Not sure what the relnotes tag should be. I did relnotes-change since it's arguably not a bugfix but not sure what's best.

CodSpeed Performance Report

Merging #8944 will not alter performance

_{Comparing dmontagu/add-enum-to-json-schema-single-item-literal (02ab56d) with main (af41c8e)}

Summary

✅ 10 untouched benchmarks

After updating to 2.7 we issued a problem with generating frontend api for schema

We have some objects, specified by discriminator:

class ProfileBase(BaseModel):
    guid: str
    model_type: str


class ProfileFoo(ProfileBase):
    model_type: Literal["FOO"]
    # some foo specific fields


class ProfileBar(ProfileBase):
    model_type: Literal["BAR"]
    # some bar specific fields


Profile = Annotated[
    Union[ProfileFoo, ProfileBar],
    Field(discriminator="model_type")
]


router = APIRouter(prefix="/profiles")


@router.get("/")
def list_profiles() -> list[Profile]:
    return []

On frontend swagger-typescript-api is used for code generation
https://github.com/acacode/swagger-typescript-api

Here is exampe of generated code:

/** Model Type */
export enum ProfileFooModelTypeEnum {
  FOO = 'FOO',
}

/** ProfileFoo */
export interface ProfileFoo {
  /** Guid */
  guid: string;
  /** Model Type */
  model_type: ProfileFooModelTypeEnum;
  // For pydantic<2.7 it was like this:
  // model_type: 'FOO';
}


// here is generated api request
// discrimitator field is string, but object field is enum 
listProfiles: (params: RequestParams = {}) =>
      this.request<
        (
          | ({
              model_type: 'FOO';
            } & ProfileFoo)
          | ({
              model_type: 'BAR';
            } & ProfileBar)
        )[],
        AppExceptionSchema
      >({
        path: `/profiles/`,
        method: 'GET',
        secure: true,
        format: 'json',
        ...params,
      }),

For generated api there is a type mismatch, because discriminator field is string and object field is enum.

This looks like a bug. Can we remove enum field for Literal with one value, or at least add some flag for this option?

Hi @fi11er,

Thanks for the report - please open another issue with said description and we'll be sure to take a look!