[BUG][Ruby] Using oneOf generated code has unexpected results

[ssteeg-mdsol]

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?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Bounty to sponsor the fix (example)

Description

When a oneOf is used, the generated model only includes one of the possible classes. Using the client, objects for all class types are forced into the same class, even if they're a different class.

In the below example, if the API returns a AuthenticationMonitor MonitorResult object, the generated client forces it into the SmokeTestMonitor class type. This is a problem as it's the incorrect class type and as a result the model attributes are all nil.

Current output for the AuthenticationMonitor MonitorResult object:

...
@items=[#<ClientExample::SmokeTestResult:0x00007fb45220eaa0>]
...

Expected output for the AuthenticationMonitor MonitorResult object:

...
@items=[#<ClientExample::AuthenticationMonitorItems:0x00007fb45220eaa0 @result=true>]
...

openapi-generator version

4.1.0, seems to occur in every 4.x version. Haven't checked previous versions.

OpenAPI declaration file content or url

OpenAPI spec

AuthenticationMonitor and SmokeTestMonitor are the same but the property name inside items is different

openapi: 3.0.2
info:
  title: Example
  version: v1
paths:
  /endpoint:
    get:
      summary: Get All Monitors
      responses:
        '200':
          description: Successful operation.
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Monitor'
components:
  schemas:
    Monitor:
      type: object
      properties:
        results:
          $ref: '#/components/schemas/MonitorResults'
    MonitorResults:
      oneOf:
        - $ref: '#/components/schemas/AuthenticationMonitor'
        - $ref: '#/components/schemas/SmokeTestMonitor'
    AuthenticationMonitor:
      type: object
      properties:
        items:
          type: array
          items:
            type: object
            properties:
              result:
                type: boolean
    SmokeTestMonitor:
      type: object
      properties:
        items:
          type: array
          description: Collection of smoke test result checks.
          items:
            type: object
            properties:
              passed:
                type: boolean

Command line used for generation

openapi-generator generate -i <OPENAPI_SPEC> -g ruby -o <TEMP_DIR> -c <CONFIG_PATH>

Steps to reproduce

1. Run the command to generate the Ruby client
2. Look at the

Related issues/PRs

Maybe #15 is related, but this issue is more specific to the Ruby client.

Another issue related to oneOf for the Ruby client is the generation of objects within a response schema. If you have the following OpenAPI spec, the class type gets generated as ExampleClient::OneOfsimpleObjectcomplexObject, and that class does not exist.

OpenAPI spec snippet

Here is the spec:

paths:
  /endpoint:
    get:
      summary: Get All Monitors
      responses:
        '200':
          description: Successful operation.
          content:
            application/json:
              schema:
                oneOf:
                  - $ref: '#/components/schemas/simpleObject'
                  - $ref: '#/components/schemas/complexObject'

components:
  schemas:
    simpleObject:
      type: object
      properties:
        simple_property1:
          type: string
    complexObject:
      type: object
      properties:
        complex_property1:
          type: string
        complex_property2:
          type: string

Suggest a fix

In https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/ruby-client/partial_model_generic.mustache#L49, the generated client only includes one option Array<SmokeTestResult>. I'm not sure about a specific fix, but has there been any Ruby-specific development into this area?

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[autopp]

@ssteeg-mdsol Thank you for the report.
Does the following response reproduce this problem?

[
  {
    "results": {
      // AuthenticationMonitor
      "items": [
        {
          "result": true
        }
      ]
    }
  },
  {
    "results": {
      // SmokeTestMonitor
      "items": [
        {
          "passed": true
        }
      ]
    }
  }
]

[autopp]

@ssteeg-mdsol

Expected output for the AuthenticationMonitor MonitorResult object:

...
@items=[#<ClientExample::SmokeTestResult:0x00007fb45220eaa0 @result=true>]
...

And isn't the expected output in your description here?

...
@items=[#<ClientExample::AuthenticationMonitorItems:0x00007fb45220eaa0 @result=true>]
...

[autopp]

This is not just a problem for Ruby, but for example Python.
A Python client generated with the same input contains the following code in openapi_client/models/monitor_results.py:

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

    Do not edit the class manually.
    """

    """
    Attributes:
      openapi_types (dict): The key is attribute name
                            and the value is attribute type.
      attribute_map (dict): The key is attribute name
                            and the value is json key in definition.
    """
    openapi_types = {
        'items': 'list[SmokeTestMonitorItems]' # <- missing AuthenticationMonitorItems
    }

This looks like a problem with the Ruby client.
If there is the same field in the schema selected by oneOf (or AnyOf), only one of them will be reflected. (In this case, it is items)

[ssteeg-mdsol]

@autopp Sorry for the slow reply! My Gmail filters let me down 🙇 Thanks for taking a look at this issue!

You're right about the expected output, I will update the issue description.

I believe the response you provided should reproduce the problem but will double-check this afternoon.

[ssteeg-mdsol]

Confirmed that the response you provided reproduces the issue.

A response of

[
  {
    "results": {
      // AuthenticationMonitor
      "items": [
        {
          "result": true
        }
      ]
    }
  },
  {
    "results": {
      // SmokeTestMonitor
      "items": [
        {
          "passed": true
        }
      ]
    }
  }

results in the following (from the ruby console):

items[0].results.items
# => [#< ClientExample::SmokeTestResult:0x00007ff1261bb380>]
items[0].results.items.first.passed
# => nil
items[0].results.items.first.result
Traceback (most recent call last):
        1: from (irb):11
NoMethodError (undefined method `result` for #< ClientExample::SmokeTestResult:0x00007ff1261bb380>)
Did you mean?  rescue

items[1].results.items
# => [#< ClientExample::SmokeTestResult:0x00007f98f4b191f0 @passed=true>]
items[1].results.items.first.passed
# => true

[ssteeg-mdsol]

@autopp Do you have ideas about how or where the logic to handle oneOf could be implemented? Is there anything I can do to help fix the issues? Sorry for the vague questions, I'm not really sure where to start. 😕

[Frontrider]

It's a general issue with the generator. Java has the same issue, no fix has been provided so far.

[autopp]

@ssteeg-mdsol Sorry for the late reply.
As @Frontrider comments, this seems to be a general generator problem.
Unfortunately I still haven't been sure where to start.

[Frontrider]

my start was to look into the java generator code, and I found absolutely no support for it in the example generator. i think it is just unimplemented.

[jfeltesse-mdsol]

I tried to take a stab at it in #5706