Description

I'm trying to define a GQL Pydantic model w/ a JSON scalar attribute:

JSONScalar = strawberry.scalar(
    NewType("JSONScalar", Any),
    serialize=lambda v: v,
    parse_value=lambda v: json.loads(v),
    description="The GenericScalar scalar type represents a generic GraphQL scalar value that could be: List or Object."
)


class ResourcePyd(PydanticModel):
    type: str
    # TODO: Figure out how to use `Json` type for this attribute
    # spec: Optional[Json]
    # spec: Optional[str]
    spec: Optional[JSONScalar]

However I can't get Pydantic to comply:

[cloud-app] [Tue Nov  9 17:21:12 2021] Running: pytest --durations=3
[cloud-app] ImportError while loading conftest '/cloud-app/tests/conftest.py'.
[cloud-app] tests/conftest.py:24: in <module>
[cloud-app]     import app.gql_mutations as gql_mutations
[cloud-app] app/gql_mutations.py:21: in <module>
[cloud-app]     from app.gql_errors import BadRequest, NotAuthorized, InternalError
[cloud-app] app/gql_errors.py:15: in <module>
[cloud-app]     from app.models import Error, Errors, ResponseCode
[cloud-app] app/models.py:128: in <module>
[cloud-app]     class ResourcePyd(PydanticModel):
[cloud-app] pydantic/main.py:299: in pydantic.main.ModelMetaclass.__new__
[cloud-app]     ???
[cloud-app] pydantic/fields.py:411: in pydantic.fields.ModelField.infer
[cloud-app]     ???
[cloud-app] pydantic/fields.py:342: in pydantic.fields.ModelField.__init__
[cloud-app]     ???
[cloud-app] pydantic/fields.py:456: in pydantic.fields.ModelField.prepare
[cloud-app]     ???
[cloud-app] pydantic/fields.py:670: in pydantic.fields.ModelField.populate_validators
[cloud-app]     ???
[cloud-app] pydantic/validators.py:710: in find_validators
[cloud-app]     ???
[cloud-app] E   RuntimeError: error checking inheritance of <strawberry.custom_scalar.ScalarWrapper object at 0x7ff0045537f0> (type: ScalarWrapper)

Additionally when I try to use pydantic.Json or pydantic.JsonWrapper I get an UnsupportedTypeError thrown, which is obvious from reading the code:

https://github.com/strawberry-graphql/strawberry/blob/main/strawberry/experimental/pydantic/fields.py#L42-L43

Maybe it will be obvious to someone what I'm doing wrong here?

Refs

• Custom scalars docs
• dict is not considered a type?