[Python] Fix the post processing of enums

[0xMattijs]

description

This fixes the issue described in #16560 of a problem with the Python family of converters that when processing enums, none of them substitutes the enum var extensions.

When processing the following schema:

openapi: 3.0.0
info:
  version: 1.0.0
  title: Weather API
paths: {}

components:
  schemas:
    WeatherType:
      type: integer
      format: int32
      enum:
        - 42
        - 18
        - 56
      x-enum-descriptions:
        - 'Blue sky'
        - 'Slightly overcast'
        - 'Take an umbrella with you'
      x-enum-varnames:
        - Sunny
        - Cloudy
        - Rainy

The generator would yield:

from datetime import date, datetime  # noqa: F401

from typing import List, Dict  # noqa: F401

from openapi_server.models.base_model import Model
from openapi_server import util


class WeatherType(Model):
    """NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).

    Do not edit the class manually.
    """

    """
    allowed enum values
    """
    NUMBER_42 = 42
    NUMBER_18 = 18
    NUMBER_56 = 56
    def __init__(self):  # noqa: E501
        """WeatherType - a model defined in OpenAPI

        """
        self.openapi_types = {
        }

        self.attribute_map = {
        }

    @classmethod
    def from_dict(cls, dikt) -> 'WeatherType':
        """Returns the dict as a model

        :param dikt: A dict.
        :type: dict
        :return: The WeatherType of this WeatherType.  # noqa: E501
        :rtype: WeatherType
        """
        return util.deserialize_model(dikt, cls)

The variables have the default NUMBER_x substitutions.

problem

The problem is caused by the fact that the enum var extension substitutions done bypostProcessModelsEnum at the beginning of postProcessModelsMap are overwritten at a later point in that same method.

openapi-generator/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractPythonCodegen.java

Line 868 in 296a6ac

private ModelsMap postProcessModelsMap(ModelsMap objs) {

The overwriting of the variable names occurs here:

https://github.com/OpenAPITools/openapi-generator/blob/296a6ac5163b226015511b4bea42b78f0d2966f3/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractPythonCodegen.java#L986C10-L998C14

Note: the proposed solution mentioned in #16560 of calling postProcessModelsEnum as part of postProcessModels seems ineffective, as the override postProcessModels is never called by the generator.

proposed solution

Add a condition to test if x-enum-varnames exist before performing the default NUMBER_x substition.

A previous attempt to fix the issue by moving postProcessModelsEnum to the end of the method lead to a complication with string enum types, ending up with variable names ending up enclosed in double quotes.

With the proposed modification the generated is as expected:

class WeatherType(Model):
    """NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).

    Do not edit the class manually.
    """

    """
    allowed enum values
    """
    Sunny = 42
    Cloudy = 18
    Rainy = 56
    def __init__(self):  # noqa: E501
        """WeatherType - a model defined in OpenAPI

        """
        self.openapi_types = {
        }

        self.attribute_map = {
        }

checklist

• Read the contribution guidelines.
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  ./mvnw clean package 
  ./bin/generate-samples.sh ./bin/configs/*.yaml
  ./bin/utils/export_docs_generators.sh
  

  (For Windows users, please run the script in Git BASH)
  Commit all changed files.
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[0xMattijs]

It turns out there are still some complications with this PR, as moving the postProcessModelsEnum will cause the generator to emit faulty variable names for string enums:

E.g.:

 class OuterEnum(str, Enum):
     """
     allowed enum values
     """

    'placed' = 'placed'
    'approved' = 'approved'
    'delivered' = 'delivered'

Expected:

class OuterEnum(str, Enum):
     """
     allowed enum values
     """
     PLACED = 'placed'
     APPROVED = 'approved'
     DELIVERED = 'delivered'

[0xMattijs]

Since the desired enum post processor is run before all other transformations in the Python generator, a working approach is to prevent the enum transformation for int enums to run if the x-enum-varnames vendorExtensions is present.

[wing328]

thanks for the PR. can you please add a test spec to modules/openapi-generator/src/test/resources/3_0/python/petstore-with-fake-endpoints-models-for-testing.yaml ?

[0xMattijs]

@wing328 I have added the definitions below to petstore-with-fake-endpoints-models-for-testing.yaml and I have executed bin/generate-samples.sh.

Is there anything else I need to do, like defining the expected results somewhere?

        enum_number_vendor_ext:
          type: integer
          format: int32
          enum:
            - 42
            - 18
            - 56
          x-enum-descriptions:
            - 'Description for 42'
            - 'Description for 18'
            - 'Description for 56'
          x-enum-varnames:
            - FortyTwo
            - Eigtheen
            - FiftySix
        enum_string_vendor_ext:
          type: string
          enum:
            - FOO
            - Bar
            - baz
          x-enum-descriptions:
            - 'Description for FOO'
            - 'Description for Bar'
            - 'Description for baz'
          x-enum-varnames:
            - FOOVar
            - BarVar
            - bazVar

[wing328]

thanks for the PR, which has been merged.

have a nice weekend