hydra_zen.third_party.pydantic.pydantic_parser#

hydra_zen.third_party.pydantic.pydantic_parser(target, *, parser=<function validate_call.<locals>.validate>)[source]#

A target-wrapper that adds pydantic parsing to the target.

This can be passed to instantiate as a _target_wrapper_ to add pydantic parsing to the (recursive) instantiation of the target.

Parameters:

targetCallable

parserType[pydantic.validate_arguments], optional

A configured instance of pydantic’s validation decorator.

The default validator that we provide specifies:

arbitrary_types_allowed: True

Examples

from hydra_zen import builds, instantiate
from hydra_zen.third_party.pydantic import pydantic_parser

from pydantic import PositiveInt

def f(x: PositiveInt): return x

good_conf = builds(f, x=10)
bad_conf = builds(f, x=-3)

>>> instantiate(good_conf, _target_wrapper_=pydantic_parser)
10
>>> instantiate(bad_conf, _target_wrapper_=pydantic_parser)
ValidationError: 1 validation error for f (...)

This also enables type conversion / parsing. E.g. Hydra can only produce lists from the CLI, but this parsing layer can convert them based on the annotated type. (Note: this only works for pydantic v2 and higher.)

>>> def g(x: tuple): return x
>>> conf = builds(g, x=[1, 2, 3])
>>> instantiate(conf, _target_wrapper_=pydantic_parser)
(1, 2, 3)