def get(self, cls, **attr_filter):
attr_filter = dict_to_db_values_dict(attr_filter)
# Workaround that allows nodes and relationships with no
# attrs to be saved. `save` will cause this method to be called
# with an empty attr_filter, and when it receives None, will add
# a new object.
if not attr_filter:
return None
type_registry = self.type_registry
unique_attrs = [key for _, key in type_registry.get_unique_attrs(cls)]
query_params = {
key: value
for key, value in attr_filter.items()
if key in unique_attrs
and value is not None
}
if not query_params:
raise ValueError(
'No relevant indexes found when calling get for class: {}'
' with filter {}'.format(cls, attr_filter)
)
labels = type_registry.get_labels_for_type(cls)
# since we found an index, we have at least one label
node_declaration = 'n:' + ':'.join(labels)
params = parameter_map(attr_filter, 'params')
return self.query_single(
"MATCH (%s %s) RETURN n" % (node_declaration, params),
params=attr_filter)
def test_parameter_map():
assert parameter_map({'foo': 'bar', 'baz': 'ಠ_ಠ'}, "params") == (
'{foo: {params}.foo, baz: {params}.baz}'
)
