Many to Many relations
                        max_depth default changed to 5
        
        Tested on Django SVN 7519
        Currently, only MySQL is supported although a crude framework is there to support others
        
        Bulk insert objects to a database including Foreign Key, One to One and Many to Many
        relationships.
        
        You can also create self referential relationships of each type including (non)symmetrical
        Many to Many relationships.
        
        Insert an object by calling bulk_insert(kwargs) where kwargs is what you would specify
        to create an instance of the underlying model i.e. Model(kwargs).
        
        Field names in kwargs can also include any related names declared on other models.
        
        IMPORTANT: Internally, because no primary keys are known until the objects are inserted,
        each object is identified by its "kwargs signature" which is a hash of the field names
        and values given to bulk_insert combined with any pre_computed default values.
        
        If you want to insert the _exact_ same data in a bunch of rows, this won't help you.
        Objects with the same signature will be treated as if they are the same
        object.
        
        If you specify your own primary key values when the primary key is an AutoField,
        your values will be ignored
        
        #####################
        #      Example      #
        #####################
        Given these three classes:
        
        class Author(models.Model):
            first_name = models.CharField(blank=True, max_length=100)
            last_name = models.CharField(blank=True, max_length=100)

        class Article(models.Model):
            author = models.ForeignKey(Author, null=True)
            text = models.CharField(blank=True, max_length=100, default='')
            objects = BulkInsert()
        
        class Note(models.Model):
            article = models.ForeignKey(Article, related_name='notes')
            text = models.CharField(blank=True, max_length=100)

        class Character(models.Model):
            char = models.CharField(blank=True, max_length=1)
            words = models.ManyToManyField(Article, related_name='characters')
        
        1. Article.objects.bulk_insert( text="this is gibberish", 
                                        author={'first_name':'John', 'last_name':'Smith}
                                        notes=[{'text':'very long'}, {'text':'very short'}],
                                        characters=[{'chars':'t'}, {'chars':'h'}, {'chars':'i'}, {'chars':'s'},
                                                    {'chars':' '}, {'chars':'i'}, {'chars':'s'}, {'chars':' '},
                                                    {'chars':'g'}, {'chars':'i'}, {'chars':'b'}, {'chars':'b'},
                                                    {'chars':'e'}, {'chars':'r'}, {'chars':'i'}, {'chars':'s'},
                                                    {'chars':'h'}])
        2. Article.objects.bulk_insert( text="this is gibberish",
                                        author={'first_name':'John', 'last_name':'Smith})
                                        
        3. Article.objects.bulk_insert( text="this is gibberish",
                                        author={'first_name':'John', 'last_name':'Smith},
                                        notes=Note(text="just right"))
                                        
        Article.objects.bulk_insert_commit()
        
        On commit, the effect of the first call will be to first bulk insert an Author object and recover its primary key.
        Then it will insert the Article object referencing the Author object and recover the Article's primary key
        Next it will insert two notes and associate them with the Article
        Finally it will bulk insert all of the characters and establish each character's many_to_many
        relationship with the Article
        
        Note that there are duplicate Character objects being added, the duplicates will all be treated as
        the same object as their "kwargs signatures" are identical
        
        Also note that the second call to bulk insert will NOT create another article object because its
        kwargs signature matches the first call.  Only fields stored in the Article's table are used to compute
        the signature
        
        The third call to bulk_insert will add an additional note. Notice that it's a Note object
        with an unset primary key.  It will be converted into a set of kwargs and bulk inserted accordingly.
        If its primary key were set, the key would be extracted to set the relationships but the object would
        not be re-inserted
        
        For this example, the pre_save signal will be called *three* times for the Article object and post_save
        will be called once
        
        #####################
        #    Real Example   #
        #####################
        Saving related search terms from the Yahoo.jp API in a general
        WebQuery table. A maximum of 100 related terms are retrieved at a time
        
        class WebQuery(models.Model):
            query = models.CharField(blank=False, null=False, max_length=256)
            query_type = models.IntegerField(blank=False, null=False, choices=QUERY_TYPES)
            ...
            class Meta:
                unique_together = ("query", "query_type")
            
        class RelatedSearch(models.Model):
            original = models.CharField(blank=True, max_length=100, unique=True)
            queries = models.ManyToManyField(WebQuery, related_name='searches')
            ...

            objects = BulkInsert()
        
        Without bulk insert
        -------------------
        queries = []
        r = RelatedSearch.objects.get_or_create(original=original_query)
        for q in get_related_searches(original_query):
            webquery = WebQuery.objects.get_or_create(query=q, query_type=YAHOOJP_RELATED)
            queries.append(webquery.id)
        r.queries.add(*queries)
            
        Worst Case: 101 objects are inserted using 204 db queries       
        
        With Bulk Insert
        ----------------
        queries = []
        for q in get_related_searches(original_query):
            queries.append({'query': q, 'query_type': YAHOOJP_RELATED})
        RelatedSearch.objects.bulk_insert(original=original_query, queries=queries)
        RelatedSearch.objects.bulk_insert_commit()
        
        Worst Case: 101 objects are inserted with 6 db queries

        #####################
        #       Notes       #
        #####################
        Arguments to bulk_insert can include the underlying models fields, of course, but also
        any related name specified by a related class.  In other words you can treat relationships
        defined on other models as "fields" on this model, similar to QuerySets.
        
        If the object you wish to specify a relationship with doesn't exist, simply provide a
        dict of arguments or a model instance with an unset primary key and it will be queued and
        bulk inserted accordingly.
        
        You don't need to add BulkInsert as a manager to each class you wish to perform bulk
        inserts with - just the class you want to perform bulk inserts _relative to_.
        
        If, when bulk inserting a list of related objects, it cannot find a BulkInsert manager,
        it will add one to that class and perform the insert
        
        To execute the actual insert call bulk_insert_commit.
        
        This will execute the insert using an INSERT statement or by bulk loading into the
        database from a temp file.  A default threshold of 1000 must be met before the insert
        is performed from a file.
        
        For the file insert to work, write permissions are needed in the current working directory
        or settings.BULK_INSERT_DIR
        
        Also, the mysql user needs file priveleges i.e:
          GRANT FILE ON *.* TO 'user'@'localhost';
        Note that for MySQL, File permissions can only be added globally
        
        Regardless of the number of objects and type of relationships, this will make
        1 database call to perform the insert per table affected and N/100 calls per table
        to recover primary keys where N is the number of rows to be inserted
        
        Generic Foreign Keys Partially Supported - Need a fix like Ticket #5826
        Currently generic foreign keys can only be set by manually specifying the content_type and object_id
        
        Whereas on a model instance with a GFK, you can do something like: 
            instance.element = object
        instead of:
            instance.content_type = ContentType.objects.get_for_model(object.__class__)
            instance.object_id = object.id
            
        There currently isn't a way to recover from the GFK object, the field names that it points to.
        So the convenient form of:
            Model.objects.bulk_insert(element={'name': 'Jim'}) isn't possible
        use:
            Create and save Jim object and collect its id
            Model.objects.bulk_insert(content_type=ctype, object_id=id)
        
        #####################
        #      Gotchas      #
        #####################
        -- data types - For MySQL, TEXT and BLOB types cannot be inserted with LOAD DATA INSERT
        To insure that the file insert isn't used, specify a negative threshold for
        bulk_insert_threshold()
        
        -- pre_save signal - It's very possible that pre_save will be called more than once
        for the same object when inserting a lot of objects or adding a lot of relationships
        
        e.g.  If you are programmatically generating values and bulk_insert object A. Presave
        will be called.  If you bulk insert A again with many_to_many relationship B. Presave 
        will be called again.
        
        If this is undesirable, specify send_pre_save = False when calling bulk_insert()
        
        --In a pre_save function, all changes to instance values will be recorded, however, be
        careful with computations that produce different results based on time.  If pre_save is
        called three times for what is nominally the same object and three different values are
        set, they will be treated as 3 different objects.
        
        If this is undesirable, specify send_pre_save = False when calling bulk_insert()
        
        -- DateTime, Date, and Time fields - If using datetime.now as your default value,
        one value for "now" is precomputed and used for all inserts i.e. every date or time
        field that uses datetime.now or auto_now or auto_now_add will have the same value
        
        Think of them as all being inserted at the same instant
        
        -- Default values that call a function.  If you compute a dynamic default value, know
        that it will be computed once and cached for all inserted objects
        
        #####################
        #   Self Reference  #
        #####################
        Self References operate the same as any other reference but there are some powerful
        gotchas if you get too creative.  This doesn't handle the *general* case of limitless
        recursive relationships.  If you start seeing warnings and KeyErrors, simplify your inserts.
        
        Symmetrical is honored for self referencing m2m fields.  The direction of relationships can be
        bulk inserted by specifiying the m2m field name or the related name.
        
        In the example below, this is done by setting 'friends' or 'followers'
        
        Given this class loaded with self references:
        class Player(models.Model):
            first_name = models.CharField(blank=True, max_length=100)
            last_name = models.CharField(blank=True, max_length=100)

            friends = models.ManyToManyField('self', symmetrical=False, related_name='followers', null=True)
            favorite = models.ForeignKey('self', related_name='fans', null=True)
            antiself = models.OneToOneField('self', related_name='realme', null=True)

            objects = BulkInsert()

        And this set of dicts representing players and their relationships:
        other_players = [{'first_name':"Babe", 'last_name':'Ruth', 
                                'friends': [{'first_name': 'Cal', 'last_name': 'Ripkin'},
                                            {'first_name': 'Willie', 'last_name': 'Mays'}]}, 
                        {'first_name':"Hank", 'last_name':'Aaron'}]
        players = [ {'first_name':'Mark', 'last_name':'McGuire', 'followers':other_players},
                                'antiself': {'first_name': 'Willie', 'last_name': 'Mays'},
                    {'first_name':'Sammy', 'last_name':'Sosa', 'favorite':{'first_name':'Hank', 'last_name':'Aaron'}},
                    {'first_name':'Johnny', 'last_name':'Bench', 'antiself':{'first_name':'Hank', 'last_name':'Aaron'}},
                    {'first_name': 'Mickey', 'last_name': 'Mantle', 'friends': other_players}]
                    
        for player in players:
            GibberishAuthor.objects.bulk_insert(**player)
        GibberishAuthor.objects.bulk_insert_commit()
        
        This is a contorted example that pushes the limits but in its unnecessary complexity, shows what can be done.
        After commit, a total of *8* unique players will be added:
        
        Babe Ruth       favorite:None   antiself:None   friends:3 [Cal Ripkin, Willie Mays, Mark McGuire]
        Cal Ripkin      favorite:None   antiself:None   friends:0 []
        Willie Mays     favorite:None   antiself:None   friends:0 []
        Hank Aaron      favorite:None   antiself:None   friends:1 [Mark McGuire]
        Mark McGuire    favorite:None   antiself:Willie friends:0 []
        Sammy Sosa      favorite:Hank   antiself:None   friends:0 []
        Johnny Bench    favorite:None   antiself:Hank   friends:0 []
        Mickey Mantle   favorite:None   antiself:None   friends:2 [Babe Ruth, Hank Aaron]
        
        The first thing to note is that even though some players are referenced more than once,
        their kwargs signatures (hash of all non-m2m field values) are identical.
        
        Be careful with self referential fk and one2one relations that are nested below the first level.
        Note that fk's and one2one's were set in 'players' but not in 'other_players'.  Inserting fk and
        one2one self references breaks the one insert per table design of this manager because fk's and one2one's
        must be inserted first.  To deeply nest self referential fk's and one2one's, use objects whose primary
        key is already set or just provide the primary key value directly.
        
        To do this on the nested many to many relations above:
        other_players = [{'first_name':"Babe", 'last_name':'Ruth', 'friends': [ 
                                {'first_name': 'Cal', 'last_name': 'Ripkin'},
                                {'first_name': 'Willie', 'last_name': 'Mays'}],
                ------->            'favorite': Player.objects.create(first_name='Bob', last_name='Jones'), 
                ------->            'antiself': 3},
                        {'first_name':"Hank", 'last_name':'Aaron'}]
                        
        If you can, avoid deeply nesting self references or provide model instances with primary keys.
        Because the kwargs signature is the only unique identifier, you may unwittingly create two
        versions of the same object or worse, it will error out on a KeyError because some distant
        self reference changed the kwargs signature of the object.
        
        You'll probably never need to do something so twisted, but if you do, those are the caveats.
        
    """
    def __init__(self):
        super(models.Manager, self).__init__()
        self.queue = {}
        self.order = {}
        #Special Handlers for Self Referencing Objects
        self.ref_queue = {}
        self.ref_order = {}
        self.ref_cache = {}
        
        self.related_fields = {}
        self.related_queue = {}
        self.related_classes = {}
        
        self.m2one_queue = {}
        self.m2one_fields = {}
        self.m2one_classes = {}

        self.m2m_queue = {}
        self.m2m_fields = {}
        self.m2m_classes = {}
        
        self.update_map = {}
        self.defaults = {}

        self.initialized = False
        self.now = datetime.datetime.now()
        
        if settings.DATABASE_ENGINE == 'mysql':
            self.backend = MySQL_BulkInsert()
        else:
            #dummy backend - does nothing
            self.backend = BulkInsertBackend()
        self.threshold = 1000
    def bulk_insert_now(self, now=None):
        if now is not None:
            self.now = now
        else:
            self.now = datetime.datetime.now()
            
        #Some default values may be invalidated by changing 'now'
        if self.initialized:
            self._collect_field_defaults()
        else:
            self._related_init()
    def bulk_insert_threshold(self, threshold=1000):
        self.threshold = threshold
    def bulk_insert(self, now=None, raw=False, clean_args=False, send_pre_save=True, _self_ref=False, **kwargs):
        """
        Hold kwargs in queue until bulk_insert_commit
        
        All field preprocessing is done unless raw=True
        Returns a hash for kwargs if clean_args=True
          Primarily for internal use
        Sends pre_save signal unless send_pre_save=False
        
        kwargs can include any field from the underlying model including any related_name's
        specified by related models
        
        """
        if not self.initialized:
            #Initialize is delayed until bulk_insert is first called to ensure
            #that all relationship hooks have been added to the underlying class
            self._related_init()
            self.tempModel = self.model()
            
        if now is not None:
            if now != self.now:
                self.now = now
                self._collect_field_defaults()
        
        #check for valid field names
        self._check_fields(kwargs=kwargs)
        
        #Determine which related fields are present
        fk_or_one2one = set(kwargs.keys()).intersection(set(self.related_fields.keys()))
        many_to_one = set(kwargs.keys()).intersection(set(self.m2one_fields.keys()))
        many_to_many = set(kwargs.keys()).intersection(set(self.m2m_fields.keys()))
        
        #pop off m2m and m2one names, the tempModel can't handle them
        m2m_dict = {}
        for name in many_to_many:
            m2m_dict[name] = kwargs.pop(name)
            
        m2one_dict = {}
        for name in many_to_one:
            m2one_dict[name] = kwargs.pop(name)
        
        #Pop off Foreign Key and OneToOne names if they need to be bulk inserted first
        related = []
        for name in fk_or_one2one:
            if isinstance(kwargs[name], dict):
                manager = self._find_bulk_manager(self.related_classes[name])
                sref = self.related_classes[name] == self.model
                arg_hash = manager.bulk_insert(now=self.now, clean_args=True, _self_ref=sref, **kwargs[name])
                related += [(name, arg_hash)]

                kwargs.pop(name)
            elif isinstance(kwargs[name], self.related_classes[name]) and getattr(kwargs[name], kwargs[name]._meta.pk.attname) is None:
                args = self._generate_args(kwargs[name])
                manager = self._find_bulk_manager(self.related_classes[name])
                sref = self.related_classes[name] == self.model
                arg_hash = manager.bulk_insert(now=self.now, clean_args=True, _self_ref=sref, **args)
                related += [(name, arg_hash)]

                kwargs.pop(name)
                
            
        #Temporary model for signal dispatch and field preprocessing
        #self.tempModel = self.model()
        for name in kwargs.keys():
            field = self.tempModel._meta.get_field(name)
            if isinstance(field, ForeignKey) and isinstance(kwargs[name], int) or isinstance(kwargs[name], long):
                setattr(self.tempModel, field.attname, kwargs[name])
                continue
            setattr(self.tempModel, field.name, kwargs[name])
                    
        #Preprocess field data unless 'raw' specified on call
        #Special handling for defaults on date and time fields to ensure
        #proper formatting for primary key recovery
        watch = {}
        for f in self.tempModel._meta.fields:
            val = getattr(self.tempModel, f.attname)
            watch[f.name] = val
            if isinstance(f, AutoField):
                if f.name in kwargs.keys():
                    kwargs[f.name] = f.get_db_prep_save(raw and val or f.pre_save(self.tempModel, True))
            elif f.name in kwargs.keys():
                kwargs[f.name] = f.get_db_prep_save(raw and val or f.pre_save(self.tempModel, True))
            else:
                kwargs[f.name] = self.defaults[f.name]
                
        #Presave could be called more than once for the same object
        if send_pre_save:
            dispatcher.send(signal=signals.pre_save, sender=self.tempModel.__class__, instance=self.tempModel)
            
        #Check for changes from pre_save
        for f in [field for field in self.tempModel._meta.fields if field.name in kwargs]:
            if watch[f.name] != getattr(self.tempModel, f.attname):
                kwargs[f.name] = f.get_db_prep_save(raw and val or f.pre_save(self.tempModel, True))

        #hash to identify this arg:value set
        key = hash_dict(kwargs)
        
        #Objects with the same arg:value signature are considered
        #the same object
        if _self_ref:
            if key not in self.ref_queue:
                self.ref_queue[key] = kwargs
                self.ref_order[key] = len(self.ref_queue)
        elif key not in self.queue:
            self.queue[key] = kwargs
            self.order[key] = len(self.queue)
                
        #With the key computed, associate it with any Fk's and one2one's
        #that will be inserted later
        for name, arg_hash in related:
            if arg_hash not in self.related_queue[name]:
                self.related_queue[name][arg_hash] = []
            self.related_queue[name][arg_hash] += [key]
            
        for name in many_to_one:
            self._m2one_enqueue(name, m2one_dict[name], key)
                
        for name in many_to_many:
            self._m2m_enqueue(name, m2m_dict[name], key)
        
        #tempModel = None
        self._clear_tempModel()
        if clean_args:
            return key
    def _clear_tempModel(self):
        for field in self.tempModel._meta.fields:
            val = field.get_default()
            setattr(self.tempModel, field.attname, val)
            
    def bulk_insert_commit(self, now=None, autoclobber=False, depth=0, max_depth=5, send_post_save=True, _self_ref=False, **kwargs):
        """
        Bulk inserts all queued objects and relations to the database with one insert per affected table
        and N/100 selects to find the primary keys where N is the number of inserted rows
        
        If autoclobber is False, the default, the insert is performed with IGNORE.  Any object that duplicates one
        already in the database is not reinserted but any new relationships will be
        
        if autoclobber is True, the insert is performed with REPLACE, clobbering any duplicates

        If autoclobber is None, no checking is done and any duplicates will raise a Database Integrity Error
        
        If kwargs is specified, its values are used to overide any model defaults
        """
        if not self.queue or depth > max_depth:
            return {}
            
        self._check_fields(no_related=True, kwargs=kwargs)

        many_to_many = filter(lambda x: x['list'] != [], self.m2m_queue.values()) != []
        many_to_one = filter(lambda x: x != [], self.m2one_queue.values()) != []
        related = filter(lambda x: x != [], self.related_queue.values()) != []
        
        m2m_depth = filter(lambda x: x['bulk'], self.m2m_queue.values())
        try:
            if not _self_ref:
                #Foreign Key and OneToOne are inserted first
                #Their primary keys are needed to save the root objects
                if related:
                    self._fk_one2one_insert(depth, max_depth, autoclobber)
        
                    #inserting a fk or one2one invalidates our kwargs signatures
                    #computing new hashes and mapping to the old hash for m2m and m2one
                    copy = {}
                    order_copy = {}
                    self.update_map = {}
                    for key, value in self.queue.items():
                        new_key = hash_dict(value)
                        self.update_map[key] = new_key
                        copy[new_key] = value
                        try:
                            order_copy[new_key] = self.order[key]
                        except KeyError:
                            #For nested inserts with self references, objects
                            #inserted across those references have no order information
                            order_copy[new_key] = sys.maxint
                    self.queue = copy
                    self.order = order_copy
        
        
                order = self.order.items()
                order.sort(lambda x,y: x[1] - y[1])
            else:
                #Related Self References are bunched together and inserted once
                #however, commit will be called for every self referencing field
                #If the commit has already been done, return the cached queue
                if not self.ref_queue:
                    return self.ref_cache, self.update_map
                order = self.ref_order.items()
                order.sort(lambda x,y: x[1] - y[1])
        
            #Saving the root objects
            queue = _self_ref and self.ref_queue or self.queue
            if len(queue) <= self.threshold or self.threshold < 0:
                self.backend.insert(table=self.model._meta.db_table,
                                    fields=[f for f in self.model._meta.fields if not isinstance(f, AutoField)],
                                    queue=queue,
                                    order = order,
                                    autoclobber=autoclobber)
            else:
                self.backend.write_temp_file(fields=[f for f in self.model._meta.fields if not isinstance(f, AutoField)],
                                            queue=queue)

                self.backend.insert_from_file(table=self.model._meta.db_table, 
                                            columns=[f.column for f in self.model._meta.fields if not isinstance(f, AutoField)], 
                                            autoclobber=autoclobber)
                                

            self._recover_pks(_self_ref)
    
            if not _self_ref:
                if many_to_many:
                    self._many_to_many_insert(depth, max_depth, autoclobber)
                if many_to_one:
                    self._many_to_one_insert(depth, max_depth, autoclobber)
                
        except Exception, e:
            self.reset()
            raise Exception, e
            
        #Dispatch Post Save Signals
        if send_post_save:
            values = _self_ref and self.ref_queue.values() or self.queue.values()
            for args in values:
                for name in args.keys():
                    setattr(self.tempModel, self.tempModel._meta.get_field(name).attname, args[name])
                dispatcher.send(signal=signals.post_save, sender=self.tempModel.__class__, instance=self.tempModel)
                self._clear_tempModel()
            
        if depth > 0:
            queue = dict(_self_ref and self.ref_queue or self.queue)
            update_map = self.update_map
            self.reset(_self_ref)
            if _self_ref:
                self.ref_cache = queue
            return queue, update_map
        self.reset()
        return {}, {}
        
    def reset(self, _self_ref=False):
        """
        Close and remove any temp files
        Reset all queues and field maps
        """
        if _self_ref:
            self.ref_queue = {}
            self.ref_order = {}
            self.backend.clear()
            return
            
        self.queue = {}
        self.ref_queue = {}
        for key in self.m2one_queue.keys():
            self.m2one_queue[key] = []
        for key in self.m2m_queue.keys():
            self.m2m_queue[key] = {'list':[], 'bulk':False}
        for key in self.related_queue.keys():
            self.related_queue[key] = {}
        self.update_map = {}
        self.order = {}
        self.ref_order = {}
        self.ref_cache = {}
        self.backend.clear()
        
    ###################
    # PRIVATE METHODS #
    ###################
    def _related_init(self):
        """
        Find all related forward and reverse Foreign Key, OneToOne,
        ManyToMany and ManyToOne relationships and cache the relevant
        fields and model classes
        """
        self.initialized = True
        for f in self.model._meta.fields:
            if isinstance(f, ForeignKey) or isinstance(f, OneToOneField):
                self.related_classes[f.name] = f.rel.to
                self.related_fields[f.name] = f
                self.related_queue[f.name] = {}

        for r in self.model._meta.get_all_related_objects():
            name = r.field.rel.related_name or r.model.__name__.lower() + '_set'
            self.m2one_classes[name] = r.model
            self.m2one_fields[name] = r.field
            self.m2one_queue[name] = []
            
        for f in self.model._meta.many_to_many:
            self.m2m_classes[f.name] = f.rel.to
            self.m2m_fields[f.name] = f
            self.m2m_queue[f.name] = {'list':[], 'bulk':False}
            
        for m2m in self.model._meta.get_all_related_many_to_many_objects():
            name = m2m.field.rel.related_name or m2m.model.__name__.lower() + '_set'
            self.m2m_classes[name] = m2m.model
            self.m2m_fields[name] = m2m.field
            self.m2m_queue[name] = {'list':[], 'bulk':False}
            
        self._collect_field_defaults()
        
    def _collect_field_defaults(self):
        """
        Collect default values for each field
        """
        self.defaults = {}
        scrapModel = self.model()
        for f in scrapModel._meta.fields:
            if isinstance(f, DateTimeField) or isinstance(f, DateField) or isinstance(f, TimeField):
                if (f.default == datetime.datetime.now or f.auto_now or f.auto_now_add):
                    if isinstance(f, DateTimeField):
                        self.defaults[f.name] = self.now.strftime('%Y-%m-%d %H:%M:%S')
                    elif isinstance(f, DateField):
                        self.defaults[f.name] = self.now.strftime('%Y-%m-%d')
                    elif isinstance(f, TimeField):
                        self.defaults[f.name] = self.now.strftime('%H:%M:%S')
                    continue
            if not isinstance(f, AutoField):
                self.defaults[f.name] = scrapModel._meta.get_field(f.name).get_db_prep_save(f.pre_save(scrapModel, True))
                
    def _check_fields(self, no_related=False, kwargs={}):
        """
        Check that all fields given to bulk_insert and bulk_insert_commit are valid
        """
        if no_related:
            valid_fields = set([f.name for f in self.model._meta.fields])
        else:
            valid_fields = set([f.name for f in self.model._meta.fields] + self.m2m_fields.keys() + self.m2one_fields.keys())
        invalid_fields = set(kwargs.keys()) - valid_fields

        assert len(invalid_fields) == 0, \
                    "Invalid field(s): %s . Acceptable field values: %s . All Arguments: %s" %\
                    (', '.join(invalid_fields), ', '.join(valid_fields), ', '.join([str(t) for t in kwargs.items()]))
            
    def _fk_one2one_insert(self, depth, max_depth, autoclobber):
        """
        Commit any related fk or one2one objects to the database
        Calls bulk_insert_commit on the related class
        """
        for name in self.related_queue.keys():
            if self.related_queue[name]:
                manager = self._find_bulk_manager(self.related_classes[name])
                self_ref = self.related_classes[name] == self.model
                r_queue, update_map = manager.bulk_insert_commit(now=self.now, depth=depth+1, 
                                                        max_depth=max_depth, autoclobber=autoclobber, _self_ref=self_ref)
                if r_queue:
                    pk_name = self.related_classes[name]._meta.pk.name

                    for arg_hash, keys in self.related_queue[name].items():
                        arg_hash = update_map.get(arg_hash, arg_hash)
                        for key in keys:
                            try:
                                self.queue[key][name] = r_queue[arg_hash][pk_name]
                            except KeyError, e:
                                if key in self.ref_cache.keys():
                                    print >> sys.stderr , "Warning: Too many recursive self references on a Foreign Key or OneToOne field class:%s field:%s - Value NOT Saved" % (self.model, name)
                                else:
                                    raise KeyError, e
                            
    def _many_to_one_insert(self, depth, max_depth, autoclobber):
        """
            Delayed bulk insert and commit of many to one relations
        """
        for name in self.m2one_queue.keys():
            manager = self._find_bulk_manager(self.m2one_classes[name])
            non_related_name = None
            for f in self.m2one_classes[name]._meta.fields:
                try:
                    if f.rel.related_name == name:
                        non_related_name = f.name
                        break
                except:
                    pass
            else:
                non_related_name = name + '_set'
                
            self_ref = self.m2one_classes[name] == self.model
            for args_list, key in self.m2one_queue[name]:
                key = self.update_map.get(key, key)
                pk = self.queue[key][self.model._meta.pk.name]
                for args in args_list:                      
                    args[non_related_name] = pk
                    manager.bulk_insert(now=self.now, _self_ref=self_ref, **args)
            manager.bulk_insert_commit(now=self.now, depth=depth+1, max_depth=max_depth, autoclobber=autoclobber, _self_ref=self_ref)
            
    def _many_to_many_insert(self, depth, max_depth, autoclobber):
        """
        Inserts all ManyToMany related objects and their relationships
        """
        for name in self.m2m_queue.keys():
            if self.m2m_queue[name]['bulk']:
                self_ref = self.m2m_classes[name] == self.model
                manager = self._find_bulk_manager(self.m2m_classes[name])
                r_queue, update_map = manager.bulk_insert_commit(now=self.now, depth=depth+1, max_depth=max_depth, autoclobber=autoclobber, _self_ref=self_ref)
                if r_queue:
                    for entry in self.m2m_queue[name]['list']:
                        for arg_hash in entry['bulk']:
                            entry['values'] += [r_queue[arg_hash][self.m2m_classes[name]._meta.pk.name]]
                else:
                    warning = "Max recursion depth, %s, exceeded. Some relationships between %s and %s may not be defined."
                    sys.stderr.write(warning % (max_depth, self.model.__name__, self.m2m_classes[name].__name__))
                
            if self.m2m_queue[name]['list']:
                table = self.m2m_fields[name].m2m_db_table()

                columns = [self.m2m_fields[name].m2m_column_name(), self.m2m_fields[name].m2m_reverse_name()]
                
                #Determine the direction of the ManyToMany Relationship
                #The special case of a self referential field requires further checking
                if self.m2m_fields[name].rel.to == self.model:
                    if self.m2m_classes[name] != self.model or not filter(lambda x: x.name==name, self.model._meta.many_to_many):
                        columns.reverse()
                
                #This value only matters for self referential relations
                symmetrical = False
                if self.m2m_classes[name] == self.model:
                    if getattr(self.m2m_fields[name].rel, 'symmetrical', False):
                        symmetrical = True
                    for key in self.ref_cache.keys():
                        self.queue[key] = self.ref_cache[key]
                        

                if len(self.m2m_queue[name]['list']) <= self.threshold or self.threshold < 0:
                    self.backend.insert_m2m(table, self.model._meta.pk.name, 
                                            columns, self.queue, self.m2m_queue[name], 
                                            self.update_map, autoclobber, symmetrical)
                else:
                    self.backend.write_m2m_temp_file(self.model._meta.pk.name, self.queue, self.m2m_queue[name], self.update_map, symmetrical)
    
                    self.backend.insert_from_file(table, columns, autoclobber)
            
            
    def _recover_pks