[BUG] Python client: response parsing fails for array of anyOf items

[hleb-albau]

Bug Report Checklist

• [] Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used? latest master
• Have you search for related issues/PRs?
• What's the actual output vs expected output? error during result parsing from server
• [Optional] Bounty to sponsor the fix (example)

Description

If openapi definition contains model of type array with anyOf items description, generated Python client can't parse request from server. Generated model has openapi_types with next type list[AnyOfFirstSecondThird]. During response parsing client takes one by one list items and try to de-serialize to non existing type klass AnyOfFirstSecondThird. Parsing fails at klass = getattr(openapi_client.models, klass) line with next error - module 'openapi_client.models' has no attribute 'AnyOfFirstSecondThird'

openapi-generator version

latest master, 5.0.0-SNAPSHOT

OpenAPI declaration file content or url

    ContainerList:
       type: array
       items:
         anyOf:
           - $ref: "#/components/schemas/FirstResultType"
           - $ref: "#/components/schemas/SecondResultType"
           - $ref: "#/components/schemas/ThirdResultType"

Command line used for generation

docker run --rm -v "${PWD}:/local" openapitools/openapi-generator-cli generate -i /local/docs/openapi.yml -g python -o /local/clients/python

Steps to reproduce

Related issues/PRs

Suggest a fix

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[spacether]

@hleb-albau have you tried using the python-experimental generator?
The python generator does not fully implement composed schemas but the python-experimentalgenerator does.
You can see tests of the anyOf class gmFruit here
That class is defined here
and is defined as:

    gmFruit:
       properties:
          color:
             type: string
       anyOf:
          - $ref: '#/components/schemas/apple'
          - $ref: '#/components/schemas/banana'
       additionalProperties: false

[hleb-albau]

@spacether
I tried to use python-experimental and got same results, but with slight different error - KeyError sys.modules[model.any_of_first_second_third']. And of course, model package does not contain any_of_first_second_third.
Also, the problem not directly related to case tested by gmFruit , but rather combination of array and it's type definition.

Btw, I tried online swagger editor and generate another version on client. Seems it is generated by swagger-generator. Using that client I get lucky with response parsing. But in the middle of de-serialization anyOf types were lost and replaces by raw dict.

I should prepare some full example, need some time.

[spacether]

Ah, I was missing that this was an array model. I though that it was an object type model. Can you provide the referenced anyOf models?

• FirstResultType
• SeconResultType
• ThirdResultType

We don't yet have code coverage of this use case in python-experimental.

[spacether]

In the short term, you could make an anyOf model which contains your anyOf definition. Then in your array model, just $ref to your new anyof model. That should work in python-experimental.

We also had a PR that just landed which creates arrayModels in python-experimental so

• you will no longer get the import error
• but your example may or may not work, not sure if our array model PR fixes your use case

[spacether]

This issue's root cause is that inline composed schemas are not handled by generators at this time.
Our tooling assumes that composed schemas are defined in components.
A more general solution is to add composed schema CodegenProperties and have generators use that inline definition.
These issues have the same root cause:

• [BUG][python-experimental] generation of oneOf interfaces not working for oneOf usage in properties - leads to import error #6161
• [BUG] OpenAPI 4.0.2 not able to generate anyOf models. #4576
• [BUG] Using allOf and $ref generates an object in the python model when it should be a string #8457
• [BUG] [C#] Polymorphism with 2 level derived classes generates invalid client #8849
• [cpp-restbed] items of oneOf and anyOf result in faulty code #4239
• [BUG] Generator try to use oneOf* model but does not create it #8860
• [BUG][Python] allOff not supported when used in array, in object #1657

In this proof of concept PR I show how we can add composed schema info to:
CodegenModel/CodegenProperty/CodegenParameter/CodegenResponse and then we can define these composed schemas at any level in generated code.
#8325
See this working in ComposedOneOfDifferentTypes here and see tests of it here

[spacether]

This work in python-experimental
One can see anyOf endpoints here: https://github.com/OpenAPITools/openapi-generator/blob/master/samples/openapi3/client/3_0_3_unit_test/python-experimental/docs/apis/tags/AnyOfApi.md
And anof model tests here: https://github.com/OpenAPITools/openapi-generator/blob/master/samples/openapi3/client/3_0_3_unit_test/python-experimental/test/test_models/test_anyof_complex_types.py
Which are passing in CI in node 4

[spacether]

python-experimental became the default python client in v6.2.0
If you upgrade your python client to that version, this feature will work for you