# The `post_generated` decorator

The `post_generated` decorator wraps a `classmethod` into a `PostGenerated` field. This is useful when the post generated field depends on the current factory, usually its `__faker__` and/or `__random__` attribute. For example:

Using the `post_generated` decorator

    from dataclasses import dataclass, field
    from datetime import datetime, timedelta

    from polyfactory.decorators import post_generated
    from polyfactory.factories import DataclassFactory

    @dataclass
    class DatetimeRange:
        to_dt: datetime
        from_dt: datetime = field(default_factory=datetime.now)

    class DatetimeRangeFactory(DataclassFactory[DatetimeRange]):
        @post_generated
        @classmethod
        def to_dt(cls, from_dt: datetime) -> datetime:
            return from_dt + cls.__faker__.time_delta("+3d")

    def test_post_generated() -> None:
        date_range_instance = DatetimeRangeFactory.build()
        assert date_range_instance.to_dt > date_range_instance.from_dt
        assert date_range_instance.to_dt < date_range_instance.from_dt + timedelta(days=3)

All classmethod parameters after `cls` must be named as the fields this post generated field depends on.