pydantic-function-models

0.1.11 · active · verified Wed Apr 15

A library designed to model Python function signatures using Pydantic, offering a modern alternative to the now-deprecated `ValidatedFunction` from Pydantic v1. It facilitates the validation of function arguments based on type hints, bridging compatibility gaps between Pydantic v1 and v2. The library is currently at version 0.1.11, with updates reflecting ongoing maintenance.

Warnings

deprecated The `ValidatedFunction` class from Pydantic v1 is deprecated in Pydantic v2. This library provides a compatible `ValidatedFunction` for Pydantic v2 environments.
Fix: Migrate usage from `pydantic.ValidatedFunction` to `pydantic_function_models.ValidatedFunction` to ensure compatibility and leverage Pydantic v2's features.
gotcha Avoid using reserved parameter names such as `v__args` and `v__kwargs` in your function signatures, as these could conflict with the internal validation logic of `pydantic-function-models`.
Fix: Rename function parameters if they clash with `v__args` or `v__kwargs` to prevent unexpected behavior.
gotcha For simple function argument validation without needing the full function signature modeling provided by `ValidatedFunction`, Pydantic v2 offers the `@validate_call` decorator, which might be a more direct solution.
Fix: Consider using `from pydantic import validate_call` directly on your function if only argument validation is required, rather than full signature modeling.
gotcha Mixing Pydantic v1 and v2 models within a single application can lead to compatibility issues, especially with nested models. While `pydantic-function-models` helps with function validation, general migration strategies for `BaseModel` compatibility should be followed.
Fix: Ensure a consistent Pydantic version across your codebase or use compatibility tools if incremental migration is necessary. Refer to Pydantic's official migration guide.

Install

pip install pydantic-function-models Install latest version

Imports

ValidatedFunction
wrong:
```
from pydantic import ValidatedFunction
```
correct:
```
from pydantic_function_models import ValidatedFunction
```
In Pydantic v2, `pydantic.ValidatedFunction` is deprecated. Use `pydantic_function_models.ValidatedFunction` as its modern replacement for modeling function signatures.

Quickstart

This example demonstrates how to wrap a Python function with `ValidatedFunction` to enable Pydantic-style argument validation. It shows both successful validation and how `ValidationError` is raised for invalid inputs.

from pydantic_function_models import ValidatedFunction

def add(a: int, b: int) -> int:
    return a + b

vf = ValidatedFunction(add)

# Example of validating arguments
args_to_validate = (1,)
kwargs_to_validate = {"b": 2}

# The library builds an internal Pydantic model for validation
# You need to map positional/keyword args to model fields
validated_data = vf.model.model_validate({
    "a": args_to_validate[0],
    "b": kwargs_to_validate["b"]
})

result = add(**validated_data.model_dump(exclude_unset=True))
print(f"Result: {result}")

# Example of invalid input
try:
    invalid_data = vf.model.model_validate({"a": "one", "b": 2})
except Exception as e:
    print(f"Validation error caught: {e}")

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