+from PLC.Faults import *
+from PLC.Parameter import Parameter, Mixed, python_type
+
+class Filter(Parameter, dict):
+ """
+ A type of parameter that represents a filter on one or more
+ columns of a database table. fields should be a dictionary of
+ field names and types, e.g.
+
+ {'node_id': Parameter(int, "Node identifier"),
+ 'hostname': Parameter(int, "Fully qualified hostname", max = 255),
+ ...}
+
+ Only filters on non-sequence type fields are supported.
+
+ filter should be a dictionary of field names and values
+ representing an intersection (if join_with is AND) or union (if
+ join_with is OR) filter. If a value is a sequence type, then it
+ should represent a list of possible values for that field.
+ """
+
+ def __init__(self, fields = {}, filter = {}, doc = "Attribute filter"):
+ # Store the filter in our dict instance
+ dict.__init__(self, filter)
+
+ # Declare ourselves as a type of parameter that can take
+ # either a value or a list of values for each of the specified
+ # fields.
+ self.fields = {}
+
+ for field, expected in fields.iteritems():
+ # Cannot filter on sequences
+ if python_type(expected) in (list, tuple, set):
+ continue
+
+ # Accept either a value or a list of values of the specified type
+ self.fields[field] = Mixed(expected, [expected])
+
+ Parameter.__init__(self, self.fields, doc = doc)
+
+ def sql(self, api, join_with = "AND"):
+ """
+ Returns a SQL conditional that represents this filter.
+ """
+
+ # So that we always return something
+ if join_with == "AND":
+ conditionals = ["True"]
+ elif join_with == "OR":
+ conditionals = ["False"]
+ else:
+ assert join_with in ("AND", "OR")
+
+ for field, value in self.iteritems():
+ if field not in self.fields:
+ raise PLCInvalidArgument, "Invalid filter field '%s'" % field
+
+ if isinstance(value, (list, tuple, set)):
+ # Turn empty list into (NULL) instead of invalid ()
+ if not value:
+ value = [None]
+
+ operator = "IN"
+ value = map(str, map(api.db.quote, value))
+ value = "(%s)" % ", ".join(value)
+ else:
+ if value is None:
+ operator = "IS"
+ value = "NULL"
+ else:
+ operator = "="
+ value = str(api.db.quote(value))
+
+ conditionals.append("%s %s %s" % (field, operator, value))
+
+ return (" %s " % join_with).join(conditionals)