Multiple checks for custom type in Pydantic

Question

Is there any way to achieve a multiple Exception raise call for a custom type?

from pydantic import BaseModel

class CustomType(object):
    @classmethod
    def validate_first(cls, *args, **kwargs):
        raise ValueError("first")
        return cls(*args, **kwargs)
    
    @classmethod
    def validate_second(cls, *args, **kwargs):
        raise ValueError("second")
        return cls(*args, **kwargs)

    @classmethod
    def __get_validators__(cls):
        yield cls.validate_first
        yield cls.validate_second


class MyModel(BaseModel):
    model_field: CustomType

data = {
    "model_field": 1,
}

MyModel(**data)

I see only the first ValidationError being raised

ValidationError: 1 validation error for MyModel
model_field
  first (type=value_error)

But I would like to get this result

ValidationError: 1 validation error for MyModel
model_field
  first (type=value_error)
model_field
  second (type=value_error)

As you know, if an exception is raised in the generator, it terminates (raises StopIteration)

Is there a way around this?

Answer 1

I believe there is no way around that and you have to raise a single ValueError for all the validations of a field, but you can pass a list or a dict to a ValueError if that helps:

import pydantic


class Foo(pydantic.BaseModel):
    bar: str
    baz: str

    @pydantic.validator("bar")
    def _validate_bar(cls, bar: str) -> str:
        raise ValueError(["first", "second"])

    @pydantic.validator("baz")
    def _validate_baz(cls, bar: str) -> str:
        raise ValueError({"first": "blah blah", "second": "blah blah"})


Foo(bar="a", baz="b")

# Output:
# pydantic.error_wrappers.ValidationError: 2 validation errors for Foo
# bar
#   ['first', 'second'] (type=value_error)
# baz
#   {'first': 'blah blah', 'second': 'blah blah'} (type=value_error)