/bangkokhotel/lib/python2.5/site-packages/django/db/models/sql/expressions.py
https://bitbucket.org/luisrodriguez/bangkokhotel · Python · 97 lines · 72 code · 19 blank · 6 comment · 23 complexity · 8d1a6d3bdc8f809409646947962d7e40 MD5 · raw file
- from django.core.exceptions import FieldError
- from django.db.models.fields import FieldDoesNotExist
- from django.db.models.sql.constants import LOOKUP_SEP
- class SQLEvaluator(object):
- def __init__(self, expression, query, allow_joins=True):
- self.expression = expression
- self.opts = query.get_meta()
- self.cols = {}
- self.contains_aggregate = False
- self.expression.prepare(self, query, allow_joins)
- def prepare(self):
- return self
- def as_sql(self, qn, connection):
- return self.expression.evaluate(self, qn, connection)
- def relabel_aliases(self, change_map):
- for node, col in self.cols.items():
- if hasattr(col, "relabel_aliases"):
- col.relabel_aliases(change_map)
- else:
- self.cols[node] = (change_map.get(col[0], col[0]), col[1])
- #####################################################
- # Vistor methods for initial expression preparation #
- #####################################################
- def prepare_node(self, node, query, allow_joins):
- for child in node.children:
- if hasattr(child, 'prepare'):
- child.prepare(self, query, allow_joins)
- def prepare_leaf(self, node, query, allow_joins):
- if not allow_joins and LOOKUP_SEP in node.name:
- raise FieldError("Joined field references are not permitted in this query")
- field_list = node.name.split(LOOKUP_SEP)
- if (len(field_list) == 1 and
- node.name in query.aggregate_select.keys()):
- self.contains_aggregate = True
- self.cols[node] = query.aggregate_select[node.name]
- else:
- try:
- field, source, opts, join_list, last, _ = query.setup_joins(
- field_list, query.get_meta(),
- query.get_initial_alias(), False)
- col, _, join_list = query.trim_joins(source, join_list, last, False)
- self.cols[node] = (join_list[-1], col)
- except FieldDoesNotExist:
- raise FieldError("Cannot resolve keyword %r into field. "
- "Choices are: %s" % (self.name,
- [f.name for f in self.opts.fields]))
- ##################################################
- # Vistor methods for final expression evaluation #
- ##################################################
- def evaluate_node(self, node, qn, connection):
- expressions = []
- expression_params = []
- for child in node.children:
- if hasattr(child, 'evaluate'):
- sql, params = child.evaluate(self, qn, connection)
- else:
- sql, params = '%s', (child,)
- if len(getattr(child, 'children', [])) > 1:
- format = '(%s)'
- else:
- format = '%s'
- if sql:
- expressions.append(format % sql)
- expression_params.extend(params)
- return connection.ops.combine_expression(node.connector, expressions), expression_params
- def evaluate_leaf(self, node, qn, connection):
- col = self.cols[node]
- if hasattr(col, 'as_sql'):
- return col.as_sql(qn, connection), ()
- else:
- return '%s.%s' % (qn(col[0]), qn(col[1])), ()
- def evaluate_date_modifier_node(self, node, qn, connection):
- timedelta = node.children.pop()
- sql, params = self.evaluate_node(node, qn, connection)
- if timedelta.days == 0 and timedelta.seconds == 0 and \
- timedelta.microseconds == 0:
- return sql, params
- return connection.ops.date_interval_sql(sql, node.connector, timedelta), params