[BUG][PYTHON] Failed to lookup discriminator value using AllOf and discriminator

[zishunwei]

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?
  expected output: Calling for the DefaultApi.get_user_info() passes
  actual output:

ValueError: Base failed to lookup discriminator value from {"_typeName": "string", "_value": "some string"}. Discriminator property name: _typeName, mapping: {"string": "PrimitiveString", "Info": "Info"}

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Description

Although I have a mapping "string": "PrimitiveString", but still failed to lookup discriminator value from {"_typeName": "string", "_value": "some string"}.

The root cause is there is a bug to get the object_type in in the from_dict of base model, it should be "string" instead of "PrimitiveString", causing the failure of mapping.

This is from_dict of base model generated:

    @classmethod
    def from_dict(cls, obj: Dict[str, Any]) -> Optional[Union[PrimitiveString, Info]]:
        """Create an instance of Base from a dict"""
        # look up the object type based on discriminator mapping
        object_type = cls.get_discriminator_value(obj)
        if object_type ==  'string':
            return import_module("openapi_client.models.primitive_string").PrimitiveString.from_dict(obj)
        if object_type ==  'Info':
            return import_module("openapi_client.models.info").Info.from_dict(obj)

        raise ValueError("Base failed to lookup discriminator value from " +
                            json.dumps(obj) + ". Discriminator property name: " + cls.__discriminator_property_name +
                            ", mapping: " + json.dumps(cls.__discriminator_value_class_map))

openapi-generator version

Latest master code 25/04/2024

OpenAPI declaration file content or url

openapi: 3.0.0
info:
  title: ""
  version: ""
paths:
  /user/getInfo:
    get:
      operationId: getUserInfo
      responses:
        "200":
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Info'
          description: |
            OK
      security:
        - Session: []
      x-accepts: application/json
components:
  schemas:
    Info:
      allOf:
        - $ref: '#/components/schemas/Base'
      example:
        val:
          _typeName: _typeName
      properties:
        val:
          $ref: '#/components/schemas/Base'
      required:
        - val
      type: object
    Base:
      discriminator:
        mapping:
          string: '#/components/schemas/PrimitiveString'
        propertyName: _typeName
      properties:
        _typeName:
          type: string
      required:
        - _typeName
      type: object
    PrimitiveString:
      allOf:
        - $ref: '#/components/schemas/Base'
      properties:
        _value:
          type: string
      required:
        - _value
      type: object

Generation Details

Enable REFACTOR_ALLOF_WITH_PROPERTIES_ONLY=true

java -jar modules/openapi-generator-cli/target/openapi-generator-cli.jar generate -i disc.yaml -g python -o disc --openapi-normalizer REFACTOR_ALLOF_WITH_PROPERTIES_ONLY=true

Steps to reproduce

1. run a server to response like:
   {
   "_typeName": "Info",
   "val": {
   "_typeName": "string",
   "_value": "some string"
   }
   }

2. call get_user_info() API

Related issues/PRs

Suggest a fix

When generating the discriminator model, should have some fix to make the mapping available.