[BUG][Python] Multi-level inheritance not working correctly

Created by: tomghyselinck

Description

The generated Python client does not properly return the final classes when multi-level inheritance is used.

For example:

When GET /pet returns any of AngryDog, NiceDog, and FunnyCat object, the Python client will return a Pet object (without all final_type-specific attributes missing).
When GET /dog returns any of AngryDog or NiceDog object, the Python client will return a Pet object (without all final_type-specific attributes missing).

Please note that you can also see that the member fields of the Pet and Dog parent object are missing in the AngryDog (cfr. #453 (closed)).

openapi-generator version

I used OpenAPI generator CLI version 4.0.0-SNAPSHOT: https://oss.sonatype.org/content/repositories/snapshots/org/openapitools/openapi-generator-cli/4.0.0-SNAPSHOT/openapi-generator-cli-4.0.0-20181210.103357-85.jar

OpenAPI declaration file content or url

See multi-level-inheritance.yaml in the attached zip-file: multi-level-inheritance.zip

Command line used for generation

java -jar openapi-generator-cli-4.x.jar generate -i ./multi-level-inheritance.yaml -g python -o ./multi-level-inheritance/client/python

Steps to reproduce

Generate client code

See also multi-level-inheritance.sh.

wget \
    'https://oss.sonatype.org/content/repositories/snapshots/org/openapitools/openapi-generator-cli/4.0.0-SNAPSHOT/openapi-generator-cli-4.0.0-20181210.103357-85.jar' \
    -O 'openapi-generator-cli-4.x.jar'
rm -rf ./multi-level-inheritance/
java -jar openapi-generator-cli-4.x.jar generate -i ./multi-level-inheritance.yaml -g python -o ./multi-level-inheritance/client/python

Start (mocked) server

python3 -m connexion run --mock=all multi-level-inheritance.yaml

Run the client test

(cd multi-level-inheritance/client/python/ && python3)

import openapi_client
api = openapi_client.DefaultApi()
pet = api.pet_get()
print(type(pet))
print(pet)
dog = api.dog_get()
print(type(dog))
print(dog)

Output:

<class 'openapi_client.models.pet.Pet'>
{'pet_type': 'NiceDog'}
<class 'openapi_client.models.dog.Dog'>
{'doggie_thing': 'Playing with piece of wood'}

Related issues/PRs

#1842
#1841

Similar issues has been seen with CSHARP and Java:

Suggest a fix

When we add an addition discriminator in the Dog schema then GET /dog does properly return either an AngryDog or NiceDog object.