+from ldapdb import escape_ldap_filter
+
+class Constraint(BaseConstraint):
+ """
+ An object that can be passed to WhereNode.add() and knows how to
+ pre-process itself prior to including in the WhereNode.
+ """
+ def process(self, lookup_type, value):
+ """
+ Returns a tuple of data suitable for inclusion in a WhereNode
+ instance.
+ """
+ # Because of circular imports, we need to import this here.
+ from django.db.models.base import ObjectDoesNotExist
+
+ if lookup_type == 'endswith':
+ params = ["*%s" % escape_ldap_filter(value)]
+ elif lookup_type == 'startswith':
+ params = ["%s*" % escape_ldap_filter(value)]
+ elif lookup_type == 'contains':
+ params = ["*%s*" % escape_ldap_filter(value)]
+ elif lookup_type == 'exact':
+ params = [escape_ldap_filter(value)]
+ elif lookup_type == 'in':
+ params = [escape_ldap_filter(v) for v in value]
+ else:
+ raise TypeError("Field has invalid lookup: %s" % lookup_type)
+
+ try:
+ if self.field:
+ db_type = self.field.db_type()
+ else:
+ db_type = None
+ except ObjectDoesNotExist:
+ raise EmptyShortCircuit
+
+ return (self.alias, self.col, db_type), params
+
+class WhereNode(BaseWhereNode):
+ def add(self, data, connector):
+ if not isinstance(data, (list, tuple)):
+ super(WhereNode, self).add(data, connector)
+ return
+
+ # we replace the native Constraint by our own
+ obj, lookup_type, value = data
+ if hasattr(obj, "process"):
+ obj = Constraint(obj.alias, obj.col, obj.field)
+ super(WhereNode, self).add((obj, lookup_type, value), connector)
+
+ def as_sql(self):
+ bits = []
+ for item in self.children:
+ if isinstance(item, WhereNode):
+ bits.append(item.as_sql())
+ continue
+ constraint, x, y, values = item
+ if hasattr(constraint, "col"):
+ # django 1.2
+ clause = "(%s=%s)" % (constraint.col, values)
+ else:
+ # django 1.1
+ (table, column, type) = constraint
+ equal_bits = [ "(%s=%s)" % (column, value) for value in values ]
+ if len(equal_bits) == 1:
+ clause = equal_bits[0]
+ else:
+ clause = '(|%s)' % ''.join(equal_bits)
+ if self.negated:
+ bits.append('(!%s)' % clause)
+ else:
+ bits.append(clause)
+ if len(bits) == 1:
+ return bits[0]
+ elif self.connector == AND:
+ return '(&%s)' % ''.join(bits)
+ elif self.connector == OR:
+ return '(|%s)' % ''.join(bits)