PY-MODE0003 · approved_model_foundation

Require direct Pydantic models to use an established approved house base.

This is a deterministic rule for python. Read its implementation.

Definition

First establish project policy, either by finding a module anywhere in the repository that imports a foundation from patos or from a common.bases module, or by finding a base the project itself owns, one declaring no fields that other classes already derive. A module named after a folder establishes nothing on its own, since a name says nothing about what a module declares. Then inspect project-owned top-level classes and report direct subclasses of an imported pydantic.BaseModel that do not also inherit an approved base. Resolve direct imports, module imports, and aliases through the bindings each file states. Each bypassing class contributes one to the result.

Evidence

Each finding identifies the direct model class and its source range. Which foundations count as approved is the provider’s single project-specific input, and it recognizes the two house homes for one. The value is the number of classes deriving pydantic.BaseModel without an approved foundation.

Exceptions

Abstain when the project has not established a house foundation. The foundation itself derives Pydantic directly by design, so a base owning no fields that states the model_config its subclasses inherit is never reported, whatever file or folder holds it. Ignore Pydantic dataclasses, RootModel, dynamic create_model calls, unresolved bases, nested classes, and subclasses of a project foundation because their Pydantic ancestry is not locally proven. The repository’s Git ignore files decide whether generated and vendored sources are in the scan, and per-rule globs can narrow it further.

Examples

Bad

After `from patos import FrozenModel` establishes the policy, this direct foundation bypasses
it.

.. code-block:: python

   from pydantic import BaseModel

   class User(BaseModel):
       name. str

Good

The project-owned foundation makes mutability and validation policy explicit.

.. code-block:: python

from patos import FrozenModel

class User(FrozenModel): name. str

References

• Cites “Pydantic documentation”, models. Open reference
• Cites “Pydantic documentation”, custom base model guidance. Open reference
• Cites “PEP 8, Style Guide for Python Code”, public and internal interfaces. Open reference