More information for debugging ValidationError

[will-e-yams]

Initial Checks

• [X] I have searched Google & GitHub for similar requests and couldn't find anything
• [X] I have read and followed the docs and still think this feature is missing

Description

When a single api call builds many objects it becomes very difficult to know which model failed to validate. Currently, we have:

• ctx - An optional object which contains values required to render the error message.
• input - The input provided for validation.
• loc - The error's location as a list.
• msg - A human-readable explanation of the error.
• type - A computer-readable identifier of the error type.
• url - The URL to further information about the error.

But validation errors are needlessly obtuse:

{
  'type': 'string_type',
  'loc': ('form_name',),
  'msg': 'Input should be a valid string',
  'input': None,
  'url': 'https://errors.pydantic.dev/2.7/v/string_type'
}

Two things of note that I think are missing:

1. the model (class name) that failed
2. a stack trace so i can find it!

I'm not seeing ctx being used in ValidationError, so perhaps that could be used?

Affected Components

• [ ] Compatibility between releases
• [X] Data validation/parsing
• [ ] Data serialization - .model_dump() and .model_dump_json()
• [ ] JSON Schema
• [ ] Dataclasses
• [ ] Model Config
• [ ] Field Types - adding or changing a particular data type
• [ ] Function validation decorator
• [ ] Generic Models
• [ ] Other Model behaviour - model_construct(), pickling, private attributes, ORM mode
• [ ] Plugins and integration with other tools - mypy, FastAPI, python-devtools, Hypothesis, VS Code, PyCharm, etc.

[sydney-runkle]

Hi @will-e-yams,

Could you please provide some sort of minimal reproducible example? It's hard for us to get enough context without a runnable snippet. Thanks!