class Filter:
"""Stores a single filter for comparing a field to a value"""
#: OPERATORS contains a list of comparisons and operations for running
#: queries
OPERATORS = {
'eq': lambda x, y: x == y,
'ne': lambda x, y: x != y,
'gt': lambda x, y: x > y,
'lt': lambda x, y: x < y,
'ge': lambda x, y: x >= y,
'le': lambda x, y: x <= y,
'in': lambda x, y: x in y,
'contains': lambda x, y: y in x,
}
def __init__(self, filter_obj):
"""creates a filter object from a dict"""
self.field = Field(filter_obj['field'])
self.operator = filter_obj['op']
self.value = filter_obj['value']
def run(self, document):
"""runs the test against the document, comparing the metadata field
specified by the filter's field against the provided value using the
provided operation
"""
return self.OPERATORS[self.operator](
self.field.run(document),
self.value)
@classmethod
def is_filter(cls, obj):
"""duck-types a dict to see if it looks like a filter object"""
try:
if sorted(obj.keys()) != ['field', 'op', 'value']:
return False
if obj['op'] not in cls.OPERATORS:
return False
return True
except:
return False
def test_metadata(self):
field = Field('metadata:foo.bar')
self.assertEqual(field.run(self.d), 42)
field = Field('metadata:foo.baz')
self.assertEqual(field.run(self.d), None)
def test_name(self):
field = Field('name:')
self.assertEqual(field.run(self.d), 'Test document')
def test_document(self):
field = Field('document:')
self.assertEqual(field.run(self.d), 'asdf')