Using original input data¶

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

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}