marshmalling.Unmarshaller ignoring None data

marshmalling.Unmarshaller seems to ignore None data and don’t try to validate passed data, even if there is required fields.

What the point having a validation library if we have to validate ourselves the “basic” case of None data?

Just asking the question, because it really doesn’t seems logical to me (and because I had to handle myself this issue in my own code…)

[sloria]

Schema#load and Schema#validate responsibility is to validate dict data, by default. None, False, numbers, as well as arbitrary complex objects, are outside their API boundary.

As mentioned above, you can use pre_load to preprocess inputs before they are validated.

from marshmallow import Schema, fields, pre_load

class MySchema(Schema):
    required_field = fields.Field(required=True)

    @pre_load
    def ensure_dict(self, data):
        return data or {}

schema = MySchema()
print(schema.validate(None))
# {'required_field': ['Missing data for required field']}

[sloria]

There’s this section of the docs: https://marshmallow.readthedocs.org/en/latest/quickstart.html#deserializing-objects-loading

The opposite of the dump method is the load method, which deserializes an input dictionary to an application-level data structure.

The API ref for load also specifies that the data argument is a dict: https://marshmallow.readthedocs.org/en/latest/api_reference.html#marshmallow.Schema.load .

I welcome any suggestions for making this clearer. Send a PR if you’re feeling generous! =)