Migrate to pydantic v2

[Leobouloc]

Purpose

As mentionned in #401 , upgrading to pydantic 2 should greatly improve performances. Also it would allow projects depending on ralph (such as warren) to upgrade more easily.

Dealing with common errors when migrating

ERROR: Extra not permitted

In conf.py, errors such as:

    super().__init__(
E   pydantic_core._pydantic_core.ValidationError: 1 validation error for Settings
E   LOCALE_ENCODING
E     Extra inputs are not permitted [type=extra_forbidden, input_value='utf-8', input_type=str]
E       For further information visit https://errors.pydantic.dev/2.1/v/extra_forbidden

may be due to a change in default behavior in models extra=ignore to extra=failure. We may set this parameter manually to fix this issue.

ERROR: Unable to generate pydantic-core schema

E   pydantic.errors.PydanticSchemaGenerationError: Unable to generate pydantic-core schema for <class 'ralph.models.xapi.base.common.IRI'>. Set `arbitrary_types_allowed=True` in the model_config to ignore this error or implement `__get_pydantic_core_schema__` on your type to fully support it.
E
E   If you got this error by calling handler(<some type>) within `__get_pydantic_core_schema__` then you likely need to call `handler.generate_schema(<some type>)` since we do not call `__get_pydantic_core_schema__` on `<some type>` otherwise to avoid infinite recursion.
E

To fix this we change the way we define classes.

Previously in Ralph

class CommaSeparatedTuple(BaseModel):
    @model_validator(mode='before')
    @classmethod
    def validate(cls, value: Union[str, Tuple[str]]) -> Tuple[str]:
        """Checks whether the value is a comma separated string or a tuple."""

        if isinstance(value, tuple):
            return value

        if isinstance(value, str):
            return tuple(value.split(","))

        raise TypeError("Invalid comma separated list")

New in Ralph

def validate_comma_separated_tuple(value: Union[str, Tuple[str, ...]]) -> Tuple[str]:
    """Checks whether the value is a comma separated string or a tuple."""

    if isinstance(value, tuple):
        return value

    if isinstance(value, str):
        return tuple(value.split(","))

    raise TypeError("Invalid comma separated list")

CommaSeparatedTuple = Annotated[Union[str, Tuple[str, ...]], AfterValidator(validate_comma_separated_tuple)]

ERROR: Missing values

A recurrent error is the one below, which should be linked to the change of behavior when using Optional[...] in Pydantic V2. Previously, it would assign a default value of None, which is no longer the case. This should have been dealt with by bump-pydantic but was not always the case. It would be nice to know why before confirming this solution.

src/ralph/models/xapi/video/statements.py:85: in VideoPlayed
    verb: PlayedVerb = PlayedVerb()
E   pydantic_core._pydantic_core.ValidationError: 1 validation error for PlayedVerb
E   display
E     Field required [type=missing, input_value={}, input_type=dict]
E       For further information visit https://errors.pydantic.dev/2.1/v/missing

Previously in Ralph

class VideoActivity(BaseXapiActivity):
    name: Optional[Dict[Literal[LANG_EN_US_DISPLAY], str]]

New in Ralph

class VideoActivity(BaseXapiActivity):
    name: Optional[Dict[Literal[LANG_EN_US_DISPLAY], str]] = None

[Leobouloc]

"I wonder if setting a default value for this field makes it not required" Originally commented by @quitterie-lcs

[wilbrdt]

Closing as it is done in #550