[BUG][Python] OneOf creates a pydantic Field which is not support in pydantic v2 const=True

[bykof]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?

Description

If I create a schema that has a oneOf or anyOf field, it generates a pydantic Field with const=True.
The keyword const=True is deprecated and removed in pydantic v2.
The error is: PydanticUserError('constis removed, useLiteral instead'

openapi-generator version

v6.6.0

OpenAPI declaration file content or url

openapi: 3.0.3
servers:
  - url: https://petstore3.swagger.io/api/v3
paths:
  /pets:
    patch:
      requestBody:
        content:
          application/json:
            schema:
              oneOf:
                - $ref: '#/components/schemas/Cat'
                - $ref: '#/components/schemas/Dog'
      responses:
        '200':
          description: Updated
components:
  schemas:
    Dog:
      type: object
      properties:
        bark:
          type: boolean
        breed:
          type: string
          enum: [Dingo, Husky, Retriever, Shepherd]
    Cat:
      type: object
      properties:
        hunts:
          type: boolean
        age:
          type: integer

Generation Details

docker run --rm -v ${PWD}:/local openapitools/openapi-generator-cli generate -g python --additional-properties=generateSourceCodeOnly=true,packageName=client --skip-validate-spec -o /local/ -i /local/openapi.yaml

Suggest a fix

Change to Literal instead of using Field(..., const=True)

[fa0311]

This issue has been fixed.
#15189

[lvijnck]

@fa0311 @wing328 how to use this version? I am using the latest version of the CLI, i.e., latest. Should this not use the right version of the generation? My local build is still failing on this.

[fa0311]

how to use this version? I am using the latest version of the CLI, i.e., latest. Should this not use the right version of the generation? My local build is still failing on this.

Update dependencies.

pydantic==1.10.12

[lvijnck]

@fa0311 The produced code still contains Field(..., const=True) as opposed to Literal. I have updated my dependencies.

[fa0311]

@lvijnck

The produced code still contains Field(..., const=True) as opposed to Literal.

Yes. The generated code contains Field(..., const=True)
PydanticUserError error can be avoided by setting the pydantic v2.

The current openapi-generator Python generator does not support pydantic v3.

[lvijnck]

@fa0311 Error is still there for me.

 raise PydanticUserError('`const` is removed, use `Literal` instead', code='removed-kwargs')
 pydantic.errors.PydanticUserError: `const` is removed, use `Literal` instead

Using:

pydantic==2.2.1

Or do you mean it does not work with Pydantic v2?

And the following code to produce my source code:

docker run --rm \
    -v "${PWD}:/src" openapitools/openapi-generator-cli:latest generate \
    -i /src/asset-service/openapi/core-api.json \
    -g python \
    -o /src/asset-service/src \
    --additional-properties=generateSourceCodeOnly=true,packageName=core_api,library=asyncio

Happy to share my specs as needed. For now, I just removed the following line from the generated source code and committed it to my repo, which feels like a mess.

one_of_schemas: List[str] = Field(.., const=True)

Why is this field added anyway? It does not seem to be used?

Thanks for the response!

[fa0311]

@lvijnck

PydanticUserError error can be avoided by setting the pydantic v2.

The current openapi-generator Python generator does not support pydantic v3

This was my typo, actually v2 was a mistake for v1 and v3 was a mistake for v2.

Or do you mean it does not work with Pydantic v2?

Exactly, use v1 as v2 is not supported.

[lvijnck]

I just bumped my entire API to Python 3.11 so I'd rather not go back. I will have some capacity end of month to contribute back to the generators. So will be in touch. Thanks!

[oshmoun]

I just bumped my entire API to Python 3.11 so I'd rather not go back. I will have some capacity end of month to contribute back to the generators. So will be in touch. Thanks!

I have an example of how such an update would look like in #16469, if you would like to take a look

[lvijnck]

Why is this closed?