/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

  1. from django.core.exceptions import FieldError
  2. from django.db.models.fields import FieldDoesNotExist
  3. from django.db.models.sql.constants import LOOKUP_SEP
  4. class SQLEvaluator(object):
  5. def __init__(self, expression, query, allow_joins=True):
  6. self.expression = expression
  7. self.opts = query.get_meta()
  8. self.cols = {}
  9. self.contains_aggregate = False
  10. self.expression.prepare(self, query, allow_joins)
  11. def prepare(self):
  12. return self
  13. def as_sql(self, qn, connection):
  14. return self.expression.evaluate(self, qn, connection)
  15. def relabel_aliases(self, change_map):
  16. for node, col in self.cols.items():
  17. if hasattr(col, "relabel_aliases"):
  18. col.relabel_aliases(change_map)
  19. else:
  20. self.cols[node] = (change_map.get(col[0], col[0]), col[1])
  21. #####################################################
  22. # Vistor methods for initial expression preparation #
  23. #####################################################
  24. def prepare_node(self, node, query, allow_joins):
  25. for child in node.children:
  26. if hasattr(child, 'prepare'):
  27. child.prepare(self, query, allow_joins)
  28. def prepare_leaf(self, node, query, allow_joins):
  29. if not allow_joins and LOOKUP_SEP in node.name:
  30. raise FieldError("Joined field references are not permitted in this query")
  31. field_list = node.name.split(LOOKUP_SEP)
  32. if (len(field_list) == 1 and
  33. node.name in query.aggregate_select.keys()):
  34. self.contains_aggregate = True
  35. self.cols[node] = query.aggregate_select[node.name]
  36. else:
  37. try:
  38. field, source, opts, join_list, last, _ = query.setup_joins(
  39. field_list, query.get_meta(),
  40. query.get_initial_alias(), False)
  41. col, _, join_list = query.trim_joins(source, join_list, last, False)
  42. self.cols[node] = (join_list[-1], col)
  43. except FieldDoesNotExist:
  44. raise FieldError("Cannot resolve keyword %r into field. "
  45. "Choices are: %s" % (self.name,
  46. [f.name for f in self.opts.fields]))
  47. ##################################################
  48. # Vistor methods for final expression evaluation #
  49. ##################################################
  50. def evaluate_node(self, node, qn, connection):
  51. expressions = []
  52. expression_params = []
  53. for child in node.children:
  54. if hasattr(child, 'evaluate'):
  55. sql, params = child.evaluate(self, qn, connection)
  56. else:
  57. sql, params = '%s', (child,)
  58. if len(getattr(child, 'children', [])) > 1:
  59. format = '(%s)'
  60. else:
  61. format = '%s'
  62. if sql:
  63. expressions.append(format % sql)
  64. expression_params.extend(params)
  65. return connection.ops.combine_expression(node.connector, expressions), expression_params
  66. def evaluate_leaf(self, node, qn, connection):
  67. col = self.cols[node]
  68. if hasattr(col, 'as_sql'):
  69. return col.as_sql(qn, connection), ()
  70. else:
  71. return '%s.%s' % (qn(col[0]), qn(col[1])), ()
  72. def evaluate_date_modifier_node(self, node, qn, connection):
  73. timedelta = node.children.pop()
  74. sql, params = self.evaluate_node(node, qn, connection)
  75. if timedelta.days == 0 and timedelta.seconds == 0 and \
  76. timedelta.microseconds == 0:
  77. return sql, params
  78. return connection.ops.date_interval_sql(sql, node.connector, timedelta), params