Passing data to default_factory in with_default_schema

[RolandSaur]

I am trying to replace a model with a default model in case validation fails. But I would like to customize the default model based on the error message.

For this I am using with_default_schema and am trying to pass data to default_factory.

My Question: How to pass the validation error to the default_factory of with_default_schema?

Minimal Example:
The Minimal Example validates an Item and calls error_handler because of a validation error. This part works. However from the docs it is not clear how to pass anything to the error_handler. context is simply None.

from pydantic import BaseModel, Field, model_validator
from pydantic_core import SchemaValidator, core_schema
from typing import Any

class Item(BaseModel):
    value: float = Field(ge=0)
    weight: float = Field(ge=0)


def error_handler(context: dict[str, Any]) -> Item:
    return Item(value=0, weight=0)

default_item_schema = core_schema.with_default_schema(
    schema=Item.__pydantic_core_schema__,
    default_factory=error_handler,
    default_factory_takes_data=True,
    on_error="default",
)
item_validator = SchemaValidator(default_item_schema)

default_item = item_validator.validate_python({"value": -5, "weight": 4})

System:

• pydantic version 2.10.3
• python version 3.12.3
• OS: Kubuntu 24.04