Update to Pydantic V2

[gatesn]

Summary

Updates betterproto to generate data classes for Pydantic V2.

The issues I ran into were:

• root_validator is deprecated
  • Replaced by model_validate(mode='after'), required updating the field validator to use getattr on the built model
• betterproto.Enum was not recognized by Pydantic as an enum type.
  • I don't have the history for why this project doesn't use IntEnum, but I worked around this by creating a Pydantic serializer that will validate integers (it does not enforce a max integer to allow for new enum variants to be added).
  • An alternate solution here would just be to include the __get_pydantic_core_schema__ function on every generated Enum class. Open to switching to this.
• Pydantic no longer raises ValueError when constructing a data class with a missing argument.
  • I think this is ok since it now better matches the builtin behavior, I changed the test to allow this.
  • I added a test demonstrating that Pydantic will validate the correct type.

Fixes #530

Checklist

• If code changes were made then they have been tested.
  • I have updated the documentation to reflect the changes.
• This PR fixes an issue.
• This PR adds something new (e.g. new method or parameters).
  • This change has an associated test.
• This PR is a breaking change (e.g. methods or parameters removed/renamed)
• This PR is not a code change (e.g. documentation, README, ...)

[gatesn]

I inlined the Pydantic serializer into every generated enum since typing.Annotated only exists in Python >=3.9

[Gobot1234]

Fwiw if the code is easier to generate/understand use typing_extensions.Annotated. It is already a dep of the project and probably pydantic

[gatesn]

I don't mind either way, your call

[gatesn]

I just discovered the poe format task 🤦

[Gobot1234]

I don't mind either way, your call

code looks fine to me as is :)

[cetanu]

relock and the checks should go green

[gatesn]

Should be fixed

[gatesn]

@Gobot1234 I've resolved conflicts against develop. Is this g2g now?

[Gobot1234]

CI looks good :)

[gatesn]

Reverted the import change

[Gobot1234]

This needs reverting

[gatesn]

Yup, just caught that, apologies

[gatesn]

@Gobot1234 are we all set? Keen to start getting some model validation in my protos 😄

[Gobot1234]

Yep, thanks for this!

[gatesn]

@Gobot1234 would you be open to publishing a v2.0.0-beta7?

[Gobot1234]

If you can write up the changelog I'm happy to merge it (I don't have perms to merge without review) and publish.

[gatesn]

Actually it looks like there’s some weird behaviour with the PLACEHOLDER object. Should that be replaced with default primitive value for the given type? Not sure…

[JitPackJoyride]

@Gobot1234 I thought you specifically said you didn't want this @generated label on these files during this PR: #568.

I'm opening a PR for a CHANGELOG and bump in version, and wondering if you think this is blocking.

[Gobot1234]

Ah yep good catch, would you mind removing it in your PR so it's easier to merge?