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Diffstat (limited to 'django/db/models/query.py')
| -rw-r--r-- | django/db/models/query.py | 888 |
1 files changed, 888 insertions, 0 deletions
diff --git a/django/db/models/query.py b/django/db/models/query.py new file mode 100644 index 0000000000..365ead2a3a --- /dev/null +++ b/django/db/models/query.py @@ -0,0 +1,888 @@ +from django.db import backend, connection, transaction +from django.db.models.fields import DateField, FieldDoesNotExist +from django.db.models import signals +from django.dispatch import dispatcher +from django.utils.datastructures import SortedDict + +import operator + +# For Python 2.3 +if not hasattr(__builtins__, 'set'): + from sets import Set as set + +LOOKUP_SEPARATOR = '__' + +# Size of each "chunk" for get_iterator calls. +# Larger values are slightly faster at the expense of more storage space. +GET_ITERATOR_CHUNK_SIZE = 100 + +#################### +# HELPER FUNCTIONS # +#################### + +# Django currently supports two forms of ordering. +# Form 1 (deprecated) example: +# order_by=(('pub_date', 'DESC'), ('headline', 'ASC'), (None, 'RANDOM')) +# Form 2 (new-style) example: +# order_by=('-pub_date', 'headline', '?') +# Form 1 is deprecated and will no longer be supported for Django's first +# official release. The following code converts from Form 1 to Form 2. + +LEGACY_ORDERING_MAPPING = {'ASC': '_', 'DESC': '-_', 'RANDOM': '?'} + +def handle_legacy_orderlist(order_list): + if not order_list or isinstance(order_list[0], basestring): + return order_list + else: + import warnings + new_order_list = [LEGACY_ORDERING_MAPPING[j.upper()].replace('_', str(i)) for i, j in order_list] + warnings.warn("%r ordering syntax is deprecated. Use %r instead." % (order_list, new_order_list), DeprecationWarning) + return new_order_list + +def orderfield2column(f, opts): + try: + return opts.get_field(f, False).column + except FieldDoesNotExist: + return f + +def orderlist2sql(order_list, opts, prefix=''): + if prefix.endswith('.'): + prefix = backend.quote_name(prefix[:-1]) + '.' + output = [] + for f in handle_legacy_orderlist(order_list): + if f.startswith('-'): + output.append('%s%s DESC' % (prefix, backend.quote_name(orderfield2column(f[1:], opts)))) + elif f == '?': + output.append(backend.get_random_function_sql()) + else: + output.append('%s%s ASC' % (prefix, backend.quote_name(orderfield2column(f, opts)))) + return ', '.join(output) + +def quote_only_if_word(word): + if ' ' in word: + return word + else: + return backend.quote_name(word) + +class QuerySet(object): + "Represents a lazy database lookup for a set of objects" + def __init__(self, model=None): + self.model = model + self._filters = Q() + self._order_by = None # Ordering, e.g. ('date', '-name'). If None, use model's ordering. + self._select_related = False # Whether to fill cache for related objects. + self._distinct = False # Whether the query should use SELECT DISTINCT. + self._select = {} # Dictionary of attname -> SQL. + self._where = [] # List of extra WHERE clauses to use. + self._params = [] # List of params to use for extra WHERE clauses. + self._tables = [] # List of extra tables to use. + self._offset = None # OFFSET clause + self._limit = None # LIMIT clause + self._result_cache = None + + ######################## + # PYTHON MAGIC METHODS # + ######################## + + def __repr__(self): + return repr(self._get_data()) + + def __len__(self): + return len(self._get_data()) + + def __iter__(self): + return iter(self._get_data()) + + def __getitem__(self, k): + "Retrieve an item or slice from the set of results." + if self._result_cache is None: + if isinstance(k, slice): + # Offset: + if self._offset is None: + offset = k.start + elif k.start is None: + offset = self._offset + else: + offset = self._offset + k.start + # Now adjust offset to the bounds of any existing limit: + if self._limit is not None and k.start is not None: + limit = self._limit - k.start + else: + limit = self._limit + + # Limit: + if k.stop is not None and k.start is not None: + if limit is None: + limit = k.stop - k.start + else: + limit = min((k.stop - k.start), limit) + else: + if limit is None: + limit = k.stop + else: + if k.stop is not None: + limit = min(k.stop, limit) + + if k.step is None: + return self._clone(_offset=offset, _limit=limit) + else: + return list(self._clone(_offset=offset, _limit=limit))[::k.step] + else: + return self._clone(_offset=k, _limit=1).get() + else: + return self._result_cache[k] + + def __and__(self, other): + combined = self._combine(other) + combined._filters = self._filters & other._filters + return combined + + def __or__(self, other): + combined = self._combine(other) + combined._filters = self._filters | other._filters + return combined + + #################################### + # METHODS THAT DO DATABASE QUERIES # + #################################### + + def iterator(self): + "Performs the SELECT database lookup of this QuerySet." + # self._select is a dictionary, and dictionaries' key order is + # undefined, so we convert it to a list of tuples. + extra_select = self._select.items() + + cursor = connection.cursor() + select, sql, params = self._get_sql_clause() + cursor.execute("SELECT " + (self._distinct and "DISTINCT " or "") + ",".join(select) + sql, params) + fill_cache = self._select_related + index_end = len(self.model._meta.fields) + while 1: + rows = cursor.fetchmany(GET_ITERATOR_CHUNK_SIZE) + if not rows: + raise StopIteration + for row in rows: + if fill_cache: + obj, index_end = get_cached_row(self.model, row, 0) + else: + obj = self.model(*row[:index_end]) + for i, k in enumerate(extra_select): + setattr(obj, k[0], row[index_end+i]) + yield obj + + def count(self): + "Performs a SELECT COUNT() and returns the number of records as an integer." + counter = self._clone() + counter._order_by = () + counter._offset = None + counter._limit = None + counter._select_related = False + select, sql, params = counter._get_sql_clause() + cursor = connection.cursor() + cursor.execute("SELECT COUNT(*)" + sql, params) + return cursor.fetchone()[0] + + def get(self, *args, **kwargs): + "Performs the SELECT and returns a single object matching the given keyword arguments." + clone = self.filter(*args, **kwargs) + if not clone._order_by: + clone._order_by = () + obj_list = list(clone) + if len(obj_list) < 1: + raise self.model.DoesNotExist, "%s does not exist for %s" % (self.model._meta.object_name, kwargs) + assert len(obj_list) == 1, "get() returned more than one %s -- it returned %s! Lookup parameters were %s" % (self.model._meta.object_name, len(obj_list), kwargs) + return obj_list[0] + + def latest(self, field_name=None): + """ + Returns the latest object, according to the model's 'get_latest_by' + option or optional given field_name. + """ + latest_by = field_name or self.model._meta.get_latest_by + assert bool(latest_by), "latest() requires either a field_name parameter or 'get_latest_by' in the model" + assert self._limit is None and self._offset is None, \ + "Cannot change a query once a slice has been taken." + return self._clone(_limit=1, _order_by=('-'+latest_by,)).get() + + def in_bulk(self, id_list): + """ + Returns a dictionary mapping each of the given IDs to the object with + that ID. + """ + assert self._limit is None and self._offset is None, \ + "Cannot use 'limit' or 'offset' with in_bulk" + assert isinstance(id_list, (tuple, list)), "in_bulk() must be provided with a list of IDs." + id_list = list(id_list) + if id_list == []: + return {} + qs = self._clone() + qs._where.append("%s.%s IN (%s)" % (backend.quote_name(self.model._meta.db_table), backend.quote_name(self.model._meta.pk.column), ",".join(['%s'] * len(id_list)))) + qs._params.extend(id_list) + return dict([(obj._get_pk_val(), obj) for obj in qs.iterator()]) + + def delete(self): + """ + Deletes the records in the current QuerySet. + """ + assert self._limit is None and self._offset is None, \ + "Cannot use 'limit' or 'offset' with delete." + + del_query = self._clone() + + # disable non-supported fields + del_query._select_related = False + del_query._order_by = [] + + # Delete objects in chunks to prevent an the list of + # related objects from becoming too long + more_objects = True + while more_objects: + # 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() + more_objects = False + for object in del_query[0:GET_ITERATOR_CHUNK_SIZE]: + more_objects = True + object._collect_sub_objects(seen_objs) + + # If one or more objects were found, delete them. + # Otherwise, stop looping. + if more_objects: + delete_objects(seen_objs) + + # Clear the result cache, in case this QuerySet gets reused. + self._result_cache = None + delete.alters_data = True + + ################################################## + # PUBLIC METHODS THAT RETURN A QUERYSET SUBCLASS # + ################################################## + + def values(self, *fields): + return self._clone(klass=ValuesQuerySet, _fields=fields) + + def dates(self, field_name, kind, order='ASC'): + """ + Returns a list of datetime objects representing all available dates + for the given field_name, scoped to 'kind'. + """ + assert kind in ("month", "year", "day"), "'kind' must be one of 'year', 'month' or 'day'." + assert order in ('ASC', 'DESC'), "'order' must be either 'ASC' or 'DESC'." + # Let the FieldDoesNotExist exception propagate. + field = self.model._meta.get_field(field_name, many_to_many=False) + assert isinstance(field, DateField), "%r isn't a DateField." % field_name + return self._clone(klass=DateQuerySet, _field=field, _kind=kind, _order=order) + + ################################################################## + # PUBLIC METHODS THAT ALTER ATTRIBUTES AND RETURN A NEW QUERYSET # + ################################################################## + + def filter(self, *args, **kwargs): + "Returns a new QuerySet instance with the args ANDed to the existing set." + return self._filter_or_exclude(Q, *args, **kwargs) + + def exclude(self, *args, **kwargs): + "Returns a new QuerySet instance with NOT (args) ANDed to the existing set." + return self._filter_or_exclude(QNot, *args, **kwargs) + + def _filter_or_exclude(self, qtype, *args, **kwargs): + if len(args) > 0 or len(kwargs) > 0: + assert self._limit is None and self._offset is None, \ + "Cannot filter a query once a slice has been taken." + + clone = self._clone() + if len(kwargs) > 0: + clone._filters = clone._filters & qtype(**kwargs) + if len(args) > 0: + clone._filters = clone._filters & reduce(operator.and_, args) + return clone + + def select_related(self, true_or_false=True): + "Returns a new QuerySet instance with '_select_related' modified." + return self._clone(_select_related=true_or_false) + + def order_by(self, *field_names): + "Returns a new QuerySet instance with the ordering changed." + assert self._limit is None and self._offset is None, \ + "Cannot reorder a query once a slice has been taken." + return self._clone(_order_by=field_names) + + def distinct(self, true_or_false=True): + "Returns a new QuerySet instance with '_distinct' modified." + return self._clone(_distinct=true_or_false) + + def extra(self, select=None, where=None, params=None, tables=None): + assert self._limit is None and self._offset is None, \ + "Cannot change a query once a slice has been taken" + clone = self._clone() + if select: clone._select.update(select) + if where: clone._where.extend(where) + if params: clone._params.extend(params) + if tables: clone._tables.extend(tables) + return clone + + ################### + # PRIVATE METHODS # + ################### + + def _clone(self, klass=None, **kwargs): + if klass is None: + klass = self.__class__ + c = klass() + c.model = self.model + c._filters = self._filters + c._order_by = self._order_by + c._select_related = self._select_related + c._distinct = self._distinct + c._select = self._select.copy() + c._where = self._where[:] + c._params = self._params[:] + c._tables = self._tables[:] + c._offset = self._offset + c._limit = self._limit + c.__dict__.update(kwargs) + return c + + def _combine(self, other): + assert self._limit is None and self._offset is None \ + and other._limit is None and other._offset is None, \ + "Cannot combine queries once a slice has been taken." + assert self._distinct == other._distinct, \ + "Cannot combine a unique query with a non-unique query" + # use 'other's order by + # (so that A.filter(args1) & A.filter(args2) does the same as + # A.filter(args1).filter(args2) + combined = other._clone() + # If 'self' is ordered and 'other' isn't, propagate 'self's ordering + if (self._order_by is not None and len(self._order_by) > 0) and \ + (combined._order_by is None or len(combined._order_by) == 0): + combined._order_by = self._order_by + return combined + + def _get_data(self): + if self._result_cache is None: + self._result_cache = list(self.iterator()) + return self._result_cache + + def _get_sql_clause(self): + opts = self.model._meta + + # Construct the fundamental parts of the query: SELECT X FROM Y WHERE Z. + select = ["%s.%s" % (backend.quote_name(opts.db_table), backend.quote_name(f.column)) for f in opts.fields] + tables = [quote_only_if_word(t) for t in self._tables] + joins = SortedDict() + where = self._where[:] + params = self._params[:] + + # Convert self._filters into SQL. + tables2, joins2, where2, params2 = self._filters.get_sql(opts) + tables.extend(tables2) + joins.update(joins2) + where.extend(where2) + params.extend(params2) + + # Add additional tables and WHERE clauses based on select_related. + if self._select_related: + fill_table_cache(opts, select, tables, where, opts.db_table, [opts.db_table]) + + # Add any additional SELECTs. + if self._select: + select.extend(['(%s) AS %s' % (quote_only_if_word(s[1]), backend.quote_name(s[0])) for s in self._select.items()]) + + # Start composing the body of the SQL statement. + sql = [" FROM", backend.quote_name(opts.db_table)] + + # Compose the join dictionary into SQL describing the joins. + if joins: + sql.append(" ".join(["%s %s AS %s ON %s" % (join_type, table, alias, condition) + for (alias, (table, join_type, condition)) in joins.items()])) + + # Compose the tables clause into SQL. + if tables: + sql.append(", " + ", ".join(tables)) + + # Compose the where clause into SQL. + if where: + sql.append(where and "WHERE " + " AND ".join(where)) + + # ORDER BY clause + order_by = [] + if self._order_by is not None: + ordering_to_use = self._order_by + else: + ordering_to_use = opts.ordering + for f in handle_legacy_orderlist(ordering_to_use): + if f == '?': # Special case. + order_by.append(backend.get_random_function_sql()) + else: + if f.startswith('-'): + col_name = f[1:] + order = "DESC" + else: + col_name = f + order = "ASC" + if "." in col_name: + table_prefix, col_name = col_name.split('.', 1) + table_prefix = backend.quote_name(table_prefix) + '.' + else: + # Use the database table as a column prefix if it wasn't given, + # and if the requested column isn't a custom SELECT. + if "." not in col_name and col_name not in (self._select or ()): + table_prefix = backend.quote_name(opts.db_table) + '.' + else: + table_prefix = '' + order_by.append('%s%s %s' % (table_prefix, backend.quote_name(orderfield2column(col_name, opts)), order)) + if order_by: + sql.append("ORDER BY " + ", ".join(order_by)) + + # LIMIT and OFFSET clauses + if self._limit is not None: + sql.append("%s " % backend.get_limit_offset_sql(self._limit, self._offset)) + else: + assert self._offset is None, "'offset' is not allowed without 'limit'" + + return select, " ".join(sql), params + +class ValuesQuerySet(QuerySet): + def iterator(self): + # select_related and select aren't supported in values(). + self._select_related = False + self._select = {} + + # self._fields is a list of field names to fetch. + if self._fields: + columns = [self.model._meta.get_field(f, many_to_many=False).column for f in self._fields] + field_names = self._fields + else: # Default to all fields. + columns = [f.column for f in self.model._meta.fields] + field_names = [f.attname for f in self.model._meta.fields] + + cursor = connection.cursor() + select, sql, params = self._get_sql_clause() + select = ['%s.%s' % (backend.quote_name(self.model._meta.db_table), backend.quote_name(c)) for c in columns] + cursor.execute("SELECT " + (self._distinct and "DISTINCT " or "") + ",".join(select) + sql, params) + while 1: + rows = cursor.fetchmany(GET_ITERATOR_CHUNK_SIZE) + if not rows: + raise StopIteration + for row in rows: + yield dict(zip(field_names, row)) + + def _clone(self, klass=None, **kwargs): + c = super(ValuesQuerySet, self)._clone(klass, **kwargs) + c._fields = self._fields[:] + return c + +class DateQuerySet(QuerySet): + def iterator(self): + from django.db.backends.util import typecast_timestamp + self._order_by = () # Clear this because it'll mess things up otherwise. + if self._field.null: + date_query._where.append('%s.%s IS NOT NULL' % \ + (backend.quote_name(self.model._meta.db_table), backend.quote_name(self._field.column))) + select, sql, params = self._get_sql_clause() + sql = 'SELECT %s %s GROUP BY 1 ORDER BY 1 %s' % \ + (backend.get_date_trunc_sql(self._kind, '%s.%s' % (backend.quote_name(self.model._meta.db_table), + backend.quote_name(self._field.column))), sql, self._order) + cursor = connection.cursor() + cursor.execute(sql, params) + # We have to manually run typecast_timestamp(str()) on the results, because + # MySQL doesn't automatically cast the result of date functions as datetime + # objects -- MySQL returns the values as strings, instead. + return [typecast_timestamp(str(row[0])) for row in cursor.fetchall()] + + def _clone(self, klass=None, **kwargs): + c = super(DateQuerySet, self)._clone(klass, **kwargs) + c._field = self._field + c._kind = self._kind + c._order = self._order + return c + +class QOperator: + "Base class for QAnd and QOr" + def __init__(self, *args): + self.args = args + + def get_sql(self, opts): + tables, joins, where, params = [], SortedDict(), [], [] + for val in self.args: + tables2, joins2, where2, params2 = val.get_sql(opts) + tables.extend(tables2) + joins.update(joins2) + where.extend(where2) + params.extend(params2) + if where: + return tables, joins, ['(%s)' % self.operator.join(where)], params + return tables, joins, [], params + +class QAnd(QOperator): + "Encapsulates a combined query that uses 'AND'." + operator = ' AND ' + def __or__(self, other): + return QOr(self, other) + + def __and__(self, other): + if isinstance(other, QAnd): + return QAnd(*(self.args+other.args)) + elif isinstance(other, (Q, QOr)): + return QAnd(*(self.args+(other,))) + else: + raise TypeError, other + +class QOr(QOperator): + "Encapsulates a combined query that uses 'OR'." + operator = ' OR ' + def __and__(self, other): + return QAnd(self, other) + + def __or__(self, other): + if isinstance(other, QOr): + return QOr(*(self.args+other.args)) + elif isinstance(other, (Q, QAnd)): + return QOr(*(self.args+(other,))) + else: + raise TypeError, other + +class Q(object): + "Encapsulates queries as objects that can be combined logically." + def __init__(self, **kwargs): + self.kwargs = kwargs + + def __and__(self, other): + return QAnd(self, other) + + def __or__(self, other): + return QOr(self, other) + + def get_sql(self, opts): + return parse_lookup(self.kwargs.items(), opts) + +class QNot(Q): + "Encapsulates NOT (...) queries as objects" + + def get_sql(self, opts): + tables, joins, where, params = super(QNot, self).get_sql(opts) + where2 = ['(NOT (%s))' % " AND ".join(where)] + return tables, joins, where2, params + +def get_where_clause(lookup_type, table_prefix, field_name, value): + if table_prefix.endswith('.'): + table_prefix = backend.quote_name(table_prefix[:-1])+'.' + field_name = backend.quote_name(field_name) + try: + return '%s%s %s' % (table_prefix, field_name, (backend.OPERATOR_MAPPING[lookup_type] % '%s')) + except KeyError: + pass + if lookup_type == 'in': + return '%s%s IN (%s)' % (table_prefix, field_name, ','.join(['%s' for v in value])) + elif lookup_type == 'range': + return '%s%s BETWEEN %%s AND %%s' % (table_prefix, field_name) + elif lookup_type in ('year', 'month', 'day'): + return "%s = %%s" % backend.get_date_extract_sql(lookup_type, table_prefix + field_name) + elif lookup_type == 'isnull': + return "%s%s IS %sNULL" % (table_prefix, field_name, (not value and 'NOT ' or '')) + raise TypeError, "Got invalid lookup_type: %s" % repr(lookup_type) + +def get_cached_row(klass, row, index_start): + "Helper function that recursively returns an object with cache filled" + index_end = index_start + len(klass._meta.fields) + obj = klass(*row[index_start:index_end]) + for f in klass._meta.fields: + if f.rel and not f.null: + rel_obj, index_end = get_cached_row(f.rel.to, row, index_end) + setattr(obj, f.get_cache_name(), rel_obj) + return obj, index_end + +def fill_table_cache(opts, select, tables, where, old_prefix, cache_tables_seen): + """ + Helper function that recursively populates the select, tables and where (in + place) for fill-cache queries. + """ + for f in opts.fields: + if f.rel and not f.null: + db_table = f.rel.to._meta.db_table + if db_table not in cache_tables_seen: + tables.append(backend.quote_name(db_table)) + else: # The table was already seen, so give it a table alias. + new_prefix = '%s%s' % (db_table, len(cache_tables_seen)) + tables.append('%s %s' % (backend.quote_name(db_table), backend.quote_name(new_prefix))) + db_table = new_prefix + cache_tables_seen.append(db_table) + where.append('%s.%s = %s.%s' % \ + (backend.quote_name(old_prefix), backend.quote_name(f.column), + backend.quote_name(db_table), backend.quote_name(f.rel.get_related_field().column))) + select.extend(['%s.%s' % (backend.quote_name(db_table), backend.quote_name(f2.column)) for f2 in f.rel.to._meta.fields]) + fill_table_cache(f.rel.to._meta, select, tables, where, db_table, cache_tables_seen) + +def parse_lookup(kwarg_items, opts): + # Helper function that handles converting API kwargs + # (e.g. "name__exact": "tom") to SQL. + + # 'joins' is a sorted dictionary describing the tables that must be joined + # to complete the query. The dictionary is sorted because creation order + # is significant; it is a dictionary to ensure uniqueness of alias names. + # + # Each key-value pair follows the form + # alias: (table, join_type, condition) + # where + # alias is the AS alias for the joined table + # table is the actual table name to be joined + # join_type is the type of join (INNER JOIN, LEFT OUTER JOIN, etc) + # condition is the where-like statement over which narrows the join. + # alias will be derived from the lookup list name. + # + # At present, this method only every returns INNER JOINs; the option is + # there for others to implement custom Q()s, etc that return other join + # types. + tables, joins, where, params = [], SortedDict(), [], [] + + for kwarg, value in kwarg_items: + if value is not None: + path = kwarg.split(LOOKUP_SEPARATOR) + # Extract the last elements of the kwarg. + # The very-last is the clause (equals, like, etc). + # The second-last is the table column on which the clause is + # to be performed. + # The exceptions to this are: + # 1) "pk", which is an implicit id__exact; + # if we find "pk", make the clause "exact', and insert + # a dummy name of None, which we will replace when + # we know which table column to grab as the primary key. + # 2) If there is only one part, assume it to be an __exact + clause = path.pop() + if clause == 'pk': + clause = 'exact' + path.append(None) + elif len(path) == 0: + path.append(clause) + clause = 'exact' + + if len(path) < 1: + raise TypeError, "Cannot parse keyword query %r" % kwarg + + tables2, joins2, where2, params2 = lookup_inner(path, clause, value, opts, opts.db_table, None) + tables.extend(tables2) + joins.update(joins2) + where.extend(where2) + params.extend(params2) + return tables, joins, where, params + +class FieldFound(Exception): + "Exception used to short circuit field-finding operations." + pass + +def find_field(name, field_list, related_query): + """ + Finds a field with a specific name in a list of field instances. + Returns None if there are no matches, or several matches. + """ + if related_query: + matches = [f for f in field_list if f.field.related_query_name() == name] + else: + matches = [f for f in field_list if f.name == name] + if len(matches) != 1: + return None + return matches[0] + +def lookup_inner(path, clause, value, opts, table, column): + tables, joins, where, params = [], SortedDict(), [], [] + current_opts = opts + current_table = table + current_column = column + intermediate_table = None + join_required = False + + name = path.pop(0) + # Has the primary key been requested? If so, expand it out + # to be the name of the current class' primary key + if name is None: + name = current_opts.pk.name + + # Try to find the name in the fields associated with the current class + try: + # Does the name belong to a defined many-to-many field? + field = find_field(name, current_opts.many_to_many, False) + if field: + new_table = current_table + LOOKUP_SEPARATOR + name + new_opts = field.rel.to._meta + new_column = new_opts.pk.column + + # Need to create an intermediate table join over the m2m table + # This process hijacks current_table/column to point to the + # intermediate table. + current_table = "m2m_" + new_table + intermediate_table = field.m2m_db_table() + join_column = field.m2m_reverse_name() + intermediate_column = field.m2m_column_name() + + raise FieldFound + + # Does the name belong to a reverse defined many-to-many field? + field = find_field(name, current_opts.get_all_related_many_to_many_objects(), True) + if field: + new_table = current_table + LOOKUP_SEPARATOR + name + new_opts = field.opts + new_column = new_opts.pk.column + + # Need to create an intermediate table join over the m2m table. + # This process hijacks current_table/column to point to the + # intermediate table. + current_table = "m2m_" + new_table + intermediate_table = field.field.m2m_db_table() + join_column = field.field.m2m_column_name() + intermediate_column = field.field.m2m_reverse_name() + + raise FieldFound + + # Does the name belong to a one-to-many field? + field = find_field(name, current_opts.get_all_related_objects(), True) + if field: + new_table = table + LOOKUP_SEPARATOR + name + new_opts = field.opts + new_column = field.field.column + join_column = opts.pk.column + + # 1-N fields MUST be joined, regardless of any other conditions. + join_required = True + + raise FieldFound + + # Does the name belong to a one-to-one, many-to-one, or regular field? + field = find_field(name, current_opts.fields, False) + if field: + if field.rel: # One-to-One/Many-to-one field + new_table = current_table + LOOKUP_SEPARATOR + name + new_opts = field.rel.to._meta + new_column = new_opts.pk.column + join_column = field.column + + raise FieldFound + + except FieldFound: # Match found, loop has been shortcut. + pass + except: # Any other exception; rethrow + raise + else: # No match found. + raise TypeError, "Cannot resolve keyword '%s' into field" % name + + # Check to see if an intermediate join is required between current_table + # and new_table. + if intermediate_table: + joins[backend.quote_name(current_table)] = ( + backend.quote_name(intermediate_table), + "LEFT OUTER JOIN", + "%s.%s = %s.%s" % \ + (backend.quote_name(table), + backend.quote_name(current_opts.pk.column), + backend.quote_name(current_table), + backend.quote_name(intermediate_column)) + ) + + if path: + if len(path) == 1 and path[0] in (new_opts.pk.name, None) \ + and clause in ('exact', 'isnull') and not join_required: + # If the last name query is for a key, and the search is for + # isnull/exact, then the current (for N-1) or intermediate + # (for N-N) table can be used for the search - no need to join an + # extra table just to check the primary key. + new_table = current_table + else: + # There are 1 or more name queries pending, and we have ruled out + # any shortcuts; therefore, a join is required. + joins[backend.quote_name(new_table)] = ( + backend.quote_name(new_opts.db_table), + "INNER JOIN", + "%s.%s = %s.%s" % + (backend.quote_name(current_table), + backend.quote_name(join_column), + backend.quote_name(new_table), + backend.quote_name(new_column)) + ) + # If we have made the join, we don't need to tell subsequent + # recursive calls about the column name we joined on. + join_column = None + + # There are name queries remaining. Recurse deeper. + tables2, joins2, where2, params2 = lookup_inner(path, clause, value, new_opts, new_table, join_column) + + tables.extend(tables2) + joins.update(joins2) + where.extend(where2) + params.extend(params2) + else: + # Evaluate clause on current table. + if name in (current_opts.pk.name, None) and clause in ('exact', 'isnull') and current_column: + # If this is an exact/isnull key search, and the last pass + # found/introduced a current/intermediate table that we can use to + # optimize the query, then use that column name. + column = current_column + else: + column = field.column + + where.append(get_where_clause(clause, current_table + '.', column, value)) + params.extend(field.get_db_prep_lookup(clause, value)) + + return tables, joins, where, params + +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() + + cursor = connection.cursor() + + for cls in ordered_classes: + seen_objs[cls] = seen_objs[cls].items() + seen_objs[cls].sort() + + # Pre notify all instances to be deleted + for pk_val, instance in seen_objs[cls]: + dispatcher.send(signal=signals.pre_delete, sender=cls, instance=instance) + + pk_list = [pk for pk,instance in seen_objs[cls]] + for related in cls._meta.get_all_related_many_to_many_objects(): + for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE): + cursor.execute("DELETE FROM %s WHERE %s IN (%s)" % \ + (backend.quote_name(related.field.m2m_db_table()), + backend.quote_name(related.field.m2m_reverse_name()), + ','.join(['%s' for pk in pk_list[offset:offset+GET_ITERATOR_CHUNK_SIZE]])), + pk_list[offset:offset+GET_ITERATOR_CHUNK_SIZE]) + for f in cls._meta.many_to_many: + for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE): + cursor.execute("DELETE FROM %s WHERE %s IN (%s)" % \ + (backend.quote_name(f.m2m_db_table()), + backend.quote_name(f.m2m_column_name()), + ','.join(['%s' for pk in pk_list[offset:offset+GET_ITERATOR_CHUNK_SIZE]])), + pk_list[offset:offset+GET_ITERATOR_CHUNK_SIZE]) + for field in cls._meta.fields: + if field.rel and field.null and field.rel.to in seen_objs: + for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE): + cursor.execute("UPDATE %s SET %s=NULL WHERE %s IN (%s)" % \ + (backend.quote_name(cls._meta.db_table), + backend.quote_name(field.column), + backend.quote_name(cls._meta.pk.column), + ','.join(['%s' for pk in pk_list[offset:offset+GET_ITERATOR_CHUNK_SIZE]])), + pk_list[offset:offset+GET_ITERATOR_CHUNK_SIZE]) + + # Now delete the actual data + for cls in ordered_classes: + seen_objs[cls].reverse() + pk_list = [pk for pk,instance in seen_objs[cls]] + for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE): + cursor.execute("DELETE FROM %s WHERE %s IN (%s)" % \ + (backend.quote_name(cls._meta.db_table), + backend.quote_name(cls._meta.pk.column), + ','.join(['%s' for pk in pk_list[offset:offset+GET_ITERATOR_CHUNK_SIZE]])), + pk_list[offset:offset+GET_ITERATOR_CHUNK_SIZE]) + + # 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 field in cls._meta.fields: + if field.rel and field.null and field.rel.to in seen_objs: + setattr(instance, field.attname, None) + + setattr(instance, cls._meta.pk.attname, None) + dispatcher.send(signal=signals.post_delete, sender=cls, instance=instance) + + transaction.commit_unless_managed() |