dmfs
commented
8 years ago To workaround this limitation, I've created a custom ValidationMixin that calls the validator first:
class ValidationMixin(object):
# make sure to call _validator before we do as the very first validation step
def _do_validate(self, value):
if self._validator is not None:
newvalue = self._validator(self, value)
if newvalue is not None:
value = newvalue
return super(ValidationMixin, self)._do_validate(value)
# A KeyProperty that allows a validator to generate a Key.
# In addition it serializes to just the id of the key
class KeyProperty(ValidationMixin, ndb.KeyProperty):
# return just the id of the key
def _get_for_dict(self, entity):
value = self._get_value(entity)
if self._repeated:
return [v.id() for v in value]
elif value is not None:
return value.id()
return valueWith a validator like this
def key_validator(kind):
def validator(prop, value):
if not isinstance(value, ndb.Key):
return ndb.Key(kind, value)
return value
return validatorI can have a property like this:
foo = KeyProperty('Foo', validator=key_validator('Foo'))Which makes it easy to serialize and deserialize KeyPropertties from/to JSON.
In model.py, line 1092
_call_shallow_validationis called before any_validatorthat might exists.Wouldn't it be better to perform the shallow validation after a custom validator? The validator might be able to "fix" any invalid values (that's what it's meant for, isn't it)?
My use case is calling
populatewith members that contain ids of Keys to updateKeyProperties.i.e. my property looks like this:
That's particularly useful to update a
KeyPropertyusingpopulatelike so:Which in turn is useful to update a
KeyPropertyby specifying the id in JSON like so:Another use case would be to allow a
DateTimePropertyto take an ISO8601 date-time string by converting it to a datetime in the validator (I believe that's not possible right now). That again is very useful when loading JSON data.