Handling of nullable for $ref in OpenAPI 3.0

[bluenote10]

I have an API that needs to differentiate between properties that are T | null and T | undefined. It looks like using nullable works for basic types but is ignored for $ref:

schemas:
  TestObject:
    type: object
    properties:
      stringMaybeUndefined:
        type: string
      stringMaybeNullA:
        type: string
        nullable: true
      stringMaybeNullB:
        anyOf:
        - type: string
        nullable: true
      otherObjectMaybeUndefined:
        $ref: "#/components/schemas/OtherObject"
      otherObjectMaybeNullA:
        $ref: "#/components/schemas/OtherObject"
        nullable: true
      otherObjectMaybeNullB:
        anyOf:
        - $ref: "#/components/schemas/OtherObject"
        nullable: true
    required:
    - stringMaybeNullA
    - stringMaybeNullB
    - otherObjectMaybeNullA
    - otherObjectMaybeNullB

  OtherObject:
    type: object

Generates:

export interface TestObject {
  stringMaybeUndefined?: string;
  stringMaybeNullA?: string | null;
  stringMaybeNullB?: string;
  otherObjectMaybeUndefined?: OtherObject;
  otherObjectMaybeNullA?: OtherObject;
  otherObjectMaybeNullB?: OtherObject;
}

Note: The OpenAPI 3.1 syntax

oneOf:
- $ref: "#/components/schemas/OtherObject"
- type: 'null'

works, but I'm forced to use OpenAPI 3.0 because of constraints from other tooling.

Can this be achieved somehow?

Edit, relevant resources:

• Reference objects don't combine well with “nullable” OAI/OpenAPI-Specification#1368
• https://github.com/OAI/OpenAPI-Specification/blob/master/proposals/003_Clarify-Nullable.md

If I interpret these (long) discussions correctly, at least the allOf wrapping should work?

[js2me]

I know about this problem
nullable works not very well, I'll fix it today, probably I need 1 hour to fix that

With my local changes tool currently generates this TestObject

[bluenote10]

Looks good, thanks for the super fast maintenance!

[js2me]

@bluenote10 currently I have problem with parsing this case

        otherObjectMaybeNullD:
          anyOf:
          - $ref: "#/components/schemas/OtherObject"
          - type: 'null'

I guess it should be like

otherObjectMaybeNullD: OtherObject | null;

[bluenote10]

Yes combining null in anyOf is a bit awkward, because in this case there cannot be multiple matches. I agree that handling it identical to oneOf makes the most sense.

[js2me]

I think I covered most cases with usage nullable option.
Schema:
https://github.com/acacode/swagger-typescript-api/blob/796d1cc7f8fc9a554e30a06b0d6512fd72444b3d/tests/schemas/v3.0/nullable-refs.yaml
Generated ouput:
https://github.com/acacode/swagger-typescript-api/blob/796d1cc7f8fc9a554e30a06b0d6512fd72444b3d/tests/generated/v3.0/nullable-refs.ts

[js2me]

Should be fixed in release 1.6.3
If someone still have same problems, please reopen issue and attach part of swagger schema

[Akimyou]

I think I covered most cases with usage nullable option. Schema: https://github.com/acacode/swagger-typescript-api/blob/796d1cc7f8fc9a554e30a06b0d6512fd72444b3d/tests/schemas/v3.0/nullable-refs.yaml Generated ouput: https://github.com/acacode/swagger-typescript-api/blob/796d1cc7f8fc9a554e30a06b0d6512fd72444b3d/tests/generated/v3.0/nullable-refs.ts

can you handle this part?

                      "oneOf": [
                        {
                          "$ref": "#/definitions/348",
                          "x-apifox-overrides": {}
                        },
                        {
                          "type": "null"
                        }
                      ],