Using original input data

If you want to use the original, unprocessed input, you can add pass_original=True to post_load <marshmallow.decorators.post_load> or validates_schema <marshmallow.decorators.validates_schema>.

.. code-block:: python

from marshmallow import Schema, fields, post_load, ValidationError


class MySchema(Schema):
    foo = fields.Int()
    bar = fields.Int()

    @post_load(pass_original=True)
    def add_baz_to_bar(self, data, original_data, **kwargs):
        baz = original_data.get("baz")
        if baz:
            data["bar"] = data["bar"] + baz
        return data


schema = MySchema()
schema.load({"foo": 1, "bar": 2, "baz": 3})
# {'foo': 1, 'bar': 5}

.. seealso::

The default behavior for unspecified fields can be controlled with the unknown option, see :ref:Handling Unknown Fields <unknown> for more information.