UUID type Field doesn't support strict specification

[EvanED]

Initial Checks

• I confirm that I'm using Pydantic V2

Description

This seems to be closely related to #7759 which is marked fixed, but if I installed the current main correctly it doesn't seem to be fixed there.

I would like to make a class that is, in general, strict, but where that strictness is relaxed for UUID fields so I can get conversions from strings rather than have to pre-convert those:

class UnstrictExample(pydantic.BaseModel):
    model_config = pydantic.ConfigDict(strict=True)
    id: uuid.UUID = pydantic.Field(strict=False)
    val: int

With Pydantic 2.1, this works:

>>> import pydantic
>>> import uuid
>>> class UnstrictExample(pydantic.BaseModel):
...     model_config = pydantic.ConfigDict(strict=True)
...     id: uuid.UUID = pydantic.Field(strict=False)
...     val: int
... 
>>> UnstrictExample(id="e9dbca76-6adb-4e1c-af87-ac7b9e24fded", val=123)
UnstrictExample(id=UUID('e9dbca76-6adb-4e1c-af87-ac7b9e24fded'), val=123)
>>> pydantic.version.VERSION
'2.1.1'

However, upgrade to 2.2, and it does not:

>>> class UnstrictExample(pydantic.BaseModel):
...     model_config = pydantic.ConfigDict(strict=True)
...     id: uuid.UUID = pydantic.Field(strict=False)
...     val: int
... 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.11/site-packages/pydantic/_internal/_model_construction.py", line 178, in __new__
    complete_model_class(
  File "/usr/local/lib/python3.11/site-packages/pydantic/_internal/_model_construction.py", line 468, in complete_model_class
    schema = cls.__get_pydantic_core_schema__(cls, handler)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  File "/usr/local/lib/python3.11/site-packages/pydantic/_internal/_generate_schema.py", line 1644, in _apply_single_annotation
    maybe_updated_schema = _known_annotated_metadata.apply_known_metadata(metadata, schema.copy())
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/pydantic/_internal/_known_annotated_metadata.py", line 239, in apply_known_metadata
    raise RuntimeError(f'Unable to apply constraint {constraint} to schema {schema_type}')
RuntimeError: Unable to apply constraint strict to schema uuid
>>> pydantic.version.VERSION
'2.2.1'

and this remains true if I pip install 'git+https://github.com/pydantic/pydantic@main#egg=pydantic' (though it may be installing pydantic-core from somewhere else...? I'm not sure I'm checking current trunk correctly; sorry if this is fixed after all.)

Example Code

import pydantic
import uuid
class UnstrictExample(pydantic.BaseModel):
    model_config = pydantic.ConfigDict(strict=True)
    id: uuid.UUID = pydantic.Field(strict=False)
    val: int

Python, Pydantic & OS Version

Running from python:3.11-slim-bookworm Docker container, but I get similar with 3.8 in a local venv. Here's the version information for 2.2:

             pydantic version: 2.2.1
        pydantic-core version: 2.6.1
          pydantic-core build: profile=release pgo=true
                 install path: /usr/local/lib/python3.11/site-packages/pydantic
               python version: 3.11.4 (main, Jul 28 2023, 05:12:06) [GCC 12.2.0]
                     platform: Linux-5.4.0-150-generic-x86_64-with-glibc2.36
     optional deps. installed: ['typing-extensions']

[EvanED]

Actually... this is a somewhat different problem than I thought, and got a slightly more simple example. Turns out the class-level config doesn't matter, and even this is sufficient:

>>> class UnstrictExample(pydantic.BaseModel):
...     id: uuid.UUID = pydantic.Field(strict=False)
...     val: int
... 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.11/site-packages/pydantic/_internal/_model_construction.py", line 178, in __new__
    complete_model_class(
...
  File "/usr/local/lib/python3.11/site-packages/pydantic/_internal/_known_annotated_metadata.py", line 239, in apply_known_metadata
    raise RuntimeError(f'Unable to apply constraint {constraint} to schema {schema_type}')
RuntimeError: Unable to apply constraint strict to schema uuid

[sydney-runkle]

@EvanED,

Thanks for reporting this. This indeed looks like a bug 🐛. I'll work to get a fix out for this soon 👍.

[EvanED]

Appreciated; thanks a bundle!

[sydney-runkle]

Just merged a fix. This should be fixed in the next release 😄.

[EvanED]

A couple hours to confirm and less than two days for a fix... absolutely brilliant. Thank you very much, I look forward it making a release!