Work with optional schema and route parameters

[aptypr]

Hello!
I'm trying to move my project to Pydantic 2, but still keep OpenAPI 3.0 swagger

I generate swagger with code like

raw = get_openapi(
      title=app.title,
      version=app.version,
      routes=app.routes,
  )
raw.pop("openapi", None)
raw_schema = raw


openapi_obj = raw_schema
openapi_obj = OpenAPI.model_validate(openapi_obj, strict=False)
openapi_obj = construct_open_api_with_schema_class(openapi_obj)
openapi_obj.model_dump_json(by_alias=True, exclude_none=True, indent=2)

and I get a lot of errors for optional field in schemas and routes
for example for something like

class A(BaseModel):
    start: Optional[float] = Field(default=None, title="start")
    stop: Optional[float] = Field(default=None, title="end")

I get error like

components.schemas.A.Schema.properties.stop.Schema.anyOf.1.Schema.type
Input should be 'string', 'number', 'integer', 'boolean', 'array' or 'object' [type=enum, input_value='null', input_type=str]

and similar error for handlers, for optional parameters.
I can make there errors disappear, replacing Optional[T] with Union[T, SkipJsonSchema[None]], but I have a lot of schemas and routes to change.

Maybe I do something wrong?

[mike-oakley]

Hey @aptypr - thanks for reaching out!

Are you importing the above from the OpenAPI 3.0 module? This has a compatibility layer built in which handles some of the differences between 3.0 and 3.1 - for example:

from openapi_pydantic.v3.v3_0 import OpenAPI
from openapi_pydantic.v3.v3_0.util import construct_open_api_with_schema_class

openapi_obj = OpenAPI.model_validate(raw_schema, strict=False)
openapi_obj = construct_open_api_with_schema_class(openapi_obj)
print(openapi_obj.model_dump_json(by_alias=True, exclude_none=True, indent=2))

[aptypr]

Yes, I imported compatibility layer

from fastapi.openapi.models import OpenAPI
from fastapi.openapi.utils import get_openapi
from openapi_pydantic.v3.v3_0 import  OpenAPI
from openapi_pydantic.v3.v3_0.util import PydanticSchema, construct_open_api_with_schema_class

[mike-oakley]

I believe the output of the FastAPI get_openapi output defaults to 3.1.0 in modern versions - is the output of that function definitely giving an OpenAPI 3.0.x formatted schema?

If you use the openapi_pydantic.parse_obj function provided at the root of the library, it will automatically infer the OpenAPI schema version (but obviously you may then have to deal with the differences in the format in your downstream code).

[aptypr]

You are correct, I'm using fastapi 0.115.12, and get_openapi return 3.1.0 version.
I want the output to be 3.0 specification and thought that import from openapi_pydantic.v3.v3_0 is exactly for this.