| """ |
| Create SQL statements for QuerySets. |
| |
| The code in here encapsulates all of the SQL construction so that QuerySets |
| themselves do not have to (and could be backed by things other than SQL |
| databases). The abstraction barrier only works one way: this module has to know |
| all about the internals of models in order to get the information it needs. |
| """ |
| |
| from django.utils.copycompat import deepcopy |
| from django.utils.tree import Node |
| from django.utils.datastructures import SortedDict |
| from django.utils.encoding import force_unicode |
| from django.db import connections, DEFAULT_DB_ALIAS |
| from django.db.models import signals |
| from django.db.models.fields import FieldDoesNotExist |
| from django.db.models.query_utils import select_related_descend, InvalidQuery |
| from django.db.models.sql import aggregates as base_aggregates_module |
| from django.db.models.sql.constants import * |
| from django.db.models.sql.datastructures import EmptyResultSet, Empty, MultiJoin |
| from django.db.models.sql.expressions import SQLEvaluator |
| from django.db.models.sql.where import (WhereNode, Constraint, EverythingNode, |
| ExtraWhere, AND, OR) |
| from django.core.exceptions import FieldError |
| |
| __all__ = ['Query', 'RawQuery'] |
| |
| class RawQuery(object): |
| """ |
| A single raw SQL query |
| """ |
| |
| def __init__(self, sql, using, params=None): |
| self.validate_sql(sql) |
| self.params = params or () |
| self.sql = sql |
| self.using = using |
| self.cursor = None |
| |
| # Mirror some properties of a normal query so that |
| # the compiler can be used to process results. |
| self.low_mark, self.high_mark = 0, None # Used for offset/limit |
| self.extra_select = {} |
| self.aggregate_select = {} |
| |
| def clone(self, using): |
| return RawQuery(self.sql, using, params=self.params) |
| |
| def convert_values(self, value, field, connection): |
| """Convert the database-returned value into a type that is consistent |
| across database backends. |
| |
| By default, this defers to the underlying backend operations, but |
| it can be overridden by Query classes for specific backends. |
| """ |
| return connection.ops.convert_values(value, field) |
| |
| def get_columns(self): |
| if self.cursor is None: |
| self._execute_query() |
| converter = connections[self.using].introspection.table_name_converter |
| return [converter(column_meta[0]) |
| for column_meta in self.cursor.description] |
| |
| def validate_sql(self, sql): |
| if not sql.lower().strip().startswith('select'): |
| raise InvalidQuery('Raw queries are limited to SELECT queries. Use ' |
| 'connection.cursor directly for other types of queries.') |
| |
| def __iter__(self): |
| # Always execute a new query for a new iterator. |
| # This could be optimized with a cache at the expense of RAM. |
| self._execute_query() |
| if not connections[self.using].features.can_use_chunked_reads: |
| # If the database can't use chunked reads we need to make sure we |
| # evaluate the entire query up front. |
| result = list(self.cursor) |
| else: |
| result = self.cursor |
| return iter(result) |
| |
| def __repr__(self): |
| return "<RawQuery: %r>" % (self.sql % self.params) |
| |
| def _execute_query(self): |
| self.cursor = connections[self.using].cursor() |
| self.cursor.execute(self.sql, self.params) |
| |
| |
| class Query(object): |
| """ |
| A single SQL query. |
| """ |
| # SQL join types. These are part of the class because their string forms |
| # vary from database to database and can be customised by a subclass. |
| INNER = 'INNER JOIN' |
| LOUTER = 'LEFT OUTER JOIN' |
| |
| alias_prefix = 'T' |
| query_terms = QUERY_TERMS |
| aggregates_module = base_aggregates_module |
| |
| compiler = 'SQLCompiler' |
| |
| def __init__(self, model, where=WhereNode): |
| self.model = model |
| self.alias_refcount = {} |
| self.alias_map = {} # Maps alias to join information |
| self.table_map = {} # Maps table names to list of aliases. |
| self.join_map = {} |
| self.rev_join_map = {} # Reverse of join_map. |
| self.quote_cache = {} |
| self.default_cols = True |
| self.default_ordering = True |
| self.standard_ordering = True |
| self.ordering_aliases = [] |
| self.select_fields = [] |
| self.related_select_fields = [] |
| self.dupe_avoidance = {} |
| self.used_aliases = set() |
| self.filter_is_sticky = False |
| self.included_inherited_models = {} |
| |
| # SQL-related attributes |
| self.select = [] |
| self.tables = [] # Aliases in the order they are created. |
| self.where = where() |
| self.where_class = where |
| self.group_by = None |
| self.having = where() |
| self.order_by = [] |
| self.low_mark, self.high_mark = 0, None # Used for offset/limit |
| self.distinct = False |
| self.select_related = False |
| self.related_select_cols = [] |
| |
| # SQL aggregate-related attributes |
| self.aggregates = SortedDict() # Maps alias -> SQL aggregate function |
| self.aggregate_select_mask = None |
| self._aggregate_select_cache = None |
| |
| # Arbitrary maximum limit for select_related. Prevents infinite |
| # recursion. Can be changed by the depth parameter to select_related(). |
| self.max_depth = 5 |
| |
| # These are for extensions. The contents are more or less appended |
| # verbatim to the appropriate clause. |
| self.extra = SortedDict() # Maps col_alias -> (col_sql, params). |
| self.extra_select_mask = None |
| self._extra_select_cache = None |
| |
| self.extra_tables = () |
| self.extra_order_by = () |
| |
| # A tuple that is a set of model field names and either True, if these |
| # are the fields to defer, or False if these are the only fields to |
| # load. |
| self.deferred_loading = (set(), True) |
| |
| def __str__(self): |
| """ |
| Returns the query as a string of SQL with the parameter values |
| substituted in. |
| |
| Parameter values won't necessarily be quoted correctly, since that is |
| done by the database interface at execution time. |
| """ |
| sql, params = self.get_compiler(DEFAULT_DB_ALIAS).as_sql() |
| return sql % params |
| |
| def __deepcopy__(self, memo): |
| result = self.clone(memo=memo) |
| memo[id(self)] = result |
| return result |
| |
| def __getstate__(self): |
| """ |
| Pickling support. |
| """ |
| obj_dict = self.__dict__.copy() |
| obj_dict['related_select_fields'] = [] |
| obj_dict['related_select_cols'] = [] |
| |
| # Fields can't be pickled, so if a field list has been |
| # specified, we pickle the list of field names instead. |
| # None is also a possible value; that can pass as-is |
| obj_dict['select_fields'] = [ |
| f is not None and f.name or None |
| for f in obj_dict['select_fields'] |
| ] |
| return obj_dict |
| |
| def __setstate__(self, obj_dict): |
| """ |
| Unpickling support. |
| """ |
| # Rebuild list of field instances |
| opts = obj_dict['model']._meta |
| obj_dict['select_fields'] = [ |
| name is not None and opts.get_field(name) or None |
| for name in obj_dict['select_fields'] |
| ] |
| |
| self.__dict__.update(obj_dict) |
| |
| def prepare(self): |
| return self |
| |
| def get_compiler(self, using=None, connection=None): |
| if using is None and connection is None: |
| raise ValueError("Need either using or connection") |
| if using: |
| connection = connections[using] |
| |
| # Check that the compiler will be able to execute the query |
| for alias, aggregate in self.aggregate_select.items(): |
| connection.ops.check_aggregate_support(aggregate) |
| |
| return connection.ops.compiler(self.compiler)(self, connection, using) |
| |
| def get_meta(self): |
| """ |
| Returns the Options instance (the model._meta) from which to start |
| processing. Normally, this is self.model._meta, but it can be changed |
| by subclasses. |
| """ |
| return self.model._meta |
| |
| def clone(self, klass=None, memo=None, **kwargs): |
| """ |
| Creates a copy of the current instance. The 'kwargs' parameter can be |
| used by clients to update attributes after copying has taken place. |
| """ |
| obj = Empty() |
| obj.__class__ = klass or self.__class__ |
| obj.model = self.model |
| obj.alias_refcount = self.alias_refcount.copy() |
| obj.alias_map = self.alias_map.copy() |
| obj.table_map = self.table_map.copy() |
| obj.join_map = self.join_map.copy() |
| obj.rev_join_map = self.rev_join_map.copy() |
| obj.quote_cache = {} |
| obj.default_cols = self.default_cols |
| obj.default_ordering = self.default_ordering |
| obj.standard_ordering = self.standard_ordering |
| obj.included_inherited_models = self.included_inherited_models.copy() |
| obj.ordering_aliases = [] |
| obj.select_fields = self.select_fields[:] |
| obj.related_select_fields = self.related_select_fields[:] |
| obj.dupe_avoidance = self.dupe_avoidance.copy() |
| obj.select = self.select[:] |
| obj.tables = self.tables[:] |
| obj.where = deepcopy(self.where, memo=memo) |
| obj.where_class = self.where_class |
| if self.group_by is None: |
| obj.group_by = None |
| else: |
| obj.group_by = self.group_by[:] |
| obj.having = deepcopy(self.having, memo=memo) |
| obj.order_by = self.order_by[:] |
| obj.low_mark, obj.high_mark = self.low_mark, self.high_mark |
| obj.distinct = self.distinct |
| obj.select_related = self.select_related |
| obj.related_select_cols = [] |
| obj.aggregates = deepcopy(self.aggregates, memo=memo) |
| if self.aggregate_select_mask is None: |
| obj.aggregate_select_mask = None |
| else: |
| obj.aggregate_select_mask = self.aggregate_select_mask.copy() |
| # _aggregate_select_cache cannot be copied, as doing so breaks the |
| # (necessary) state in which both aggregates and |
| # _aggregate_select_cache point to the same underlying objects. |
| # It will get re-populated in the cloned queryset the next time it's |
| # used. |
| obj._aggregate_select_cache = None |
| obj.max_depth = self.max_depth |
| obj.extra = self.extra.copy() |
| if self.extra_select_mask is None: |
| obj.extra_select_mask = None |
| else: |
| obj.extra_select_mask = self.extra_select_mask.copy() |
| if self._extra_select_cache is None: |
| obj._extra_select_cache = None |
| else: |
| obj._extra_select_cache = self._extra_select_cache.copy() |
| obj.extra_tables = self.extra_tables |
| obj.extra_order_by = self.extra_order_by |
| obj.deferred_loading = deepcopy(self.deferred_loading, memo=memo) |
| if self.filter_is_sticky and self.used_aliases: |
| obj.used_aliases = self.used_aliases.copy() |
| else: |
| obj.used_aliases = set() |
| obj.filter_is_sticky = False |
| obj.__dict__.update(kwargs) |
| if hasattr(obj, '_setup_query'): |
| obj._setup_query() |
| return obj |
| |
| def convert_values(self, value, field, connection): |
| """Convert the database-returned value into a type that is consistent |
| across database backends. |
| |
| By default, this defers to the underlying backend operations, but |
| it can be overridden by Query classes for specific backends. |
| """ |
| return connection.ops.convert_values(value, field) |
| |
| def resolve_aggregate(self, value, aggregate, connection): |
| """Resolve the value of aggregates returned by the database to |
| consistent (and reasonable) types. |
| |
| This is required because of the predisposition of certain backends |
| to return Decimal and long types when they are not needed. |
| """ |
| if value is None: |
| if aggregate.is_ordinal: |
| return 0 |
| # Return None as-is |
| return value |
| elif aggregate.is_ordinal: |
| # Any ordinal aggregate (e.g., count) returns an int |
| return int(value) |
| elif aggregate.is_computed: |
| # Any computed aggregate (e.g., avg) returns a float |
| return float(value) |
| else: |
| # Return value depends on the type of the field being processed. |
| return self.convert_values(value, aggregate.field, connection) |
| |
| def get_aggregation(self, using): |
| """ |
| Returns the dictionary with the values of the existing aggregations. |
| """ |
| if not self.aggregate_select: |
| return {} |
| |
| # If there is a group by clause, aggregating does not add useful |
| # information but retrieves only the first row. Aggregate |
| # over the subquery instead. |
| if self.group_by is not None: |
| from django.db.models.sql.subqueries import AggregateQuery |
| query = AggregateQuery(self.model) |
| |
| obj = self.clone() |
| |
| # Remove any aggregates marked for reduction from the subquery |
| # and move them to the outer AggregateQuery. |
| for alias, aggregate in self.aggregate_select.items(): |
| if aggregate.is_summary: |
| query.aggregate_select[alias] = aggregate |
| del obj.aggregate_select[alias] |
| |
| try: |
| query.add_subquery(obj, using) |
| except EmptyResultSet: |
| return dict( |
| (alias, None) |
| for alias in query.aggregate_select |
| ) |
| else: |
| query = self |
| self.select = [] |
| self.default_cols = False |
| self.extra = {} |
| self.remove_inherited_models() |
| |
| query.clear_ordering(True) |
| query.clear_limits() |
| query.select_related = False |
| query.related_select_cols = [] |
| query.related_select_fields = [] |
| |
| result = query.get_compiler(using).execute_sql(SINGLE) |
| if result is None: |
| result = [None for q in query.aggregate_select.items()] |
| |
| return dict([ |
| (alias, self.resolve_aggregate(val, aggregate, connection=connections[using])) |
| for (alias, aggregate), val |
| in zip(query.aggregate_select.items(), result) |
| ]) |
| |
| def get_count(self, using): |
| """ |
| Performs a COUNT() query using the current filter constraints. |
| """ |
| obj = self.clone() |
| if len(self.select) > 1 or self.aggregate_select: |
| # If a select clause exists, then the query has already started to |
| # specify the columns that are to be returned. |
| # In this case, we need to use a subquery to evaluate the count. |
| from django.db.models.sql.subqueries import AggregateQuery |
| subquery = obj |
| subquery.clear_ordering(True) |
| subquery.clear_limits() |
| |
| obj = AggregateQuery(obj.model) |
| try: |
| obj.add_subquery(subquery, using=using) |
| except EmptyResultSet: |
| # add_subquery evaluates the query, if it's an EmptyResultSet |
| # then there are can be no results, and therefore there the |
| # count is obviously 0 |
| return 0 |
| |
| obj.add_count_column() |
| number = obj.get_aggregation(using=using)[None] |
| |
| # Apply offset and limit constraints manually, since using LIMIT/OFFSET |
| # in SQL (in variants that provide them) doesn't change the COUNT |
| # output. |
| number = max(0, number - self.low_mark) |
| if self.high_mark is not None: |
| number = min(number, self.high_mark - self.low_mark) |
| |
| return number |
| |
| def has_results(self, using): |
| q = self.clone() |
| q.add_extra({'a': 1}, None, None, None, None, None) |
| q.select = [] |
| q.select_fields = [] |
| q.default_cols = False |
| q.select_related = False |
| q.set_extra_mask(('a',)) |
| q.set_aggregate_mask(()) |
| q.clear_ordering(True) |
| q.set_limits(high=1) |
| compiler = q.get_compiler(using=using) |
| return bool(compiler.execute_sql(SINGLE)) |
| |
| def combine(self, rhs, connector): |
| """ |
| Merge the 'rhs' query into the current one (with any 'rhs' effects |
| being applied *after* (that is, "to the right of") anything in the |
| current query. 'rhs' is not modified during a call to this function. |
| |
| The 'connector' parameter describes how to connect filters from the |
| 'rhs' query. |
| """ |
| assert self.model == rhs.model, \ |
| "Cannot combine queries on two different base models." |
| assert self.can_filter(), \ |
| "Cannot combine queries once a slice has been taken." |
| assert self.distinct == rhs.distinct, \ |
| "Cannot combine a unique query with a non-unique query." |
| |
| self.remove_inherited_models() |
| # Work out how to relabel the rhs aliases, if necessary. |
| change_map = {} |
| used = set() |
| conjunction = (connector == AND) |
| first = True |
| for alias in rhs.tables: |
| if not rhs.alias_refcount[alias]: |
| # An unused alias. |
| continue |
| promote = (rhs.alias_map[alias][JOIN_TYPE] == self.LOUTER) |
| new_alias = self.join(rhs.rev_join_map[alias], |
| (conjunction and not first), used, promote, not conjunction) |
| used.add(new_alias) |
| change_map[alias] = new_alias |
| first = False |
| |
| # So that we don't exclude valid results in an "or" query combination, |
| # the first join that is exclusive to the lhs (self) must be converted |
| # to an outer join. |
| if not conjunction: |
| for alias in self.tables[1:]: |
| if self.alias_refcount[alias] == 1: |
| self.promote_alias(alias, True) |
| break |
| |
| # Now relabel a copy of the rhs where-clause and add it to the current |
| # one. |
| if rhs.where: |
| w = deepcopy(rhs.where) |
| w.relabel_aliases(change_map) |
| if not self.where: |
| # Since 'self' matches everything, add an explicit "include |
| # everything" where-constraint so that connections between the |
| # where clauses won't exclude valid results. |
| self.where.add(EverythingNode(), AND) |
| elif self.where: |
| # rhs has an empty where clause. |
| w = self.where_class() |
| w.add(EverythingNode(), AND) |
| else: |
| w = self.where_class() |
| self.where.add(w, connector) |
| |
| # Selection columns and extra extensions are those provided by 'rhs'. |
| self.select = [] |
| for col in rhs.select: |
| if isinstance(col, (list, tuple)): |
| self.select.append((change_map.get(col[0], col[0]), col[1])) |
| else: |
| item = deepcopy(col) |
| item.relabel_aliases(change_map) |
| self.select.append(item) |
| self.select_fields = rhs.select_fields[:] |
| |
| if connector == OR: |
| # It would be nice to be able to handle this, but the queries don't |
| # really make sense (or return consistent value sets). Not worth |
| # the extra complexity when you can write a real query instead. |
| if self.extra and rhs.extra: |
| raise ValueError("When merging querysets using 'or', you " |
| "cannot have extra(select=...) on both sides.") |
| self.extra.update(rhs.extra) |
| extra_select_mask = set() |
| if self.extra_select_mask is not None: |
| extra_select_mask.update(self.extra_select_mask) |
| if rhs.extra_select_mask is not None: |
| extra_select_mask.update(rhs.extra_select_mask) |
| if extra_select_mask: |
| self.set_extra_mask(extra_select_mask) |
| self.extra_tables += rhs.extra_tables |
| |
| # Ordering uses the 'rhs' ordering, unless it has none, in which case |
| # the current ordering is used. |
| self.order_by = rhs.order_by and rhs.order_by[:] or self.order_by |
| self.extra_order_by = rhs.extra_order_by or self.extra_order_by |
| |
| def deferred_to_data(self, target, callback): |
| """ |
| Converts the self.deferred_loading data structure to an alternate data |
| structure, describing the field that *will* be loaded. This is used to |
| compute the columns to select from the database and also by the |
| QuerySet class to work out which fields are being initialised on each |
| model. Models that have all their fields included aren't mentioned in |
| the result, only those that have field restrictions in place. |
| |
| The "target" parameter is the instance that is populated (in place). |
| The "callback" is a function that is called whenever a (model, field) |
| pair need to be added to "target". It accepts three parameters: |
| "target", and the model and list of fields being added for that model. |
| """ |
| field_names, defer = self.deferred_loading |
| if not field_names: |
| return |
| columns = set() |
| orig_opts = self.model._meta |
| seen = {} |
| must_include = {self.model: set([orig_opts.pk])} |
| for field_name in field_names: |
| parts = field_name.split(LOOKUP_SEP) |
| cur_model = self.model |
| opts = orig_opts |
| for name in parts[:-1]: |
| old_model = cur_model |
| source = opts.get_field_by_name(name)[0] |
| cur_model = opts.get_field_by_name(name)[0].rel.to |
| opts = cur_model._meta |
| # Even if we're "just passing through" this model, we must add |
| # both the current model's pk and the related reference field |
| # to the things we select. |
| must_include[old_model].add(source) |
| add_to_dict(must_include, cur_model, opts.pk) |
| field, model, _, _ = opts.get_field_by_name(parts[-1]) |
| if model is None: |
| model = cur_model |
| add_to_dict(seen, model, field) |
| |
| if defer: |
| # We need to load all fields for each model, except those that |
| # appear in "seen" (for all models that appear in "seen"). The only |
| # slight complexity here is handling fields that exist on parent |
| # models. |
| workset = {} |
| for model, values in seen.iteritems(): |
| for field, m in model._meta.get_fields_with_model(): |
| if field in values: |
| continue |
| add_to_dict(workset, m or model, field) |
| for model, values in must_include.iteritems(): |
| # If we haven't included a model in workset, we don't add the |
| # corresponding must_include fields for that model, since an |
| # empty set means "include all fields". That's why there's no |
| # "else" branch here. |
| if model in workset: |
| workset[model].update(values) |
| for model, values in workset.iteritems(): |
| callback(target, model, values) |
| else: |
| for model, values in must_include.iteritems(): |
| if model in seen: |
| seen[model].update(values) |
| else: |
| # As we've passed through this model, but not explicitly |
| # included any fields, we have to make sure it's mentioned |
| # so that only the "must include" fields are pulled in. |
| seen[model] = values |
| # Now ensure that every model in the inheritance chain is mentioned |
| # in the parent list. Again, it must be mentioned to ensure that |
| # only "must include" fields are pulled in. |
| for model in orig_opts.get_parent_list(): |
| if model not in seen: |
| seen[model] = set() |
| for model, values in seen.iteritems(): |
| callback(target, model, values) |
| |
| |
| def deferred_to_columns_cb(self, target, model, fields): |
| """ |
| Callback used by deferred_to_columns(). The "target" parameter should |
| be a set instance. |
| """ |
| table = model._meta.db_table |
| if table not in target: |
| target[table] = set() |
| for field in fields: |
| target[table].add(field.column) |
| |
| |
| def table_alias(self, table_name, create=False): |
| """ |
| Returns a table alias for the given table_name and whether this is a |
| new alias or not. |
| |
| If 'create' is true, a new alias is always created. Otherwise, the |
| most recently created alias for the table (if one exists) is reused. |
| """ |
| current = self.table_map.get(table_name) |
| if not create and current: |
| alias = current[0] |
| self.alias_refcount[alias] += 1 |
| return alias, False |
| |
| # Create a new alias for this table. |
| if current: |
| alias = '%s%d' % (self.alias_prefix, len(self.alias_map) + 1) |
| current.append(alias) |
| else: |
| # The first occurence of a table uses the table name directly. |
| alias = table_name |
| self.table_map[alias] = [alias] |
| self.alias_refcount[alias] = 1 |
| self.tables.append(alias) |
| return alias, True |
| |
| def ref_alias(self, alias): |
| """ Increases the reference count for this alias. """ |
| self.alias_refcount[alias] += 1 |
| |
| def unref_alias(self, alias): |
| """ Decreases the reference count for this alias. """ |
| self.alias_refcount[alias] -= 1 |
| |
| def promote_alias(self, alias, unconditional=False): |
| """ |
| Promotes the join type of an alias to an outer join if it's possible |
| for the join to contain NULL values on the left. If 'unconditional' is |
| False, the join is only promoted if it is nullable, otherwise it is |
| always promoted. |
| |
| Returns True if the join was promoted. |
| """ |
| if ((unconditional or self.alias_map[alias][NULLABLE]) and |
| self.alias_map[alias][JOIN_TYPE] != self.LOUTER): |
| data = list(self.alias_map[alias]) |
| data[JOIN_TYPE] = self.LOUTER |
| self.alias_map[alias] = tuple(data) |
| return True |
| return False |
| |
| def promote_alias_chain(self, chain, must_promote=False): |
| """ |
| Walks along a chain of aliases, promoting the first nullable join and |
| any joins following that. If 'must_promote' is True, all the aliases in |
| the chain are promoted. |
| """ |
| for alias in chain: |
| if self.promote_alias(alias, must_promote): |
| must_promote = True |
| |
| def promote_unused_aliases(self, initial_refcounts, used_aliases): |
| """ |
| Given a "before" copy of the alias_refcounts dictionary (as |
| 'initial_refcounts') and a collection of aliases that may have been |
| changed or created, works out which aliases have been created since |
| then and which ones haven't been used and promotes all of those |
| aliases, plus any children of theirs in the alias tree, to outer joins. |
| """ |
| # FIXME: There's some (a lot of!) overlap with the similar OR promotion |
| # in add_filter(). It's not quite identical, but is very similar. So |
| # pulling out the common bits is something for later. |
| considered = {} |
| for alias in self.tables: |
| if alias not in used_aliases: |
| continue |
| if (alias not in initial_refcounts or |
| self.alias_refcount[alias] == initial_refcounts[alias]): |
| parent = self.alias_map[alias][LHS_ALIAS] |
| must_promote = considered.get(parent, False) |
| promoted = self.promote_alias(alias, must_promote) |
| considered[alias] = must_promote or promoted |
| |
| def change_aliases(self, change_map): |
| """ |
| Changes the aliases in change_map (which maps old-alias -> new-alias), |
| relabelling any references to them in select columns and the where |
| clause. |
| """ |
| assert set(change_map.keys()).intersection(set(change_map.values())) == set() |
| |
| # 1. Update references in "select" (normal columns plus aliases), |
| # "group by", "where" and "having". |
| self.where.relabel_aliases(change_map) |
| self.having.relabel_aliases(change_map) |
| for columns in [self.select, self.group_by or []]: |
| for pos, col in enumerate(columns): |
| if isinstance(col, (list, tuple)): |
| old_alias = col[0] |
| columns[pos] = (change_map.get(old_alias, old_alias), col[1]) |
| else: |
| col.relabel_aliases(change_map) |
| for mapping in [self.aggregates]: |
| for key, col in mapping.items(): |
| if isinstance(col, (list, tuple)): |
| old_alias = col[0] |
| mapping[key] = (change_map.get(old_alias, old_alias), col[1]) |
| else: |
| col.relabel_aliases(change_map) |
| |
| # 2. Rename the alias in the internal table/alias datastructures. |
| for old_alias, new_alias in change_map.iteritems(): |
| alias_data = list(self.alias_map[old_alias]) |
| alias_data[RHS_ALIAS] = new_alias |
| |
| t = self.rev_join_map[old_alias] |
| data = list(self.join_map[t]) |
| data[data.index(old_alias)] = new_alias |
| self.join_map[t] = tuple(data) |
| self.rev_join_map[new_alias] = t |
| del self.rev_join_map[old_alias] |
| self.alias_refcount[new_alias] = self.alias_refcount[old_alias] |
| del self.alias_refcount[old_alias] |
| self.alias_map[new_alias] = tuple(alias_data) |
| del self.alias_map[old_alias] |
| |
| table_aliases = self.table_map[alias_data[TABLE_NAME]] |
| for pos, alias in enumerate(table_aliases): |
| if alias == old_alias: |
| table_aliases[pos] = new_alias |
| break |
| for pos, alias in enumerate(self.tables): |
| if alias == old_alias: |
| self.tables[pos] = new_alias |
| break |
| for key, alias in self.included_inherited_models.items(): |
| if alias in change_map: |
| self.included_inherited_models[key] = change_map[alias] |
| |
| # 3. Update any joins that refer to the old alias. |
| for alias, data in self.alias_map.iteritems(): |
| lhs = data[LHS_ALIAS] |
| if lhs in change_map: |
| data = list(data) |
| data[LHS_ALIAS] = change_map[lhs] |
| self.alias_map[alias] = tuple(data) |
| |
| def bump_prefix(self, exceptions=()): |
| """ |
| Changes the alias prefix to the next letter in the alphabet and |
| relabels all the aliases. Even tables that previously had no alias will |
| get an alias after this call (it's mostly used for nested queries and |
| the outer query will already be using the non-aliased table name). |
| |
| Subclasses who create their own prefix should override this method to |
| produce a similar result (a new prefix and relabelled aliases). |
| |
| The 'exceptions' parameter is a container that holds alias names which |
| should not be changed. |
| """ |
| current = ord(self.alias_prefix) |
| assert current < ord('Z') |
| prefix = chr(current + 1) |
| self.alias_prefix = prefix |
| change_map = {} |
| for pos, alias in enumerate(self.tables): |
| if alias in exceptions: |
| continue |
| new_alias = '%s%d' % (prefix, pos) |
| change_map[alias] = new_alias |
| self.tables[pos] = new_alias |
| self.change_aliases(change_map) |
| |
| def get_initial_alias(self): |
| """ |
| Returns the first alias for this query, after increasing its reference |
| count. |
| """ |
| if self.tables: |
| alias = self.tables[0] |
| self.ref_alias(alias) |
| else: |
| alias = self.join((None, self.model._meta.db_table, None, None)) |
| return alias |
| |
| def count_active_tables(self): |
| """ |
| Returns the number of tables in this query with a non-zero reference |
| count. |
| """ |
| return len([1 for count in self.alias_refcount.itervalues() if count]) |
| |
| def join(self, connection, always_create=False, exclusions=(), |
| promote=False, outer_if_first=False, nullable=False, reuse=None): |
| """ |
| Returns an alias for the join in 'connection', either reusing an |
| existing alias for that join or creating a new one. 'connection' is a |
| tuple (lhs, table, lhs_col, col) where 'lhs' is either an existing |
| table alias or a table name. The join correspods to the SQL equivalent |
| of:: |
| |
| lhs.lhs_col = table.col |
| |
| If 'always_create' is True and 'reuse' is None, a new alias is always |
| created, regardless of whether one already exists or not. If |
| 'always_create' is True and 'reuse' is a set, an alias in 'reuse' that |
| matches the connection will be returned, if possible. If |
| 'always_create' is False, the first existing alias that matches the |
| 'connection' is returned, if any. Otherwise a new join is created. |
| |
| If 'exclusions' is specified, it is something satisfying the container |
| protocol ("foo in exclusions" must work) and specifies a list of |
| aliases that should not be returned, even if they satisfy the join. |
| |
| If 'promote' is True, the join type for the alias will be LOUTER (if |
| the alias previously existed, the join type will be promoted from INNER |
| to LOUTER, if necessary). |
| |
| If 'outer_if_first' is True and a new join is created, it will have the |
| LOUTER join type. This is used when joining certain types of querysets |
| and Q-objects together. |
| |
| If 'nullable' is True, the join can potentially involve NULL values and |
| is a candidate for promotion (to "left outer") when combining querysets. |
| """ |
| lhs, table, lhs_col, col = connection |
| if lhs in self.alias_map: |
| lhs_table = self.alias_map[lhs][TABLE_NAME] |
| else: |
| lhs_table = lhs |
| |
| if reuse and always_create and table in self.table_map: |
| # Convert the 'reuse' to case to be "exclude everything but the |
| # reusable set, minus exclusions, for this table". |
| exclusions = set(self.table_map[table]).difference(reuse).union(set(exclusions)) |
| always_create = False |
| t_ident = (lhs_table, table, lhs_col, col) |
| if not always_create: |
| for alias in self.join_map.get(t_ident, ()): |
| if alias not in exclusions: |
| if lhs_table and not self.alias_refcount[self.alias_map[alias][LHS_ALIAS]]: |
| # The LHS of this join tuple is no longer part of the |
| # query, so skip this possibility. |
| continue |
| if self.alias_map[alias][LHS_ALIAS] != lhs: |
| continue |
| self.ref_alias(alias) |
| if promote: |
| self.promote_alias(alias) |
| return alias |
| |
| # No reuse is possible, so we need a new alias. |
| alias, _ = self.table_alias(table, True) |
| if not lhs: |
| # Not all tables need to be joined to anything. No join type |
| # means the later columns are ignored. |
| join_type = None |
| elif promote or outer_if_first: |
| join_type = self.LOUTER |
| else: |
| join_type = self.INNER |
| join = (table, alias, join_type, lhs, lhs_col, col, nullable) |
| self.alias_map[alias] = join |
| if t_ident in self.join_map: |
| self.join_map[t_ident] += (alias,) |
| else: |
| self.join_map[t_ident] = (alias,) |
| self.rev_join_map[alias] = t_ident |
| return alias |
| |
| def setup_inherited_models(self): |
| """ |
| If the model that is the basis for this QuerySet inherits other models, |
| we need to ensure that those other models have their tables included in |
| the query. |
| |
| We do this as a separate step so that subclasses know which |
| tables are going to be active in the query, without needing to compute |
| all the select columns (this method is called from pre_sql_setup(), |
| whereas column determination is a later part, and side-effect, of |
| as_sql()). |
| """ |
| opts = self.model._meta |
| root_alias = self.tables[0] |
| seen = {None: root_alias} |
| |
| # Skip all proxy to the root proxied model |
| proxied_model = get_proxied_model(opts) |
| |
| for field, model in opts.get_fields_with_model(): |
| if model not in seen: |
| if model is proxied_model: |
| seen[model] = root_alias |
| else: |
| link_field = opts.get_ancestor_link(model) |
| seen[model] = self.join((root_alias, model._meta.db_table, |
| link_field.column, model._meta.pk.column)) |
| self.included_inherited_models = seen |
| |
| def remove_inherited_models(self): |
| """ |
| Undoes the effects of setup_inherited_models(). Should be called |
| whenever select columns (self.select) are set explicitly. |
| """ |
| for key, alias in self.included_inherited_models.items(): |
| if key: |
| self.unref_alias(alias) |
| self.included_inherited_models = {} |
| |
| |
| def add_aggregate(self, aggregate, model, alias, is_summary): |
| """ |
| Adds a single aggregate expression to the Query |
| """ |
| opts = model._meta |
| field_list = aggregate.lookup.split(LOOKUP_SEP) |
| if len(field_list) == 1 and aggregate.lookup in self.aggregates: |
| # Aggregate is over an annotation |
| field_name = field_list[0] |
| col = field_name |
| source = self.aggregates[field_name] |
| if not is_summary: |
| raise FieldError("Cannot compute %s('%s'): '%s' is an aggregate" % ( |
| aggregate.name, field_name, field_name)) |
| elif ((len(field_list) > 1) or |
| (field_list[0] not in [i.name for i in opts.fields]) or |
| self.group_by is None or |
| not is_summary): |
| # If: |
| # - the field descriptor has more than one part (foo__bar), or |
| # - the field descriptor is referencing an m2m/m2o field, or |
| # - this is a reference to a model field (possibly inherited), or |
| # - this is an annotation over a model field |
| # then we need to explore the joins that are required. |
| |
| field, source, opts, join_list, last, _ = self.setup_joins( |
| field_list, opts, self.get_initial_alias(), False) |
| |
| # Process the join chain to see if it can be trimmed |
| col, _, join_list = self.trim_joins(source, join_list, last, False) |
| |
| # If the aggregate references a model or field that requires a join, |
| # those joins must be LEFT OUTER - empty join rows must be returned |
| # in order for zeros to be returned for those aggregates. |
| for column_alias in join_list: |
| self.promote_alias(column_alias, unconditional=True) |
| |
| col = (join_list[-1], col) |
| else: |
| # The simplest cases. No joins required - |
| # just reference the provided column alias. |
| field_name = field_list[0] |
| source = opts.get_field(field_name) |
| col = field_name |
| |
| # Add the aggregate to the query |
| aggregate.add_to_query(self, alias, col=col, source=source, is_summary=is_summary) |
| |
| def add_filter(self, filter_expr, connector=AND, negate=False, trim=False, |
| can_reuse=None, process_extras=True): |
| """ |
| Add a single filter to the query. The 'filter_expr' is a pair: |
| (filter_string, value). E.g. ('name__contains', 'fred') |
| |
| If 'negate' is True, this is an exclude() filter. It's important to |
| note that this method does not negate anything in the where-clause |
| object when inserting the filter constraints. This is because negated |
| filters often require multiple calls to add_filter() and the negation |
| should only happen once. So the caller is responsible for this (the |
| caller will normally be add_q(), so that as an example). |
| |
| If 'trim' is True, we automatically trim the final join group (used |
| internally when constructing nested queries). |
| |
| If 'can_reuse' is a set, we are processing a component of a |
| multi-component filter (e.g. filter(Q1, Q2)). In this case, 'can_reuse' |
| will be a set of table aliases that can be reused in this filter, even |
| if we would otherwise force the creation of new aliases for a join |
| (needed for nested Q-filters). The set is updated by this method. |
| |
| If 'process_extras' is set, any extra filters returned from the table |
| joining process will be processed. This parameter is set to False |
| during the processing of extra filters to avoid infinite recursion. |
| """ |
| arg, value = filter_expr |
| parts = arg.split(LOOKUP_SEP) |
| if not parts: |
| raise FieldError("Cannot parse keyword query %r" % arg) |
| |
| # Work out the lookup type and remove it from 'parts', if necessary. |
| if len(parts) == 1 or parts[-1] not in self.query_terms: |
| lookup_type = 'exact' |
| else: |
| lookup_type = parts.pop() |
| |
| # By default, this is a WHERE clause. If an aggregate is referenced |
| # in the value, the filter will be promoted to a HAVING |
| having_clause = False |
| |
| # Interpret '__exact=None' as the sql 'is NULL'; otherwise, reject all |
| # uses of None as a query value. |
| if value is None: |
| if lookup_type != 'exact': |
| raise ValueError("Cannot use None as a query value") |
| lookup_type = 'isnull' |
| value = True |
| elif callable(value): |
| value = value() |
| elif hasattr(value, 'evaluate'): |
| # If value is a query expression, evaluate it |
| value = SQLEvaluator(value, self) |
| having_clause = value.contains_aggregate |
| |
| for alias, aggregate in self.aggregates.items(): |
| if alias == parts[0]: |
| entry = self.where_class() |
| entry.add((aggregate, lookup_type, value), AND) |
| if negate: |
| entry.negate() |
| self.having.add(entry, AND) |
| return |
| |
| opts = self.get_meta() |
| alias = self.get_initial_alias() |
| allow_many = trim or not negate |
| |
| try: |
| field, target, opts, join_list, last, extra_filters = self.setup_joins( |
| parts, opts, alias, True, allow_many, can_reuse=can_reuse, |
| negate=negate, process_extras=process_extras) |
| except MultiJoin, e: |
| self.split_exclude(filter_expr, LOOKUP_SEP.join(parts[:e.level]), |
| can_reuse) |
| return |
| |
| if (lookup_type == 'isnull' and value is True and not negate and |
| len(join_list) > 1): |
| # If the comparison is against NULL, we may need to use some left |
| # outer joins when creating the join chain. This is only done when |
| # needed, as it's less efficient at the database level. |
| self.promote_alias_chain(join_list) |
| |
| # Process the join list to see if we can remove any inner joins from |
| # the far end (fewer tables in a query is better). |
| col, alias, join_list = self.trim_joins(target, join_list, last, trim) |
| |
| if connector == OR: |
| # Some joins may need to be promoted when adding a new filter to a |
| # disjunction. We walk the list of new joins and where it diverges |
| # from any previous joins (ref count is 1 in the table list), we |
| # make the new additions (and any existing ones not used in the new |
| # join list) an outer join. |
| join_it = iter(join_list) |
| table_it = iter(self.tables) |
| join_it.next(), table_it.next() |
| table_promote = False |
| join_promote = False |
| for join in join_it: |
| table = table_it.next() |
| if join == table and self.alias_refcount[join] > 1: |
| continue |
| join_promote = self.promote_alias(join) |
| if table != join: |
| table_promote = self.promote_alias(table) |
| break |
| self.promote_alias_chain(join_it, join_promote) |
| self.promote_alias_chain(table_it, table_promote) |
| |
| |
| if having_clause: |
| if (alias, col) not in self.group_by: |
| self.group_by.append((alias, col)) |
| self.having.add((Constraint(alias, col, field), lookup_type, value), |
| connector) |
| else: |
| self.where.add((Constraint(alias, col, field), lookup_type, value), |
| connector) |
| |
| if negate: |
| self.promote_alias_chain(join_list) |
| if lookup_type != 'isnull': |
| if len(join_list) > 1: |
| for alias in join_list: |
| if self.alias_map[alias][JOIN_TYPE] == self.LOUTER: |
| j_col = self.alias_map[alias][RHS_JOIN_COL] |
| entry = self.where_class() |
| entry.add( |
| (Constraint(alias, j_col, None), 'isnull', True), |
| AND |
| ) |
| entry.negate() |
| self.where.add(entry, AND) |
| break |
| if not (lookup_type == 'in' |
| and not hasattr(value, 'as_sql') |
| and not hasattr(value, '_as_sql') |
| and not value) and field.null: |
| # Leaky abstraction artifact: We have to specifically |
| # exclude the "foo__in=[]" case from this handling, because |
| # it's short-circuited in the Where class. |
| # We also need to handle the case where a subquery is provided |
| self.where.add((Constraint(alias, col, None), 'isnull', False), AND) |
| |
| if can_reuse is not None: |
| can_reuse.update(join_list) |
| if process_extras: |
| for filter in extra_filters: |
| self.add_filter(filter, negate=negate, can_reuse=can_reuse, |
| process_extras=False) |
| |
| def add_q(self, q_object, used_aliases=None): |
| """ |
| Adds a Q-object to the current filter. |
| |
| Can also be used to add anything that has an 'add_to_query()' method. |
| """ |
| if used_aliases is None: |
| used_aliases = self.used_aliases |
| if hasattr(q_object, 'add_to_query'): |
| # Complex custom objects are responsible for adding themselves. |
| q_object.add_to_query(self, used_aliases) |
| else: |
| if self.where and q_object.connector != AND and len(q_object) > 1: |
| self.where.start_subtree(AND) |
| subtree = True |
| else: |
| subtree = False |
| connector = AND |
| for child in q_object.children: |
| if connector == OR: |
| refcounts_before = self.alias_refcount.copy() |
| self.where.start_subtree(connector) |
| if isinstance(child, Node): |
| self.add_q(child, used_aliases) |
| else: |
| self.add_filter(child, connector, q_object.negated, |
| can_reuse=used_aliases) |
| self.where.end_subtree() |
| if connector == OR: |
| # Aliases that were newly added or not used at all need to |
| # be promoted to outer joins if they are nullable relations. |
| # (they shouldn't turn the whole conditional into the empty |
| # set just because they don't match anything). |
| self.promote_unused_aliases(refcounts_before, used_aliases) |
| connector = q_object.connector |
| if q_object.negated: |
| self.where.negate() |
| if subtree: |
| self.where.end_subtree() |
| if self.filter_is_sticky: |
| self.used_aliases = used_aliases |
| |
| def setup_joins(self, names, opts, alias, dupe_multis, allow_many=True, |
| allow_explicit_fk=False, can_reuse=None, negate=False, |
| process_extras=True): |
| """ |
| Compute the necessary table joins for the passage through the fields |
| given in 'names'. 'opts' is the Options class for the current model |
| (which gives the table we are joining to), 'alias' is the alias for the |
| table we are joining to. If dupe_multis is True, any many-to-many or |
| many-to-one joins will always create a new alias (necessary for |
| disjunctive filters). If can_reuse is not None, it's a list of aliases |
| that can be reused in these joins (nothing else can be reused in this |
| case). Finally, 'negate' is used in the same sense as for add_filter() |
| -- it indicates an exclude() filter, or something similar. It is only |
| passed in here so that it can be passed to a field's extra_filter() for |
| customised behaviour. |
| |
| Returns the final field involved in the join, the target database |
| column (used for any 'where' constraint), the final 'opts' value and the |
| list of tables joined. |
| """ |
| joins = [alias] |
| last = [0] |
| dupe_set = set() |
| exclusions = set() |
| extra_filters = [] |
| for pos, name in enumerate(names): |
| try: |
| exclusions.add(int_alias) |
| except NameError: |
| pass |
| exclusions.add(alias) |
| last.append(len(joins)) |
| if name == 'pk': |
| name = opts.pk.name |
| try: |
| field, model, direct, m2m = opts.get_field_by_name(name) |
| except FieldDoesNotExist: |
| for f in opts.fields: |
| if allow_explicit_fk and name == f.attname: |
| # XXX: A hack to allow foo_id to work in values() for |
| # backwards compatibility purposes. If we dropped that |
| # feature, this could be removed. |
| field, model, direct, m2m = opts.get_field_by_name(f.name) |
| break |
| else: |
| names = opts.get_all_field_names() + self.aggregate_select.keys() |
| raise FieldError("Cannot resolve keyword %r into field. " |
| "Choices are: %s" % (name, ", ".join(names))) |
| |
| if not allow_many and (m2m or not direct): |
| for alias in joins: |
| self.unref_alias(alias) |
| raise MultiJoin(pos + 1) |
| if model: |
| # The field lives on a base class of the current model. |
| # Skip the chain of proxy to the concrete proxied model |
| proxied_model = get_proxied_model(opts) |
| |
| for int_model in opts.get_base_chain(model): |
| if int_model is proxied_model: |
| opts = int_model._meta |
| else: |
| lhs_col = opts.parents[int_model].column |
| dedupe = lhs_col in opts.duplicate_targets |
| if dedupe: |
| exclusions.update(self.dupe_avoidance.get( |
| (id(opts), lhs_col), ())) |
| dupe_set.add((opts, lhs_col)) |
| opts = int_model._meta |
| alias = self.join((alias, opts.db_table, lhs_col, |
| opts.pk.column), exclusions=exclusions) |
| joins.append(alias) |
| exclusions.add(alias) |
| for (dupe_opts, dupe_col) in dupe_set: |
| self.update_dupe_avoidance(dupe_opts, dupe_col, |
| alias) |
| cached_data = opts._join_cache.get(name) |
| orig_opts = opts |
| dupe_col = direct and field.column or field.field.column |
| dedupe = dupe_col in opts.duplicate_targets |
| if dupe_set or dedupe: |
| if dedupe: |
| dupe_set.add((opts, dupe_col)) |
| exclusions.update(self.dupe_avoidance.get((id(opts), dupe_col), |
| ())) |
| |
| if process_extras and hasattr(field, 'extra_filters'): |
| extra_filters.extend(field.extra_filters(names, pos, negate)) |
| if direct: |
| if m2m: |
| # Many-to-many field defined on the current model. |
| if cached_data: |
| (table1, from_col1, to_col1, table2, from_col2, |
| to_col2, opts, target) = cached_data |
| else: |
| table1 = field.m2m_db_table() |
| from_col1 = opts.pk.column |
| to_col1 = field.m2m_column_name() |
| opts = field.rel.to._meta |
| table2 = opts.db_table |
| from_col2 = field.m2m_reverse_name() |
| to_col2 = opts.pk.column |
| target = opts.pk |
| orig_opts._join_cache[name] = (table1, from_col1, |
| to_col1, table2, from_col2, to_col2, opts, |
| target) |
| |
| int_alias = self.join((alias, table1, from_col1, to_col1), |
| dupe_multis, exclusions, nullable=True, |
| reuse=can_reuse) |
| if int_alias == table2 and from_col2 == to_col2: |
| joins.append(int_alias) |
| alias = int_alias |
| else: |
| alias = self.join( |
| (int_alias, table2, from_col2, to_col2), |
| dupe_multis, exclusions, nullable=True, |
| reuse=can_reuse) |
| joins.extend([int_alias, alias]) |
| elif field.rel: |
| # One-to-one or many-to-one field |
| if cached_data: |
| (table, from_col, to_col, opts, target) = cached_data |
| else: |
| opts = field.rel.to._meta |
| target = field.rel.get_related_field() |
| table = opts.db_table |
| from_col = field.column |
| to_col = target.column |
| orig_opts._join_cache[name] = (table, from_col, to_col, |
| opts, target) |
| |
| alias = self.join((alias, table, from_col, to_col), |
| exclusions=exclusions, nullable=field.null) |
| joins.append(alias) |
| else: |
| # Non-relation fields. |
| target = field |
| break |
| else: |
| orig_field = field |
| field = field.field |
| if m2m: |
| # Many-to-many field defined on the target model. |
| if cached_data: |
| (table1, from_col1, to_col1, table2, from_col2, |
| to_col2, opts, target) = cached_data |
| else: |
| table1 = field.m2m_db_table() |
| from_col1 = opts.pk.column |
| to_col1 = field.m2m_reverse_name() |
| opts = orig_field.opts |
| table2 = opts.db_table |
| from_col2 = field.m2m_column_name() |
| to_col2 = opts.pk.column |
| target = opts.pk |
| orig_opts._join_cache[name] = (table1, from_col1, |
| to_col1, table2, from_col2, to_col2, opts, |
| target) |
| |
| int_alias = self.join((alias, table1, from_col1, to_col1), |
| dupe_multis, exclusions, nullable=True, |
| reuse=can_reuse) |
| alias = self.join((int_alias, table2, from_col2, to_col2), |
| dupe_multis, exclusions, nullable=True, |
| reuse=can_reuse) |
| joins.extend([int_alias, alias]) |
| else: |
| # One-to-many field (ForeignKey defined on the target model) |
| if cached_data: |
| (table, from_col, to_col, opts, target) = cached_data |
| else: |
| local_field = opts.get_field_by_name( |
| field.rel.field_name)[0] |
| opts = orig_field.opts |
| table = opts.db_table |
| from_col = local_field.column |
| to_col = field.column |
| target = opts.pk |
| orig_opts._join_cache[name] = (table, from_col, to_col, |
| opts, target) |
| |
| alias = self.join((alias, table, from_col, to_col), |
| dupe_multis, exclusions, nullable=True, |
| reuse=can_reuse) |
| joins.append(alias) |
| |
| for (dupe_opts, dupe_col) in dupe_set: |
| try: |
| self.update_dupe_avoidance(dupe_opts, dupe_col, int_alias) |
| except NameError: |
| self.update_dupe_avoidance(dupe_opts, dupe_col, alias) |
| |
| if pos != len(names) - 1: |
| if pos == len(names) - 2: |
| raise FieldError("Join on field %r not permitted. Did you misspell %r for the lookup type?" % (name, names[pos + 1])) |
| else: |
| raise FieldError("Join on field %r not permitted." % name) |
| |
| return field, target, opts, joins, last, extra_filters |
| |
| def trim_joins(self, target, join_list, last, trim): |
| """ |
| Sometimes joins at the end of a multi-table sequence can be trimmed. If |
| the final join is against the same column as we are comparing against, |
| and is an inner join, we can go back one step in a join chain and |
| compare against the LHS of the join instead (and then repeat the |
| optimization). The result, potentially, involves less table joins. |
| |
| The 'target' parameter is the final field being joined to, 'join_list' |
| is the full list of join aliases. |
| |
| The 'last' list contains offsets into 'join_list', corresponding to |
| each component of the filter. Many-to-many relations, for example, add |
| two tables to the join list and we want to deal with both tables the |
| same way, so 'last' has an entry for the first of the two tables and |
| then the table immediately after the second table, in that case. |
| |
| The 'trim' parameter forces the final piece of the join list to be |
| trimmed before anything. See the documentation of add_filter() for |
| details about this. |
| |
| Returns the final active column and table alias and the new active |
| join_list. |
| """ |
| final = len(join_list) |
| penultimate = last.pop() |
| if penultimate == final: |
| penultimate = last.pop() |
| if trim and len(join_list) > 1: |
| extra = join_list[penultimate:] |
| join_list = join_list[:penultimate] |
| final = penultimate |
| penultimate = last.pop() |
| col = self.alias_map[extra[0]][LHS_JOIN_COL] |
| for alias in extra: |
| self.unref_alias(alias) |
| else: |
| col = target.column |
| alias = join_list[-1] |
| while final > 1: |
| join = self.alias_map[alias] |
| if col != join[RHS_JOIN_COL] or join[JOIN_TYPE] != self.INNER: |
| break |
| self.unref_alias(alias) |
| alias = join[LHS_ALIAS] |
| col = join[LHS_JOIN_COL] |
| join_list = join_list[:-1] |
| final -= 1 |
| if final == penultimate: |
| penultimate = last.pop() |
| return col, alias, join_list |
| |
| def update_dupe_avoidance(self, opts, col, alias): |
| """ |
| For a column that is one of multiple pointing to the same table, update |
| the internal data structures to note that this alias shouldn't be used |
| for those other columns. |
| """ |
| ident = id(opts) |
| for name in opts.duplicate_targets[col]: |
| try: |
| self.dupe_avoidance[ident, name].add(alias) |
| except KeyError: |
| self.dupe_avoidance[ident, name] = set([alias]) |
| |
| def split_exclude(self, filter_expr, prefix, can_reuse): |
| """ |
| When doing an exclude against any kind of N-to-many relation, we need |
| to use a subquery. This method constructs the nested query, given the |
| original exclude filter (filter_expr) and the portion up to the first |
| N-to-many relation field. |
| """ |
| query = Query(self.model) |
| query.add_filter(filter_expr, can_reuse=can_reuse) |
| query.bump_prefix() |
| query.clear_ordering(True) |
| query.set_start(prefix) |
| self.add_filter(('%s__in' % prefix, query), negate=True, trim=True, |
| can_reuse=can_reuse) |
| |
| # If there's more than one join in the inner query (before any initial |
| # bits were trimmed -- which means the last active table is more than |
| # two places into the alias list), we need to also handle the |
| # possibility that the earlier joins don't match anything by adding a |
| # comparison to NULL (e.g. in |
| # Tag.objects.exclude(parent__parent__name='t1'), a tag with no parent |
| # would otherwise be overlooked). |
| active_positions = [pos for (pos, count) in |
| enumerate(query.alias_refcount.itervalues()) if count] |
| if active_positions[-1] > 1: |
| self.add_filter(('%s__isnull' % prefix, False), negate=True, |
| trim=True, can_reuse=can_reuse) |
| |
| def set_limits(self, low=None, high=None): |
| """ |
| Adjusts the limits on the rows retrieved. We use low/high to set these, |
| as it makes it more Pythonic to read and write. When the SQL query is |
| created, they are converted to the appropriate offset and limit values. |
| |
| Any limits passed in here are applied relative to the existing |
| constraints. So low is added to the current low value and both will be |
| clamped to any existing high value. |
| """ |
| if high is not None: |
| if self.high_mark is not None: |
| self.high_mark = min(self.high_mark, self.low_mark + high) |
| else: |
| self.high_mark = self.low_mark + high |
| if low is not None: |
| if self.high_mark is not None: |
| self.low_mark = min(self.high_mark, self.low_mark + low) |
| else: |
| self.low_mark = self.low_mark + low |
| |
| def clear_limits(self): |
| """ |
| Clears any existing limits. |
| """ |
| self.low_mark, self.high_mark = 0, None |
| |
| def can_filter(self): |
| """ |
| Returns True if adding filters to this instance is still possible. |
| |
| Typically, this means no limits or offsets have been put on the results. |
| """ |
| return not self.low_mark and self.high_mark is None |
| |
| def clear_select_fields(self): |
| """ |
| Clears the list of fields to select (but not extra_select columns). |
| Some queryset types completely replace any existing list of select |
| columns. |
| """ |
| self.select = [] |
| self.select_fields = [] |
| |
| def add_fields(self, field_names, allow_m2m=True): |
| """ |
| Adds the given (model) fields to the select set. The field names are |
| added in the order specified. |
| """ |
| alias = self.get_initial_alias() |
| opts = self.get_meta() |
| |
| try: |
| for name in field_names: |
| field, target, u2, joins, u3, u4 = self.setup_joins( |
| name.split(LOOKUP_SEP), opts, alias, False, allow_m2m, |
| True) |
| final_alias = joins[-1] |
| col = target.column |
| if len(joins) > 1: |
| join = self.alias_map[final_alias] |
| if col == join[RHS_JOIN_COL]: |
| self.unref_alias(final_alias) |
| final_alias = join[LHS_ALIAS] |
| col = join[LHS_JOIN_COL] |
| joins = joins[:-1] |
| self.promote_alias_chain(joins[1:]) |
| self.select.append((final_alias, col)) |
| self.select_fields.append(field) |
| except MultiJoin: |
| raise FieldError("Invalid field name: '%s'" % name) |
| except FieldError: |
| names = opts.get_all_field_names() + self.extra.keys() + self.aggregate_select.keys() |
| names.sort() |
| raise FieldError("Cannot resolve keyword %r into field. " |
| "Choices are: %s" % (name, ", ".join(names))) |
| self.remove_inherited_models() |
| |
| def add_ordering(self, *ordering): |
| """ |
| Adds items from the 'ordering' sequence to the query's "order by" |
| clause. These items are either field names (not column names) -- |
| possibly with a direction prefix ('-' or '?') -- or ordinals, |
| corresponding to column positions in the 'select' list. |
| |
| If 'ordering' is empty, all ordering is cleared from the query. |
| """ |
| errors = [] |
| for item in ordering: |
| if not ORDER_PATTERN.match(item): |
| errors.append(item) |
| if errors: |
| raise FieldError('Invalid order_by arguments: %s' % errors) |
| if ordering: |
| self.order_by.extend(ordering) |
| else: |
| self.default_ordering = False |
| |
| def clear_ordering(self, force_empty=False): |
| """ |
| Removes any ordering settings. If 'force_empty' is True, there will be |
| no ordering in the resulting query (not even the model's default). |
| """ |
| self.order_by = [] |
| self.extra_order_by = () |
| if force_empty: |
| self.default_ordering = False |
| |
| def set_group_by(self): |
| """ |
| Expands the GROUP BY clause required by the query. |
| |
| This will usually be the set of all non-aggregate fields in the |
| return data. If the database backend supports grouping by the |
| primary key, and the query would be equivalent, the optimization |
| will be made automatically. |
| """ |
| self.group_by = [] |
| |
| for sel in self.select: |
| self.group_by.append(sel) |
| |
| def add_count_column(self): |
| """ |
| Converts the query to do count(...) or count(distinct(pk)) in order to |
| get its size. |
| """ |
| if not self.distinct: |
| if not self.select: |
| count = self.aggregates_module.Count('*', is_summary=True) |
| else: |
| assert len(self.select) == 1, \ |
| "Cannot add count col with multiple cols in 'select': %r" % self.select |
| count = self.aggregates_module.Count(self.select[0]) |
| else: |
| opts = self.model._meta |
| if not self.select: |
| count = self.aggregates_module.Count((self.join((None, opts.db_table, None, None)), opts.pk.column), |
| is_summary=True, distinct=True) |
| else: |
| # Because of SQL portability issues, multi-column, distinct |
| # counts need a sub-query -- see get_count() for details. |
| assert len(self.select) == 1, \ |
| "Cannot add count col with multiple cols in 'select'." |
| |
| count = self.aggregates_module.Count(self.select[0], distinct=True) |
| # Distinct handling is done in Count(), so don't do it at this |
| # level. |
| self.distinct = False |
| |
| # Set only aggregate to be the count column. |
| # Clear out the select cache to reflect the new unmasked aggregates. |
| self.aggregates = {None: count} |
| self.set_aggregate_mask(None) |
| self.group_by = None |
| |
| def add_select_related(self, fields): |
| """ |
| Sets up the select_related data structure so that we only select |
| certain related models (as opposed to all models, when |
| self.select_related=True). |
| """ |
| field_dict = {} |
| for field in fields: |
| d = field_dict |
| for part in field.split(LOOKUP_SEP): |
| d = d.setdefault(part, {}) |
| self.select_related = field_dict |
| self.related_select_cols = [] |
| self.related_select_fields = [] |
| |
| def add_extra(self, select, select_params, where, params, tables, order_by): |
| """ |
| Adds data to the various extra_* attributes for user-created additions |
| to the query. |
| """ |
| if select: |
| # We need to pair any placeholder markers in the 'select' |
| # dictionary with their parameters in 'select_params' so that |
| # subsequent updates to the select dictionary also adjust the |
| # parameters appropriately. |
| select_pairs = SortedDict() |
| if select_params: |
| param_iter = iter(select_params) |
| else: |
| param_iter = iter([]) |
| for name, entry in select.items(): |
| entry = force_unicode(entry) |
| entry_params = [] |
| pos = entry.find("%s") |
| while pos != -1: |
| entry_params.append(param_iter.next()) |
| pos = entry.find("%s", pos + 2) |
| select_pairs[name] = (entry, entry_params) |
| # This is order preserving, since self.extra_select is a SortedDict. |
| self.extra.update(select_pairs) |
| if where or params: |
| self.where.add(ExtraWhere(where, params), AND) |
| if tables: |
| self.extra_tables += tuple(tables) |
| if order_by: |
| self.extra_order_by = order_by |
| |
| def clear_deferred_loading(self): |
| """ |
| Remove any fields from the deferred loading set. |
| """ |
| self.deferred_loading = (set(), True) |
| |
| def add_deferred_loading(self, field_names): |
| """ |
| Add the given list of model field names to the set of fields to |
| exclude from loading from the database when automatic column selection |
| is done. The new field names are added to any existing field names that |
| are deferred (or removed from any existing field names that are marked |
| as the only ones for immediate loading). |
| """ |
| # Fields on related models are stored in the literal double-underscore |
| # format, so that we can use a set datastructure. We do the foo__bar |
| # splitting and handling when computing the SQL colum names (as part of |
| # get_columns()). |
| existing, defer = self.deferred_loading |
| if defer: |
| # Add to existing deferred names. |
| self.deferred_loading = existing.union(field_names), True |
| else: |
| # Remove names from the set of any existing "immediate load" names. |
| self.deferred_loading = existing.difference(field_names), False |
| |
| def add_immediate_loading(self, field_names): |
| """ |
| Add the given list of model field names to the set of fields to |
| retrieve when the SQL is executed ("immediate loading" fields). The |
| field names replace any existing immediate loading field names. If |
| there are field names already specified for deferred loading, those |
| names are removed from the new field_names before storing the new names |
| for immediate loading. (That is, immediate loading overrides any |
| existing immediate values, but respects existing deferrals.) |
| """ |
| existing, defer = self.deferred_loading |
| if defer: |
| # Remove any existing deferred names from the current set before |
| # setting the new names. |
| self.deferred_loading = set(field_names).difference(existing), False |
| else: |
| # Replace any existing "immediate load" field names. |
| self.deferred_loading = set(field_names), False |
| |
| def get_loaded_field_names(self): |
| """ |
| If any fields are marked to be deferred, returns a dictionary mapping |
| models to a set of names in those fields that will be loaded. If a |
| model is not in the returned dictionary, none of it's fields are |
| deferred. |
| |
| If no fields are marked for deferral, returns an empty dictionary. |
| """ |
| collection = {} |
| self.deferred_to_data(collection, self.get_loaded_field_names_cb) |
| return collection |
| |
| def get_loaded_field_names_cb(self, target, model, fields): |
| """ |
| Callback used by get_deferred_field_names(). |
| """ |
| target[model] = set([f.name for f in fields]) |
| |
| def set_aggregate_mask(self, names): |
| "Set the mask of aggregates that will actually be returned by the SELECT" |
| if names is None: |
| self.aggregate_select_mask = None |
| else: |
| self.aggregate_select_mask = set(names) |
| self._aggregate_select_cache = None |
| |
| def set_extra_mask(self, names): |
| """ |
| Set the mask of extra select items that will be returned by SELECT, |
| we don't actually remove them from the Query since they might be used |
| later |
| """ |
| if names is None: |
| self.extra_select_mask = None |
| else: |
| self.extra_select_mask = set(names) |
| self._extra_select_cache = None |
| |
| def _aggregate_select(self): |
| """The SortedDict of aggregate columns that are not masked, and should |
| be used in the SELECT clause. |
| |
| This result is cached for optimization purposes. |
| """ |
| if self._aggregate_select_cache is not None: |
| return self._aggregate_select_cache |
| elif self.aggregate_select_mask is not None: |
| self._aggregate_select_cache = SortedDict([ |
| (k,v) for k,v in self.aggregates.items() |
| if k in self.aggregate_select_mask |
| ]) |
| return self._aggregate_select_cache |
| else: |
| return self.aggregates |
| aggregate_select = property(_aggregate_select) |
| |
| def _extra_select(self): |
| if self._extra_select_cache is not None: |
| return self._extra_select_cache |
| elif self.extra_select_mask is not None: |
| self._extra_select_cache = SortedDict([ |
| (k,v) for k,v in self.extra.items() |
| if k in self.extra_select_mask |
| ]) |
| return self._extra_select_cache |
| else: |
| return self.extra |
| extra_select = property(_extra_select) |
| |
| def set_start(self, start): |
| """ |
| Sets the table from which to start joining. The start position is |
| specified by the related attribute from the base model. This will |
| automatically set to the select column to be the column linked from the |
| previous table. |
| |
| This method is primarily for internal use and the error checking isn't |
| as friendly as add_filter(). Mostly useful for querying directly |
| against the join table of many-to-many relation in a subquery. |
| """ |
| opts = self.model._meta |
| alias = self.get_initial_alias() |
| field, col, opts, joins, last, extra = self.setup_joins( |
| start.split(LOOKUP_SEP), opts, alias, False) |
| select_col = self.alias_map[joins[1]][LHS_JOIN_COL] |
| select_alias = alias |
| |
| # The call to setup_joins added an extra reference to everything in |
| # joins. Reverse that. |
| for alias in joins: |
| self.unref_alias(alias) |
| |
| # We might be able to trim some joins from the front of this query, |
| # providing that we only traverse "always equal" connections (i.e. rhs |
| # is *always* the same value as lhs). |
| for alias in joins[1:]: |
| join_info = self.alias_map[alias] |
| if (join_info[LHS_JOIN_COL] != select_col |
| or join_info[JOIN_TYPE] != self.INNER): |
| break |
| self.unref_alias(select_alias) |
| select_alias = join_info[RHS_ALIAS] |
| select_col = join_info[RHS_JOIN_COL] |
| self.select = [(select_alias, select_col)] |
| self.remove_inherited_models() |
| |
| |
| def get_order_dir(field, default='ASC'): |
| """ |
| Returns the field name and direction for an order specification. For |
| example, '-foo' is returned as ('foo', 'DESC'). |
| |
| The 'default' param is used to indicate which way no prefix (or a '+' |
| prefix) should sort. The '-' prefix always sorts the opposite way. |
| """ |
| dirn = ORDER_DIR[default] |
| if field[0] == '-': |
| return field[1:], dirn[1] |
| return field, dirn[0] |
| |
| |
| def setup_join_cache(sender, **kwargs): |
| """ |
| The information needed to join between model fields is something that is |
| invariant over the life of the model, so we cache it in the model's Options |
| class, rather than recomputing it all the time. |
| |
| This method initialises the (empty) cache when the model is created. |
| """ |
| sender._meta._join_cache = {} |
| |
| signals.class_prepared.connect(setup_join_cache) |
| |
| def add_to_dict(data, key, value): |
| """ |
| A helper function to add "value" to the set of values for "key", whether or |
| not "key" already exists. |
| """ |
| if key in data: |
| data[key].add(value) |
| else: |
| data[key] = set([value]) |
| |
| def get_proxied_model(opts): |
| int_opts = opts |
| proxied_model = None |
| while int_opts.proxy: |
| proxied_model = int_opts.proxy_for_model |
| int_opts = proxied_model._meta |
| return proxied_model |
