from itertools import izip from django.core.exceptions import FieldError from django.db import transaction from django.db.backends.util import truncate_name from django.db.models.query_utils import select_related_descend from django.db.models.sql.constants import * from django.db.models.sql.datastructures import EmptyResultSet from django.db.models.sql.expressions import SQLEvaluator from django.db.models.sql.query import get_order_dir, Query from django.db.utils import DatabaseError class SQLCompiler(object): def __init__(self, query, connection, using): self.query = query self.connection = connection self.using = using self.quote_cache = {} 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. # TODO: after the query has been executed, the altered state should be # cleaned. We are not using a clone() of the query here. """ if not self.query.tables: self.query.join((None, self.query.model._meta.db_table, None, None)) if (not self.query.select and self.query.default_cols and not self.query.included_inherited_models): self.query.setup_inherited_models() if self.query.select_related and not self.query.related_select_cols: self.fill_related_selections() 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.query.alias_map and name not in self.query.table_map) or name in self.query.extra_select): self.quote_cache[name] = name return name r = self.connection.ops.quote_name(name) self.quote_cache[name] = r return r 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. """ if with_limits and self.query.low_mark == self.query.high_mark: return '', () self.pre_sql_setup() # After executing the query, we must get rid of any joins the query # setup created. So, take note of alias counts before the query ran. # However we do not want to get rid of stuff done in pre_sql_setup(), # as the pre_sql_setup will modify query state in a way that forbids # another run of it. self.refcounts_before = self.query.alias_refcount.copy() out_cols = self.get_columns(with_col_aliases) ordering, ordering_group_by = self.get_ordering() distinct_fields = self.get_distinct() # This must come after 'select', 'ordering' and 'distinct' -- see # docstring of get_from_clause() for details. from_, f_params = self.get_from_clause() qn = self.quote_name_unless_alias where, w_params = self.query.where.as_sql(qn=qn, connection=self.connection) having, h_params = self.query.having.as_sql(qn=qn, connection=self.connection) params = [] for val in self.query.extra_select.itervalues(): params.extend(val[1]) result = ['SELECT'] if self.query.distinct: result.append(self.connection.ops.distinct_sql(distinct_fields)) result.append(', '.join(out_cols + self.query.ordering_aliases)) result.append('FROM') result.extend(from_) params.extend(f_params) if where: result.append('WHERE %s' % where) params.extend(w_params) grouping, gb_params = self.get_grouping() if grouping: if distinct_fields: raise NotImplementedError( "annotate() + distinct(fields) not implemented.") if ordering: # If the backend can't group by PK (i.e., any database # other than MySQL), then any fields mentioned in the # ordering clause needs to be in the group by clause. if not self.connection.features.allows_group_by_pk: for col, col_params in ordering_group_by: if col not in grouping: grouping.append(str(col)) gb_params.extend(col_params) else: ordering = self.connection.ops.force_no_ordering() result.append('GROUP BY %s' % ', '.join(grouping)) params.extend(gb_params) if having: result.append('HAVING %s' % having) params.extend(h_params) if ordering: result.append('ORDER BY %s' % ', '.join(ordering)) if with_limits: if self.query.high_mark is not None: result.append('LIMIT %d' % (self.query.high_mark - self.query.low_mark)) if self.query.low_mark: if self.query.high_mark is None: val = self.connection.ops.no_limit_value() if val: result.append('LIMIT %d' % val) result.append('OFFSET %d' % self.query.low_mark) if self.query.select_for_update and self.connection.features.has_select_for_update: # If we've been asked for a NOWAIT query but the backend does not support it, # raise a DatabaseError otherwise we could get an unexpected deadlock. nowait = self.query.select_for_update_nowait if nowait and not self.connection.features.has_select_for_update_nowait: raise DatabaseError('NOWAIT is not supported on this database backend.') result.append(self.connection.ops.for_update_sql(nowait=nowait)) # Finally do cleanup - get rid of the joins we created above. self.query.reset_refcounts(self.refcounts_before) return ' '.join(result), tuple(params) def as_nested_sql(self): """ Perform the same functionality as the as_sql() method, returning an SQL string and parameters. However, the alias prefixes are bumped beforehand (in a copy -- the current query isn't changed), and any ordering is removed if the query is unsliced. Used when nesting this query inside another. """ obj = self.query.clone() if obj.low_mark == 0 and obj.high_mark is None: # If there is no slicing in use, then we can safely drop all ordering obj.clear_ordering(True) obj.bump_prefix() return obj.get_compiler(connection=self.connection).as_sql() def get_columns(self, with_aliases=False): """ Returns 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 ambiguity 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.query.extra_select.iteritems()] aliases = set(self.query.extra_select.keys()) if with_aliases: col_aliases = aliases.copy() else: col_aliases = set() if self.query.select: only_load = self.deferred_to_columns() for col in self.query.select: if isinstance(col, (list, tuple)): alias, column = col table = self.query.alias_map[alias][TABLE_NAME] if table in only_load and column not in only_load[table]: continue r = '%s.%s' % (qn(alias), qn(column)) if with_aliases: if 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('%s AS %s' % (r, qn2(col[1]))) aliases.add(r) col_aliases.add(col[1]) else: result.append(r) aliases.add(r) col_aliases.add(col[1]) else: result.append(col.as_sql(qn, self.connection)) if hasattr(col, 'alias'): aliases.add(col.alias) col_aliases.add(col.alias) elif self.query.default_cols: cols, new_aliases = self.get_default_columns(with_aliases, col_aliases) result.extend(cols) aliases.update(new_aliases) max_name_length = self.connection.ops.max_name_length() result.extend([ '%s%s' % ( aggregate.as_sql(qn, self.connection), alias is not None and ' AS %s' % qn(truncate_name(alias, max_name_length)) or '' ) for alias, aggregate in self.query.aggregate_select.items() ]) for table, col in self.query.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, local_only=False): """ Computes the default columns for selecting every field in the base model. Will sometimes be called to pull in related models (e.g. via select_related), in which case "opts" and "start_alias" will be given to provide a starting point for the traversal. 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.query.model._meta qn = self.quote_name_unless_alias qn2 = self.connection.ops.quote_name aliases = set() only_load = self.deferred_to_columns() # Skip all proxy to the root proxied model proxied_model = opts.concrete_model if start_alias: seen = {None: start_alias} for field, model in opts.get_fields_with_model(): if local_only and model is not None: continue if start_alias: try: alias = seen[model] except KeyError: if model is proxied_model: alias = start_alias else: link_field = opts.get_ancestor_link(model) alias = self.query.join((start_alias, model._meta.db_table, link_field.column, model._meta.pk.column)) seen[model] = alias else: # If we're starting from the base model of the queryset, the # aliases will have already been set up in pre_sql_setup(), so # we can save time here. alias = self.query.included_inherited_models[model] table = self.query.alias_map[alias][TABLE_NAME] if table in only_load and field.column not in only_load[table]: continue if as_pairs: result.append((alias, field.column)) aliases.add(alias) 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) return result, aliases def get_distinct(self): """ Returns a quoted list of fields to use in DISTINCT ON part of the query. Note that this method can alter the tables in the query, and thus it must be called before get_from_clause(). """ qn = self.quote_name_unless_alias qn2 = self.connection.ops.quote_name result = [] opts = self.query.model._meta for name in self.query.distinct_fields: parts = name.split(LOOKUP_SEP) field, col, alias, _, _ = self._setup_joins(parts, opts, None) col, alias = self._final_join_removal(col, alias) result.append("%s.%s" % (qn(alias), qn2(col))) return result def get_ordering(self): """ Returns a tuple containing a list representing the SQL elements in the "order by" clause, and the list of SQL elements that need to be added to the GROUP BY clause as a result of the ordering. 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.query.extra_order_by: ordering = self.query.extra_order_by elif not self.query.default_ordering: ordering = self.query.order_by else: ordering = (self.query.order_by or self.query.model._meta.ordering or []) qn = self.quote_name_unless_alias qn2 = self.connection.ops.quote_name distinct = self.query.distinct select_aliases = self._select_aliases result = [] group_by = [] ordering_aliases = [] if self.query.standard_ordering: asc, desc = ORDER_DIR['ASC'] else: asc, desc = ORDER_DIR['DESC'] # It's possible, due to model inheritance, that normal usage might try # to include the same field more than once in the ordering. We track # the table/column pairs we use and discard any after the first use. processed_pairs = set() 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)) group_by.append((field, [])) continue col, order = get_order_dir(field, asc) if col in self.query.aggregate_select: result.append('%s %s' % (qn(col), order)) continue if '.' in field: # This came in through an extra(order_by=...) addition. Pass it # on verbatim. table, col = col.split('.', 1) if (table, col) not in processed_pairs: elt = '%s.%s' % (qn(table), col) processed_pairs.add((table, col)) if not distinct or elt in select_aliases: result.append('%s %s' % (elt, order)) group_by.append((elt, [])) elif get_order_dir(field)[0] not in self.query.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.query.model._meta, default_order=asc): if (table, col) not in processed_pairs: elt = '%s.%s' % (qn(table), qn2(col)) processed_pairs.add((table, col)) if distinct and elt not in select_aliases: ordering_aliases.append(elt) result.append('%s %s' % (elt, order)) group_by.append((elt, [])) else: elt = qn2(col) if distinct and col not in select_aliases: ordering_aliases.append(elt) result.append('%s %s' % (elt, order)) group_by.append(self.query.extra_select[col]) self.query.ordering_aliases = ordering_aliases return result, group_by 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) field, col, alias, joins, opts = self._setup_joins(pieces, opts, alias) # 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.query.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 col, alias = self._final_join_removal(col, alias) return [(alias, col, order)] def _setup_joins(self, pieces, opts, alias): """ A helper method for get_ordering and get_distinct. This method will call query.setup_joins, handle refcounts and then promote the joins. Note that get_ordering and get_distinct must produce same target columns on same input, as the prefixes of get_ordering and get_distinct must match. Executing SQL where this is not true is an error. """ if not alias: alias = self.query.get_initial_alias() field, target, opts, joins, _, _ = self.query.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.query.ref_alias(alias) # Must use left outer joins for nullable fields and their relations. # Ordering or distinct must not affect the returned set, and INNER # JOINS for nullable fields could do this. self.query.promote_alias_chain(joins, self.query.alias_map[joins[0]][JOIN_TYPE] == self.query.LOUTER) return field, col, alias, joins, opts def _final_join_removal(self, col, alias): """ A helper method for get_distinct and get_ordering. This method will trim extra not-needed joins from the tail of the join chain. This is very similar to what is done in trim_joins, but we will trim LEFT JOINS here. It would be a good idea to consolidate this method and query.trim_joins(). """ if alias: while 1: join = self.query.alias_map[alias] if col != join[RHS_JOIN_COL]: break self.query.unref_alias(alias) alias = join[LHS_ALIAS] col = join[LHS_JOIN_COL] return col, alias 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". This should only be called after any SQL construction methods that might change the tables we need. This means the select columns, ordering and distinct must be done first. """ result = [] qn = self.quote_name_unless_alias qn2 = self.connection.ops.quote_name first = True for alias in self.query.tables: if not self.query.alias_refcount[alias]: continue try: name, alias, join_type, lhs, lhs_col, col, nullable = self.query.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.query.extra_tables: alias, unused = self.query.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.query.alias_map or self.query.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, params = [], [] if self.query.group_by is not None: if (len(self.query.model._meta.fields) == len(self.query.select) and self.connection.features.allows_group_by_pk): self.query.group_by = [ (self.query.model._meta.db_table, self.query.model._meta.pk.column) ] group_by = self.query.group_by or [] extra_selects = [] for extra_select, extra_params in self.query.extra_select.itervalues(): extra_selects.append(extra_select) params.extend(extra_params) cols = (group_by + self.query.select + self.query.related_select_cols + extra_selects) seen = set() for col in cols: if col in seen: continue seen.add(col) 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, self.connection)) else: result.append('(%s)' % str(col)) return result, params def fill_related_selections(self, opts=None, root_alias=None, cur_depth=1, used=None, requested=None, restricted=None, nullable=None, dupe_set=None, avoid_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.query.max_depth and cur_depth > self.query.max_depth: # We've recursed far enough; bail out. return if not opts: opts = self.query.get_meta() root_alias = self.query.get_initial_alias() self.query.related_select_cols = [] self.query.related_select_fields = [] if not used: used = set() if dupe_set is None: dupe_set = set() if avoid_set is None: avoid_set = set() orig_dupe_set = dupe_set # Setup for the case when only particular related fields should be # included in the related selection. if requested is None: if isinstance(self.query.select_related, dict): requested = self.query.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 # The "avoid" set is aliases we want to avoid just for this # particular branch of the recursion. They aren't permanently # forbidden from reuse in the related selection tables (which is # what "used" specifies). avoid = avoid_set.copy() dupe_set = orig_dupe_set.copy() table = f.rel.to._meta.db_table promote = nullable or f.null if model: int_opts = opts alias = root_alias alias_chain = [] for int_model in opts.get_base_chain(model): # Proxy model have elements in base chain # with no parents, assign the new options # object and skip to the next base in that # case if not int_opts.parents[int_model]: int_opts = int_model._meta continue lhs_col = int_opts.parents[int_model].column dedupe = lhs_col in opts.duplicate_targets if dedupe: avoid.update(self.query.dupe_avoidance.get((id(opts), lhs_col), ())) dupe_set.add((opts, lhs_col)) int_opts = int_model._meta alias = self.query.join((alias, int_opts.db_table, lhs_col, int_opts.pk.column), exclusions=used, promote=promote) alias_chain.append(alias) for (dupe_opts, dupe_col) in dupe_set: self.query.update_dupe_avoidance(dupe_opts, dupe_col, alias) if self.query.alias_map[root_alias][JOIN_TYPE] == self.query.LOUTER: self.query.promote_alias_chain(alias_chain, True) else: alias = root_alias dedupe = f.column in opts.duplicate_targets if dupe_set or dedupe: avoid.update(self.query.dupe_avoidance.get((id(opts), f.column), ())) if dedupe: dupe_set.add((opts, f.column)) alias = self.query.join((alias, table, f.column, f.rel.get_related_field().column), exclusions=used.union(avoid), promote=promote) used.add(alias) columns, aliases = self.get_default_columns(start_alias=alias, opts=f.rel.to._meta, as_pairs=True) self.query.related_select_cols.extend(columns) if self.query.alias_map[alias][JOIN_TYPE] == self.query.LOUTER: self.query.promote_alias_chain(aliases, True) self.query.related_select_fields.extend(f.rel.to._meta.fields) if restricted: next = requested.get(f.name, {}) else: next = False new_nullable = f.null or promote for dupe_opts, dupe_col in dupe_set: self.query.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, avoid) if restricted: related_fields = [ (o.field, o.model) for o in opts.get_all_related_objects() if o.field.unique ] for f, model in related_fields: if not select_related_descend(f, restricted, requested, reverse=True): continue # The "avoid" set is aliases we want to avoid just for this # particular branch of the recursion. They aren't permanently # forbidden from reuse in the related selection tables (which is # what "used" specifies). avoid = avoid_set.copy() dupe_set = orig_dupe_set.copy() table = model._meta.db_table int_opts = opts alias = root_alias alias_chain = [] chain = opts.get_base_chain(f.rel.to) if chain is not None: for int_model in chain: # Proxy model have elements in base chain # with no parents, assign the new options # object and skip to the next base in that # case if not int_opts.parents[int_model]: int_opts = int_model._meta continue lhs_col = int_opts.parents[int_model].column dedupe = lhs_col in opts.duplicate_targets if dedupe: avoid.update((self.query.dupe_avoidance.get(id(opts), lhs_col), ())) dupe_set.add((opts, lhs_col)) int_opts = int_model._meta alias = self.query.join( (alias, int_opts.db_table, lhs_col, int_opts.pk.column), exclusions=used, promote=True, reuse=used ) alias_chain.append(alias) for dupe_opts, dupe_col in dupe_set: self.query.update_dupe_avoidance(dupe_opts, dupe_col, alias) dedupe = f.column in opts.duplicate_targets if dupe_set or dedupe: avoid.update(self.query.dupe_avoidance.get((id(opts), f.column), ())) if dedupe: dupe_set.add((opts, f.column)) alias = self.query.join( (alias, table, f.rel.get_related_field().column, f.column), exclusions=used.union(avoid), promote=True ) used.add(alias) columns, aliases = self.get_default_columns(start_alias=alias, opts=model._meta, as_pairs=True, local_only=True) self.query.related_select_cols.extend(columns) self.query.related_select_fields.extend(model._meta.fields) next = requested.get(f.related_query_name(), {}) new_nullable = f.null or None self.fill_related_selections(model._meta, table, cur_depth+1, used, next, restricted, new_nullable) def deferred_to_columns(self): """ Converts the self.deferred_loading data structure to mapping of table names to sets of column names which are to be loaded. Returns the dictionary. """ columns = {} self.query.deferred_to_data(columns, self.query.deferred_to_columns_cb) return columns def results_iter(self): """ Returns an iterator over the results from executing this query. """ resolve_columns = hasattr(self, 'resolve_columns') fields = None has_aggregate_select = bool(self.query.aggregate_select) # Set transaction dirty if we're using SELECT FOR UPDATE to ensure # a subsequent commit/rollback is executed, so any database locks # are released. if self.query.select_for_update and transaction.is_managed(self.using): transaction.set_dirty(self.using) 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.query.select_fields: fields = self.query.select_fields + self.query.related_select_fields else: fields = self.query.model._meta.fields # If the field was deferred, exclude it from being passed # into `resolve_columns` because it wasn't selected. only_load = self.deferred_to_columns() if only_load: db_table = self.query.model._meta.db_table fields = [f for f in fields if db_table in only_load and f.column in only_load[db_table]] row = self.resolve_columns(row, fields) if has_aggregate_select: aggregate_start = len(self.query.extra_select.keys()) + len(self.query.select) aggregate_end = aggregate_start + len(self.query.aggregate_select) row = tuple(row[:aggregate_start]) + tuple([ self.query.resolve_aggregate(value, aggregate, self.connection) for (alias, aggregate), value in zip(self.query.aggregate_select.items(), row[aggregate_start:aggregate_end]) ]) + tuple(row[aggregate_end:]) yield row 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. In this last case, the cursor is returned if any query is executed, since it's used by subclasses such as InsertQuery). It's possible, however, that no query is needed, as the filters describe an empty set. In that case, None is returned, to avoid any unnecessary database interaction. """ 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.query.ordering_aliases: return cursor.fetchone()[:-len(self.query.ordering_aliases)] return cursor.fetchone() # The MULTI case. if self.query.ordering_aliases: result = order_modified_iter(cursor, len(self.query.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 class SQLInsertCompiler(SQLCompiler): def placeholder(self, field, val): if field is None: # A field value of None means the value is raw. return val elif hasattr(field, 'get_placeholder'): # Some fields (e.g. geo fields) need special munging before # they can be inserted. return field.get_placeholder(val, self.connection) else: # Return the common case for the placeholder return '%s' def as_sql(self): # We don't need quote_name_unless_alias() here, since these are all # going to be column names (so we can avoid the extra overhead). qn = self.connection.ops.quote_name opts = self.query.model._meta result = ['INSERT INTO %s' % qn(opts.db_table)] has_fields = bool(self.query.fields) fields = self.query.fields if has_fields else [opts.pk] result.append('(%s)' % ', '.join([qn(f.column) for f in fields])) if has_fields: params = values = [ [ f.get_db_prep_save(getattr(obj, f.attname) if self.query.raw else f.pre_save(obj, True), connection=self.connection) for f in fields ] for obj in self.query.objs ] else: values = [[self.connection.ops.pk_default_value()] for obj in self.query.objs] params = [[]] fields = [None] can_bulk = (not any(hasattr(field, "get_placeholder") for field in fields) and not self.return_id and self.connection.features.has_bulk_insert) if can_bulk: placeholders = [["%s"] * len(fields)] else: placeholders = [ [self.placeholder(field, v) for field, v in izip(fields, val)] for val in values ] # Oracle Spatial needs to remove some values due to #10888 params = self.connection.ops.modify_insert_params(placeholders, params) if self.return_id and self.connection.features.can_return_id_from_insert: params = params[0] col = "%s.%s" % (qn(opts.db_table), qn(opts.pk.column)) result.append("VALUES (%s)" % ", ".join(placeholders[0])) r_fmt, r_params = self.connection.ops.return_insert_id() result.append(r_fmt % col) params += r_params return [(" ".join(result), tuple(params))] if can_bulk: result.append(self.connection.ops.bulk_insert_sql(fields, len(values))) return [(" ".join(result), tuple([v for val in values for v in val]))] else: return [ (" ".join(result + ["VALUES (%s)" % ", ".join(p)]), vals) for p, vals in izip(placeholders, params) ] def execute_sql(self, return_id=False): assert not (return_id and len(self.query.objs) != 1) self.return_id = return_id cursor = self.connection.cursor() for sql, params in self.as_sql(): cursor.execute(sql, params) if not (return_id and cursor): return if self.connection.features.can_return_id_from_insert: return self.connection.ops.fetch_returned_insert_id(cursor) return self.connection.ops.last_insert_id(cursor, self.query.model._meta.db_table, self.query.model._meta.pk.column) class SQLDeleteCompiler(SQLCompiler): def as_sql(self): """ Creates the SQL for this query. Returns the SQL string and list of parameters. """ assert len(self.query.tables) == 1, \ "Can only delete from one table at a time." qn = self.quote_name_unless_alias result = ['DELETE FROM %s' % qn(self.query.tables[0])] where, params = self.query.where.as_sql(qn=qn, connection=self.connection) result.append('WHERE %s' % where) return ' '.join(result), tuple(params) class SQLUpdateCompiler(SQLCompiler): def as_sql(self): """ Creates the SQL for this query. Returns the SQL string and list of parameters. """ self.pre_sql_setup() if not self.query.values: return '', () table = self.query.tables[0] qn = self.quote_name_unless_alias result = ['UPDATE %s' % qn(table)] result.append('SET') values, update_params = [], [] for field, model, val in self.query.values: if hasattr(val, 'prepare_database_save'): val = val.prepare_database_save(field) else: val = field.get_db_prep_save(val, connection=self.connection) # Getting the placeholder for the field. if hasattr(field, 'get_placeholder'): placeholder = field.get_placeholder(val, self.connection) else: placeholder = '%s' if hasattr(val, 'evaluate'): val = SQLEvaluator(val, self.query, allow_joins=False) name = field.column if hasattr(val, 'as_sql'): sql, params = val.as_sql(qn, self.connection) values.append('%s = %s' % (qn(name), sql)) update_params.extend(params) elif val is not None: values.append('%s = %s' % (qn(name), placeholder)) update_params.append(val) else: values.append('%s = NULL' % qn(name)) if not values: return '', () result.append(', '.join(values)) where, params = self.query.where.as_sql(qn=qn, connection=self.connection) if where: result.append('WHERE %s' % where) return ' '.join(result), tuple(update_params + params) def execute_sql(self, result_type): """ Execute the specified update. Returns the number of rows affected by the primary update query. The "primary update query" is the first non-empty query that is executed. Row counts for any subsequent, related queries are not available. """ cursor = super(SQLUpdateCompiler, self).execute_sql(result_type) rows = cursor and cursor.rowcount or 0 is_empty = cursor is None del cursor for query in self.query.get_related_updates(): aux_rows = query.get_compiler(self.using).execute_sql(result_type) if is_empty: rows = aux_rows is_empty = False return rows def pre_sql_setup(self): """ If the update depends on results from other tables, we need to do some munging of the "where" conditions to match the format required for (portable) SQL updates. That is done here. Further, if we are going to be running multiple updates, we pull out the id values to update at this point so that they don't change as a result of the progressive updates. """ self.query.select_related = False self.query.clear_ordering(True) super(SQLUpdateCompiler, self).pre_sql_setup() count = self.query.count_active_tables() if not self.query.related_updates and count == 1: return # We need to use a sub-select in the where clause to filter on things # from other tables. query = self.query.clone(klass=Query) query.bump_prefix() query.extra = {} query.select = [] query.add_fields([query.model._meta.pk.name]) must_pre_select = count > 1 and not self.connection.features.update_can_self_select # Now we adjust the current query: reset the where clause and get rid # of all the tables we don't need (since they're in the sub-select). self.query.where = self.query.where_class() if self.query.related_updates or must_pre_select: # Either we're using the idents in multiple update queries (so # don't want them to change), or the db backend doesn't support # selecting from the updating table (e.g. MySQL). idents = [] for rows in query.get_compiler(self.using).execute_sql(MULTI): idents.extend([r[0] for r in rows]) self.query.add_filter(('pk__in', idents)) self.query.related_ids = idents else: # The fast path. Filters and updates in one query. self.query.add_filter(('pk__in', query)) for alias in self.query.tables[1:]: self.query.alias_refcount[alias] = 0 class SQLAggregateCompiler(SQLCompiler): def as_sql(self, qn=None): """ Creates the SQL for this query. Returns the SQL string and list of parameters. """ if qn is None: qn = self.quote_name_unless_alias sql = ('SELECT %s FROM (%s) subquery' % ( ', '.join([ aggregate.as_sql(qn, self.connection) for aggregate in self.query.aggregate_select.values() ]), self.query.subquery) ) params = self.query.sub_params return (sql, params) class SQLDateCompiler(SQLCompiler): def results_iter(self): """ Returns an iterator over the results from executing this query. """ resolve_columns = hasattr(self, 'resolve_columns') if resolve_columns: from django.db.models.fields import DateTimeField fields = [DateTimeField()] else: from django.db.backends.util import typecast_timestamp needs_string_cast = self.connection.features.needs_datetime_string_cast offset = len(self.query.extra_select) for rows in self.execute_sql(MULTI): for row in rows: date = row[offset] if resolve_columns: date = self.resolve_columns(row, fields)[offset] elif needs_string_cast: date = typecast_timestamp(str(date)) yield date 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]