[BUG] [python] Discriminator imports are wrong

[OliverTetzTT]

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

When generating a python client using the current release of the openapi generator, the discriminator class imports are wrong.

(To get to this point, I already fixed the circular import by moving the petstore.models.pet import Pet line to the top of the import block in __init__.py files in the apiclient and models packages. (Can be automated by isort's force_to_top option. And is therefore currently fixable in an automated way. So not perfect but fixable for now))

pytest results in:

api-clients/testing/test/test_cat.py:None (api-clients/testing/test/test_cat.py)
ImportError while importing test module '***\api-clients\testing\test\test_cat.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
***\pypoetry\Cache\virtualenvs\petstore-NEbAbLrb-py3.11\Lib\site-packages\_pytest\python.py:617: in _importtestmodule
    mod = import_path(self.path, mode=importmode, root=self.config.rootpath)
***\pypoetry\Cache\virtualenvs\petstore-NEbAbLrb-py3.11\Lib\site-packages\_pytest\pathlib.py:567: in import_path
    importlib.import_module(module_name)
***\Lib\importlib\__init__.py:126: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
<frozen importlib._bootstrap>:1206: in _gcd_import
    ???
<frozen importlib._bootstrap>:1178: in _find_and_load
    ???
<frozen importlib._bootstrap>:1149: in _find_and_load_unlocked
    ???
<frozen importlib._bootstrap>:690: in _load_unlocked
    ???
***\Cache\virtualenvs\petstore-NEbAbLrb-py3.11\Lib\site-packages\_pytest\assertion\rewrite.py:178: in exec_module
    exec(co, module.__dict__)
test_cat.py:18: in <module>
    from petstore.models.cat import Cat  # noqa: E501
..\petstore\__init__.py:20: in <module>
    from petstore.api.default_api import DefaultApi
..\petstore\api\__init__.py:4: in <module>
    from petstore.api.default_api import DefaultApi
..\petstore\api\default_api.py:22: in <module>
    from petstore.models.catkiller import Catkiller
..\petstore\models\__init__.py:17: in <module>
    from petstore.models.pet import Pet
..\petstore\models\pet.py:106: in <module>
    from petstore.models.dog import dog
E   ModuleNotFoundError: No module named 'petstore.models.dog'

This is because the generated file for Pet looks like this (shortened):

# shortened header for bug ticket

class Pet(BaseModel):
    """
    Pet
    """
    pet_type: StrictStr = Field(alias="petType")
    __properties: ClassVar[List[str]] = ["petType"]

    model_config = {
        "populate_by_name": True,
        "validate_assignment": True
    }


    # JSON field name that stores the object type
    __discriminator_property_name: ClassVar[List[str]] = 'petType'

    # discriminator mappings
    __discriminator_value_class_map: ClassVar[Dict[str, str]] = {
        'dog': 'Catkiller','Cat': 'Cat','Lizard': 'Lizard'   # <--- here the mapping states that dog should be mapped to Catkiller
    }

# shortened class for bug ticket

from petstore.models.cat import Cat
from petstore.models.dog import dog  # <--- this line is the problem. It should import Catkiller instead of Dog here
from petstore.models.lizard import Lizard
from typing import TYPE_CHECKING
if TYPE_CHECKING:
    # TODO: pydantic v2
    # Pet.model_rebuild()
    pass

The problem line at the bottom should be:

from petstore.models.catkiller import Catkiller

After that all tests are successful

openapi-generator version

docker run --rm -v .:/local openapitools/openapi-generator-cli --version                                                                                                                                                     
openapi-generator-cli 7.1.0-SNAPSHOT
  commit : 1fc0cec
  built  : -999999999-01-01T00:00:00+18:00
  source : https://github.com/openapitools/openapi-generator
  docs   : https://openapi-generator.tech/

OpenAPI declaration file content

openapi: 3.0.0
info:
  title: Test Inheritance
  version: 1.0.0
servers:
  - url: /
paths:
  /test:
    get:
      operationId: test
      requestBody:
        content:
          application/json:
            schema:
              $ref: "#/components/schemas/Catkiller"
        required: true
      responses:
        "200":
          description: Success
        default:
          description: Unexpected Error

components:
  schemas:
    Pet:
      type: object
      required:
        - petType
      properties:
        petType:
          type: string
      discriminator:
        propertyName: petType
        mapping:
          dog: '#/components/schemas/Catkiller'
    Cat:
      allOf:
        - $ref: '#/components/schemas/Pet'
        - type: object
          properties:
            name:
              type: string
    Catkiller:
      allOf:
        - $ref: '#/components/schemas/Pet'
        - type: object
          properties:
            bark:
              type: string
    Lizard:
      allOf:
        - $ref: '#/components/schemas/Pet'
        - type: object
          properties:
            lovesRocks:
              type: boolean

Generation Details

docker run --rm -v .:/local openapitools/openapi-generator-cli generate -i /local/testing.yaml -g python -o /local/api-clients/testing --additional-properties=packageName=petstore

Steps to reproduce

1. Generate python client
2. CD to folder of client
3. Run poetry install
4. Fix circle import by moving Pet import to the top in __init__.py files
5. run pytest .

Related issues/PRs

I could not find one.

[OliverTetzTT]

This was resolved in the linked Pull request.