| """ |
| 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 copy 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 connection |
| from django.db.models import signals |
| from django.db.models.fields import FieldDoesNotExist |
| from django.db.models.query_utils import select_related_descend |
| from django.db.models.sql.where import WhereNode, EverythingNode, AND, OR |
| from django.db.models.sql.datastructures import Count |
| from django.core.exceptions import FieldError |
| from datastructures import EmptyResultSet, Empty, MultiJoin |
| from constants import * |
| |
| try: |
| set |
| except NameError: |
| from sets import Set as set # Python 2.3 fallback |
| |
| __all__ = ['Query'] |
| |
| 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 |
| |
| def __init__(self, model, connection, where=WhereNode): |
| self.model = model |
| self.connection = connection |
| 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.start_meta = None |
| self.select_fields = [] |
| self.related_select_fields = [] |
| self.dupe_avoidance = {} |
| self.used_aliases = set() |
| self.filter_is_sticky = False |
| |
| # SQL-related attributes |
| self.select = [] |
| self.tables = [] # Aliases in the order they are created. |
| self.where = where() |
| self.where_class = where |
| self.group_by = [] |
| self.having = [] |
| 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 = [] |
| |
| # 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_select = SortedDict() # Maps col_alias -> (col_sql, params). |
| self.extra_tables = () |
| self.extra_where = () |
| self.extra_params = () |
| self.extra_order_by = () |
| |
| 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.as_sql() |
| return sql % params |
| |
| def __deepcopy__(self, memo): |
| result= self.clone() |
| 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'] = [] |
| del obj_dict['connection'] |
| return obj_dict |
| |
| def __setstate__(self, obj_dict): |
| """ |
| Unpickling support. |
| """ |
| self.__dict__.update(obj_dict) |
| # XXX: Need a better solution for this when multi-db stuff is |
| # supported. It's the only class-reference to the module-level |
| # connection variable. |
| self.connection = connection |
| |
| 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 change. |
| """ |
| if self.start_meta: |
| return self.start_meta |
| return self.model._meta |
| |
| def quote_name_unless_alias(self, name): |
| """ |
| A wrapper around connection.ops.quote_name that doesn't quote aliases |
| for table names. This avoids problems with some SQL dialects that treat |
| quoted strings specially (e.g. PostgreSQL). |
| """ |
| if name in self.quote_cache: |
| return self.quote_cache[name] |
| if ((name in self.alias_map and name not in self.table_map) or |
| name in self.extra_select): |
| self.quote_cache[name] = name |
| return name |
| r = self.connection.ops.quote_name(name) |
| self.quote_cache[name] = r |
| return r |
| |
| def clone(self, klass=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.connection = self.connection |
| 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.ordering_aliases = [] |
| obj.start_meta = self.start_meta |
| 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) |
| obj.where_class = self.where_class |
| obj.group_by = self.group_by[:] |
| obj.having = self.having[:] |
| 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.max_depth = self.max_depth |
| obj.extra_select = self.extra_select.copy() |
| obj.extra_tables = self.extra_tables |
| obj.extra_where = self.extra_where |
| obj.extra_params = self.extra_params |
| obj.extra_order_by = self.extra_order_by |
| 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 results_iter(self): |
| """ |
| Returns an iterator over the results from executing this query. |
| """ |
| resolve_columns = hasattr(self, 'resolve_columns') |
| fields = None |
| for rows in self.execute_sql(MULTI): |
| for row in rows: |
| if resolve_columns: |
| if fields is None: |
| # We only set this up here because |
| # related_select_fields isn't populated until |
| # execute_sql() has been called. |
| if self.select_fields: |
| fields = self.select_fields + self.related_select_fields |
| else: |
| fields = self.model._meta.fields |
| row = self.resolve_columns(row, fields) |
| yield row |
| |
| def get_count(self): |
| """ |
| Performs a COUNT() query using the current filter constraints. |
| """ |
| from subqueries import CountQuery |
| obj = self.clone() |
| obj.clear_ordering(True) |
| obj.clear_limits() |
| obj.select_related = False |
| obj.related_select_cols = [] |
| obj.related_select_fields = [] |
| if len(obj.select) > 1: |
| obj = self.clone(CountQuery, _query=obj, where=self.where_class(), |
| distinct=False) |
| obj.select = [] |
| obj.extra_select = SortedDict() |
| obj.add_count_column() |
| data = obj.execute_sql(SINGLE) |
| if not data: |
| return 0 |
| number = data[0] |
| |
| # 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: |
| number = min(number, self.high_mark - self.low_mark) |
| |
| return number |
| |
| def as_sql(self, with_limits=True, with_col_aliases=False): |
| """ |
| Creates the SQL for this query. Returns the SQL string and list of |
| parameters. |
| |
| If 'with_limits' is False, any limit/offset information is not included |
| in the query. |
| """ |
| self.pre_sql_setup() |
| out_cols = self.get_columns(with_col_aliases) |
| ordering = self.get_ordering() |
| |
| # This must come after 'select' and 'ordering' -- see docstring of |
| # get_from_clause() for details. |
| from_, f_params = self.get_from_clause() |
| |
| where, w_params = self.where.as_sql(qn=self.quote_name_unless_alias) |
| params = [] |
| for val in self.extra_select.itervalues(): |
| params.extend(val[1]) |
| |
| result = ['SELECT'] |
| if self.distinct: |
| result.append('DISTINCT') |
| result.append(', '.join(out_cols + self.ordering_aliases)) |
| |
| result.append('FROM') |
| result.extend(from_) |
| params.extend(f_params) |
| |
| if where: |
| result.append('WHERE %s' % where) |
| params.extend(w_params) |
| if self.extra_where: |
| if not where: |
| result.append('WHERE') |
| else: |
| result.append('AND') |
| result.append(' AND '.join(self.extra_where)) |
| |
| if self.group_by: |
| grouping = self.get_grouping() |
| result.append('GROUP BY %s' % ', '.join(grouping)) |
| |
| if ordering: |
| result.append('ORDER BY %s' % ', '.join(ordering)) |
| |
| if with_limits: |
| if self.high_mark is not None: |
| result.append('LIMIT %d' % (self.high_mark - self.low_mark)) |
| if self.low_mark: |
| if self.high_mark is None: |
| val = self.connection.ops.no_limit_value() |
| if val: |
| result.append('LIMIT %d' % val) |
| result.append('OFFSET %d' % self.low_mark) |
| |
| params.extend(self.extra_params) |
| return ' '.join(result), tuple(params) |
| |
| 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." |
| |
| # 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_select and rhs.extra_select: |
| raise ValueError("When merging querysets using 'or', you " |
| "cannot have extra(select=...) on both sides.") |
| if self.extra_where and rhs.extra_where: |
| raise ValueError("When merging querysets using 'or', you " |
| "cannot have extra(where=...) on both sides.") |
| self.extra_select.update(rhs.extra_select) |
| self.extra_tables += rhs.extra_tables |
| self.extra_where += rhs.extra_where |
| self.extra_params += rhs.extra_params |
| |
| # 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 pre_sql_setup(self): |
| """ |
| Does any necessary class setup immediately prior to producing SQL. This |
| is for things that can't necessarily be done in __init__ because we |
| might not have all the pieces in place at that time. |
| """ |
| if not self.tables: |
| self.join((None, self.model._meta.db_table, None, None)) |
| if self.select_related and not self.related_select_cols: |
| self.fill_related_selections() |
| |
| def get_columns(self, with_aliases=False): |
| """ |
| Return the list of columns to use in the select statement. If no |
| columns have been specified, returns all columns relating to fields in |
| the model. |
| |
| If 'with_aliases' is true, any column names that are duplicated |
| (without the table names) are given unique aliases. This is needed in |
| some cases to avoid ambiguitity with nested queries. |
| """ |
| qn = self.quote_name_unless_alias |
| qn2 = self.connection.ops.quote_name |
| result = ['(%s) AS %s' % (col[0], qn2(alias)) for alias, col in self.extra_select.iteritems()] |
| aliases = set(self.extra_select.keys()) |
| if with_aliases: |
| col_aliases = aliases.copy() |
| else: |
| col_aliases = set() |
| if self.select: |
| for col in self.select: |
| if isinstance(col, (list, tuple)): |
| r = '%s.%s' % (qn(col[0]), qn(col[1])) |
| if with_aliases and col[1] in col_aliases: |
| c_alias = 'Col%d' % len(col_aliases) |
| result.append('%s AS %s' % (r, c_alias)) |
| aliases.add(c_alias) |
| col_aliases.add(c_alias) |
| else: |
| result.append(r) |
| aliases.add(r) |
| col_aliases.add(col[1]) |
| else: |
| result.append(col.as_sql(quote_func=qn)) |
| if hasattr(col, 'alias'): |
| aliases.add(col.alias) |
| col_aliases.add(col.alias) |
| elif self.default_cols: |
| cols, new_aliases = self.get_default_columns(with_aliases, |
| col_aliases) |
| result.extend(cols) |
| aliases.update(new_aliases) |
| for table, col in self.related_select_cols: |
| r = '%s.%s' % (qn(table), qn(col)) |
| if with_aliases and col in col_aliases: |
| c_alias = 'Col%d' % len(col_aliases) |
| result.append('%s AS %s' % (r, c_alias)) |
| aliases.add(c_alias) |
| col_aliases.add(c_alias) |
| else: |
| result.append(r) |
| aliases.add(r) |
| col_aliases.add(col) |
| |
| self._select_aliases = aliases |
| return result |
| |
| def get_default_columns(self, with_aliases=False, col_aliases=None, |
| start_alias=None, opts=None, as_pairs=False): |
| """ |
| Computes the default columns for selecting every field in the base |
| model. |
| |
| Returns a list of strings, quoted appropriately for use in SQL |
| directly, as well as a set of aliases used in the select statement (if |
| 'as_pairs' is True, returns a list of (alias, col_name) pairs instead |
| of strings as the first component and None as the second component). |
| """ |
| result = [] |
| if opts is None: |
| opts = self.model._meta |
| if start_alias: |
| table_alias = start_alias |
| else: |
| table_alias = self.tables[0] |
| root_pk = opts.pk.column |
| seen = {None: table_alias} |
| qn = self.quote_name_unless_alias |
| qn2 = self.connection.ops.quote_name |
| aliases = set() |
| for field, model in opts.get_fields_with_model(): |
| try: |
| alias = seen[model] |
| except KeyError: |
| alias = self.join((table_alias, model._meta.db_table, |
| root_pk, model._meta.pk.column)) |
| seen[model] = alias |
| if as_pairs: |
| result.append((alias, field.column)) |
| continue |
| if with_aliases and field.column in col_aliases: |
| c_alias = 'Col%d' % len(col_aliases) |
| result.append('%s.%s AS %s' % (qn(alias), |
| qn2(field.column), c_alias)) |
| col_aliases.add(c_alias) |
| aliases.add(c_alias) |
| else: |
| r = '%s.%s' % (qn(alias), qn2(field.column)) |
| result.append(r) |
| aliases.add(r) |
| if with_aliases: |
| col_aliases.add(field.column) |
| if as_pairs: |
| return result, None |
| return result, aliases |
| |
| def get_from_clause(self): |
| """ |
| Returns a list of strings that are joined together to go after the |
| "FROM" part of the query, as well as a list any extra parameters that |
| need to be included. Sub-classes, can override this to create a |
| from-clause via a "select", for example (e.g. CountQuery). |
| |
| This should only be called after any SQL construction methods that |
| might change the tables we need. This means the select columns and |
| ordering must be done first. |
| """ |
| result = [] |
| qn = self.quote_name_unless_alias |
| qn2 = self.connection.ops.quote_name |
| first = True |
| for alias in self.tables: |
| if not self.alias_refcount[alias]: |
| continue |
| try: |
| name, alias, join_type, lhs, lhs_col, col, nullable = self.alias_map[alias] |
| except KeyError: |
| # Extra tables can end up in self.tables, but not in the |
| # alias_map if they aren't in a join. That's OK. We skip them. |
| continue |
| alias_str = (alias != name and ' %s' % alias or '') |
| if join_type and not first: |
| result.append('%s %s%s ON (%s.%s = %s.%s)' |
| % (join_type, qn(name), alias_str, qn(lhs), |
| qn2(lhs_col), qn(alias), qn2(col))) |
| else: |
| connector = not first and ', ' or '' |
| result.append('%s%s%s' % (connector, qn(name), alias_str)) |
| first = False |
| for t in self.extra_tables: |
| alias, unused = self.table_alias(t) |
| # Only add the alias if it's not already present (the table_alias() |
| # calls increments the refcount, so an alias refcount of one means |
| # this is the only reference. |
| if alias not in self.alias_map or self.alias_refcount[alias] == 1: |
| connector = not first and ', ' or '' |
| result.append('%s%s' % (connector, qn(alias))) |
| first = False |
| return result, [] |
| |
| def get_grouping(self): |
| """ |
| Returns a tuple representing the SQL elements in the "group by" clause. |
| """ |
| qn = self.quote_name_unless_alias |
| result = [] |
| for col in self.group_by: |
| if isinstance(col, (list, tuple)): |
| result.append('%s.%s' % (qn(col[0]), qn(col[1]))) |
| elif hasattr(col, 'as_sql'): |
| result.append(col.as_sql(qn)) |
| else: |
| result.append(str(col)) |
| return result |
| |
| def get_ordering(self): |
| """ |
| Returns list representing the SQL elements in the "order by" clause. |
| Also sets the ordering_aliases attribute on this instance to a list of |
| extra aliases needed in the select. |
| |
| Determining the ordering SQL can change the tables we need to include, |
| so this should be run *before* get_from_clause(). |
| """ |
| if self.extra_order_by: |
| ordering = self.extra_order_by |
| elif not self.default_ordering: |
| ordering = [] |
| else: |
| ordering = self.order_by or self.model._meta.ordering |
| qn = self.quote_name_unless_alias |
| qn2 = self.connection.ops.quote_name |
| distinct = self.distinct |
| select_aliases = self._select_aliases |
| result = [] |
| ordering_aliases = [] |
| if self.standard_ordering: |
| asc, desc = ORDER_DIR['ASC'] |
| else: |
| asc, desc = ORDER_DIR['DESC'] |
| for field in ordering: |
| if field == '?': |
| result.append(self.connection.ops.random_function_sql()) |
| continue |
| if isinstance(field, int): |
| if field < 0: |
| order = desc |
| field = -field |
| else: |
| order = asc |
| result.append('%s %s' % (field, order)) |
| continue |
| if '.' in field: |
| # This came in through an extra(order_by=...) addition. Pass it |
| # on verbatim. |
| col, order = get_order_dir(field, asc) |
| table, col = col.split('.', 1) |
| elt = '%s.%s' % (qn(table), col) |
| if not distinct or elt in select_aliases: |
| result.append('%s %s' % (elt, order)) |
| elif get_order_dir(field)[0] not in self.extra_select: |
| # 'col' is of the form 'field' or 'field1__field2' or |
| # '-field1__field2__field', etc. |
| for table, col, order in self.find_ordering_name(field, |
| self.model._meta, default_order=asc): |
| elt = '%s.%s' % (qn(table), qn2(col)) |
| if distinct and elt not in select_aliases: |
| ordering_aliases.append(elt) |
| result.append('%s %s' % (elt, order)) |
| else: |
| col, order = get_order_dir(field, asc) |
| elt = qn(col) |
| if distinct and elt not in select_aliases: |
| ordering_aliases.append(elt) |
| result.append('%s %s' % (elt, order)) |
| self.ordering_aliases = ordering_aliases |
| return result |
| |
| def find_ordering_name(self, name, opts, alias=None, default_order='ASC', |
| already_seen=None): |
| """ |
| Returns the table alias (the name might be ambiguous, the alias will |
| not be) and column name for ordering by the given 'name' parameter. |
| The 'name' is of the form 'field1__field2__...__fieldN'. |
| """ |
| name, order = get_order_dir(name, default_order) |
| pieces = name.split(LOOKUP_SEP) |
| if not alias: |
| alias = self.get_initial_alias() |
| field, target, opts, joins, last = self.setup_joins(pieces, opts, |
| alias, False) |
| alias = joins[-1] |
| col = target.column |
| if not field.rel: |
| # To avoid inadvertent trimming of a necessary alias, use the |
| # refcount to show that we are referencing a non-relation field on |
| # the model. |
| self.ref_alias(alias) |
| |
| # Must use left outer joins for nullable fields. |
| for join in joins: |
| self.promote_alias(join) |
| |
| # If we get to this point and the field is a relation to another model, |
| # append the default ordering for that model. |
| if field.rel and len(joins) > 1 and opts.ordering: |
| # Firstly, avoid infinite loops. |
| if not already_seen: |
| already_seen = set() |
| join_tuple = tuple([self.alias_map[j][TABLE_NAME] for j in joins]) |
| if join_tuple in already_seen: |
| raise FieldError('Infinite loop caused by ordering.') |
| already_seen.add(join_tuple) |
| |
| results = [] |
| for item in opts.ordering: |
| results.extend(self.find_ordering_name(item, opts, alias, |
| order, already_seen)) |
| return results |
| |
| if alias: |
| # We have to do the same "final join" optimisation as in |
| # add_filter, since the final column might not otherwise be part of |
| # the select set (so we can't order on it). |
| while 1: |
| join = self.alias_map[alias] |
| if col != join[RHS_JOIN_COL]: |
| break |
| self.unref_alias(alias) |
| alias = join[LHS_ALIAS] |
| col = join[LHS_JOIN_COL] |
| return [(alias, col, order)] |
| |
| 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.alias_map[alias] = None |
| 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] != self.LOUTER): |
| data = list(self.alias_map[alias]) |
| data[JOIN_TYPE] = self.LOUTER |
| self.alias_map[alias] = tuple(data) |
| return True |
| return False |
| |
| 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" and "where". |
| self.where.relabel_aliases(change_map) |
| for pos, col in enumerate(self.select): |
| if isinstance(col, (list, tuple)): |
| self.select[pos] = (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 |
| |
| # 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. |
| """ |
| assert ord(self.alias_prefix) < ord('Z') |
| self.alias_prefix = chr(ord(self.alias_prefix) + 1) |
| change_map = {} |
| prefix = self.alias_prefix |
| 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. Otherwise |
| 'reuse' must be a set and a new join is created unless one of the |
| aliases in `reuse` can be used. |
| |
| 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 |
| 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 fill_related_selections(self, opts=None, root_alias=None, cur_depth=1, |
| used=None, requested=None, restricted=None, nullable=None, |
| dupe_set=None): |
| """ |
| Fill in the information needed for a select_related query. The current |
| depth is measured as the number of connections away from the root model |
| (for example, cur_depth=1 means we are looking at models with direct |
| connections to the root model). |
| """ |
| if not restricted and self.max_depth and cur_depth > self.max_depth: |
| # We've recursed far enough; bail out. |
| return |
| |
| if not opts: |
| opts = self.get_meta() |
| root_alias = self.get_initial_alias() |
| self.related_select_cols = [] |
| self.related_select_fields = [] |
| if not used: |
| used = set() |
| if dupe_set is None: |
| dupe_set = set() |
| orig_dupe_set = dupe_set |
| orig_used = used |
| |
| # Setup for the case when only particular related fields should be |
| # included in the related selection. |
| if requested is None and restricted is not False: |
| if isinstance(self.select_related, dict): |
| requested = self.select_related |
| restricted = True |
| else: |
| restricted = False |
| |
| for f, model in opts.get_fields_with_model(): |
| if not select_related_descend(f, restricted, requested): |
| continue |
| dupe_set = orig_dupe_set.copy() |
| used = orig_used.copy() |
| table = f.rel.to._meta.db_table |
| if nullable or f.null: |
| promote = True |
| else: |
| promote = False |
| if model: |
| int_opts = opts |
| alias = root_alias |
| for int_model in opts.get_base_chain(model): |
| lhs_col = int_opts.parents[int_model].column |
| dedupe = lhs_col in opts.duplicate_targets |
| if dedupe: |
| used.update(self.dupe_avoidance.get(id(opts), lhs_col), |
| ()) |
| dupe_set.add((opts, lhs_col)) |
| int_opts = int_model._meta |
| alias = self.join((alias, int_opts.db_table, lhs_col, |
| int_opts.pk.column), exclusions=used, |
| promote=promote) |
| for (dupe_opts, dupe_col) in dupe_set: |
| self.update_dupe_avoidance(dupe_opts, dupe_col, alias) |
| else: |
| alias = root_alias |
| |
| dedupe = f.column in opts.duplicate_targets |
| if dupe_set or dedupe: |
| used.update(self.dupe_avoidance.get((id(opts), f.column), ())) |
| if dedupe: |
| dupe_set.add((opts, f.column)) |
| |
| alias = self.join((alias, table, f.column, |
| f.rel.get_related_field().column), exclusions=used, |
| promote=promote) |
| used.add(alias) |
| self.related_select_cols.extend(self.get_default_columns( |
| start_alias=alias, opts=f.rel.to._meta, as_pairs=True)[0]) |
| self.related_select_fields.extend(f.rel.to._meta.fields) |
| if restricted: |
| next = requested.get(f.name, {}) |
| else: |
| next = False |
| if f.null is not None: |
| new_nullable = f.null |
| else: |
| new_nullable = None |
| for dupe_opts, dupe_col in dupe_set: |
| self.update_dupe_avoidance(dupe_opts, dupe_col, alias) |
| self.fill_related_selections(f.rel.to._meta, alias, cur_depth + 1, |
| used, next, restricted, new_nullable, dupe_set) |
| |
| def add_filter(self, filter_expr, connector=AND, negate=False, trim=False, |
| can_reuse=None): |
| """ |
| 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. |
| """ |
| 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() |
| |
| # 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() |
| |
| opts = self.get_meta() |
| alias = self.get_initial_alias() |
| allow_many = trim or not negate |
| |
| try: |
| field, target, opts, join_list, last = self.setup_joins(parts, opts, |
| alias, True, allow_many, can_reuse=can_reuse) |
| except MultiJoin, e: |
| self.split_exclude(filter_expr, LOOKUP_SEP.join(parts[:e.level])) |
| return |
| 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: |
| # An optimization: if the final join is against the same column as |
| # we are comparing against, we can go back one step in the join |
| # chain and compare against the lhs of the join instead (and then |
| # repeat the optimization). The result, potentially, involves less |
| # table joins. |
| join = self.alias_map[alias] |
| if col != join[RHS_JOIN_COL]: |
| 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() |
| |
| if (lookup_type == 'isnull' and value is True and not negate and |
| final > 1): |
| # If the comparison is against NULL, we need to use a left outer |
| # join when connecting to the previous model. We make that |
| # adjustment here. We don't do this unless needed as it's less |
| # efficient at the database level. |
| self.promote_alias(join_list[penultimate]) |
| |
| 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 |
| 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 |
| for join in join_it: |
| if self.promote_alias(join, join_promote): |
| join_promote = True |
| for table in table_it: |
| # Some of these will have been promoted from the join_list, but |
| # that's harmless. |
| if self.promote_alias(table, table_promote): |
| table_promote = True |
| |
| self.where.add((alias, col, field, lookup_type, value), connector) |
| |
| if negate: |
| for alias in join_list: |
| self.promote_alias(alias) |
| if lookup_type != 'isnull': |
| if final > 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((alias, j_col, None, 'isnull', True), AND) |
| entry.negate() |
| self.where.add(entry, AND) |
| break |
| elif not (lookup_type == 'in' 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. |
| entry = self.where_class() |
| entry.add((alias, col, None, 'isnull', True), AND) |
| entry.negate() |
| self.where.add(entry, AND) |
| |
| if can_reuse is not None: |
| can_reuse.update(join_list) |
| |
| 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 isinstance(child, Node): |
| self.where.start_subtree(connector) |
| self.add_q(child, used_aliases) |
| self.where.end_subtree() |
| else: |
| self.add_filter(child, connector, q_object.negated, |
| can_reuse=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): |
| """ |
| 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). |
| |
| 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() |
| 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() |
| 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. |
| for int_model in opts.get_base_chain(model): |
| 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 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) |
| 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: |
| raise FieldError("Join on field %r not permitted." % name) |
| |
| return field, target, opts, joins, last |
| |
| 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): |
| """ |
| 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, self.connection) |
| query.add_filter(filter_expr) |
| query.set_start(prefix) |
| query.clear_ordering(True) |
| self.add_filter(('%s__in' % prefix, query), negate=True, trim=True) |
| |
| 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: |
| 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: |
| 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 or self.high_mark) |
| |
| 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 = 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] |
| promote = False |
| for join in joins[1:]: |
| # Only nullable aliases are promoted, so we don't end up |
| # doing unnecessary left outer joins here. |
| if self.promote_alias(join, promote): |
| promote = True |
| 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_select.keys() |
| names.sort() |
| raise FieldError("Cannot resolve keyword %r into field. " |
| "Choices are: %s" % (name, ", ".join(names))) |
| |
| 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 add_count_column(self): |
| """ |
| Converts the query to do count(...) or count(distinct(pk)) in order to |
| get its size. |
| """ |
| # TODO: When group_by support is added, this needs to be adjusted so |
| # that it doesn't totally overwrite the select list. |
| if not self.distinct: |
| if not self.select: |
| select = Count() |
| else: |
| assert len(self.select) == 1, \ |
| "Cannot add count col with multiple cols in 'select': %r" % self.select |
| select = Count(self.select[0]) |
| else: |
| opts = self.model._meta |
| if not self.select: |
| select = Count((self.join((None, opts.db_table, None, None)), |
| opts.pk.column), 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'." |
| select = Count(self.select[0], True) |
| |
| # Distinct handling is done in Count(), so don't do it at this |
| # level. |
| self.distinct = False |
| self.select = [select] |
| self.select_fields = [None] |
| self.extra_select = {} |
| |
| 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_select.update(select_pairs) |
| if where: |
| self.extra_where += tuple(where) |
| if params: |
| self.extra_params += tuple(params) |
| if tables: |
| self.extra_tables += tuple(tables) |
| if order_by: |
| self.extra_order_by = order_by |
| |
| def trim_extra_select(self, names): |
| """ |
| Removes any aliases in the extra_select dictionary that aren't in |
| 'names'. |
| |
| This is needed if we are selecting certain values that don't incldue |
| all of the extra_select names. |
| """ |
| for key in set(self.extra_select).difference(set(names)): |
| del self.extra_select[key] |
| |
| 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 = self.setup_joins( |
| start.split(LOOKUP_SEP), opts, alias, False) |
| alias = joins[last[-1]] |
| self.select = [(alias, self.alias_map[alias][RHS_JOIN_COL])] |
| self.select_fields = [field] |
| self.start_meta = opts |
| |
| # The call to setup_joins add an extra reference to everything in |
| # joins. So we need to unref everything once, and everything prior to |
| # the final join a second time. |
| for alias in joins: |
| self.unref_alias(alias) |
| for alias in joins[:last[-1]]: |
| self.unref_alias(alias) |
| |
| def execute_sql(self, result_type=MULTI): |
| """ |
| Run the query against the database and returns the result(s). The |
| return value is a single data item if result_type is SINGLE, or an |
| iterator over the results if the result_type is MULTI. |
| |
| result_type is either MULTI (use fetchmany() to retrieve all rows), |
| SINGLE (only retrieve a single row), or None (no results expected, but |
| the cursor is returned, since it's used by subclasses such as |
| InsertQuery). |
| """ |
| try: |
| sql, params = self.as_sql() |
| if not sql: |
| raise EmptyResultSet |
| except EmptyResultSet: |
| if result_type == MULTI: |
| return empty_iter() |
| else: |
| return |
| |
| cursor = self.connection.cursor() |
| cursor.execute(sql, params) |
| |
| if not result_type: |
| return cursor |
| if result_type == SINGLE: |
| if self.ordering_aliases: |
| return cursor.fetchone()[:-len(results.ordering_aliases)] |
| return cursor.fetchone() |
| |
| # The MULTI case. |
| if self.ordering_aliases: |
| result = order_modified_iter(cursor, len(self.ordering_aliases), |
| self.connection.features.empty_fetchmany_value) |
| else: |
| result = iter((lambda: cursor.fetchmany(GET_ITERATOR_CHUNK_SIZE)), |
| self.connection.features.empty_fetchmany_value) |
| if not self.connection.features.can_use_chunked_reads: |
| # If we are using non-chunked reads, we return the same data |
| # structure as normally, but ensure it is all read into memory |
| # before going any further. |
| return list(result) |
| return result |
| |
| # Use the backend's custom Query class if it defines one. Otherwise, use the |
| # default. |
| if connection.features.uses_custom_query_class: |
| Query = connection.ops.query_class(Query) |
| |
| 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 empty_iter(): |
| """ |
| Returns an iterator containing no results. |
| """ |
| yield iter([]).next() |
| |
| def order_modified_iter(cursor, trim, sentinel): |
| """ |
| Yields blocks of rows from a cursor. We use this iterator in the special |
| case when extra output columns have been added to support ordering |
| requirements. We must trim those extra columns before anything else can use |
| the results, since they're only needed to make the SQL valid. |
| """ |
| for rows in iter((lambda: cursor.fetchmany(GET_ITERATOR_CHUNK_SIZE)), |
| sentinel): |
| yield [r[:-trim] for r in rows] |
| |
| 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) |
| |
