[R] avoid to-JSON issues when R6 classes contain lists of R6 classes

[mattpollock]

@Ramanth, @saigiridhar21, @wing328

This is a follow-up to #22697.

In #22697 I improved handling for deserializing cases where there is a list of R6 objects nested in a field of a parent R6 object. This PR handles converting an R6 object back to text (e.g., for printing to the console or generating a JSON representation of the object). Existing code did not properly handle the case and would throw an error when $toSimpleType() was invoked on x when x was a list (of R6 objects). This PR will recursively delve into the fields of an R6 object and invoke $toSimpleType() on nested R6 objects only after ensuring an object is an R6 object.

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---

Summary by cubic

Fixes JSON serialization in the R client when models contain nested lists/maps of R6 objects. Adds a recursive extractor so only R6 instances call toSimpleType, preventing errors when printing or generating JSON.

• Bug Fixes

  • Added extractSimpleType and hasNestedR6 to recursively handle nested R6 structures.
  • Updated the R model template to use extractSimpleType for arrays, maps, and single object fields.
  • Regenerated R samples (echo_api, petstore) to include the fix.
  • Follow-up to [R] fix set[object] deserialization #22697, extending the deserialization fix to serialization.

• Refactors

  • Only generate extractor methods when models have non-primitive fields.

^{Written for commit 9327b21. Summary will update on new commits.}

[cubic-dev-ai]

14 issues found across 75 files

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them.


<file name="samples/client/petstore/R-httr2-wrapper/R/pet_map.R">

<violation number="1" location="samples/client/petstore/R-httr2-wrapper/R/pet_map.R:84">
P2: Recursive conversion helpers are added but never used; additional_properties still serialized as raw R6 objects so nested R6 values remain unconverted.</violation>
</file>

<file name="samples/client/petstore/R-httr2-wrapper/R/dummy_model.R">

<violation number="1" location="samples/client/petstore/R-httr2-wrapper/R/dummy_model.R:85">
P2: Added nested-R6 helper is never used, so toSimpleType()/toJSONString still pass nested R6 values through unchanged and the intended serialization fix is not applied.</violation>
</file>

<file name="samples/client/petstore/R-httr2-wrapper/R/basque_pig.R">

<violation number="1" location="samples/client/petstore/R-httr2-wrapper/R/basque_pig.R:98">
P2: New nested-R6 helper added but never used; additional_properties still serialize raw R6 objects and can fail JSON conversion</violation>
</file>

<file name="samples/client/petstore/R/R/zebra.R">

<violation number="1" location="samples/client/petstore/R/R/zebra.R:101">
P2: Added nested-R6 conversion helper is unused; nested R6 values in additional_properties are still passed directly to jsonlite::toJSON, leaving serialization failures unresolved.</violation>
</file>

<file name="samples/client/petstore/R-httr2-wrapper/R/allof_tag_api_response.R">

<violation number="1" location="samples/client/petstore/R-httr2-wrapper/R/allof_tag_api_response.R:137">
P2: extractSimpleType/hasNestedR6 were added but never used by toSimpleType() or toJSONString(), so additional_properties are still serialized without conversion and nested R6 values remain unhandled.</violation>
</file>

<file name="samples/client/petstore/R/R/dog.R">

<violation number="1" location="samples/client/petstore/R/R/dog.R:112">
P2: Nested R6 conversion helpers are unused, so toJSON still receives raw R6 objects and may fail for additional_properties</violation>
</file>

<file name="samples/client/petstore/R-httr2-wrapper/R/animal.R">

<violation number="1" location="samples/client/petstore/R-httr2-wrapper/R/animal.R:100">
P2: New nested-R6 conversion helper is added but never used; additional_properties still pass raw R6 objects to jsonlite::toJSON, defeating the intended nested-R6 fix.</violation>
</file>

<file name="samples/client/petstore/R/R/whale.R">

<violation number="1" location="samples/client/petstore/R/R/whale.R:111">
P2: New nested-R6 helpers are added but never used; `toSimpleType()`/`toJSONString()` still emit raw `additional_properties`, so nested R6 objects remain unconverted and the intended JSON fix is ineffective.</violation>
</file>

<file name="samples/client/petstore/R/R/date.R">

<violation number="1" location="samples/client/petstore/R/R/date.R:115">
P2: New nested-R6 conversion helper is unused; additional_properties still pass R6 values straight to jsonlite::toJSON, so nested R6 in additional properties will still fail serialization and the helper becomes dead code.</violation>
</file>

<file name="samples/client/petstore/R-httr2-wrapper/R/format_test.R">

<violation number="1" location="samples/client/petstore/R-httr2-wrapper/R/format_test.R:258">
P2: New nested-R6 conversion helpers are added but never invoked by `toSimpleType()`/`toJSONString()`, so nested R6 values are still serialized raw and the intended JSON fix isn’t applied in this class.</violation>
</file>

<file name="samples/client/petstore/R/R/special.R">

<violation number="1" location="samples/client/petstore/R/R/special.R:165">
P2: Added extractSimpleType()/hasNestedR6 helpers are never invoked in Special, so serialization still copies additional_properties verbatim and the new recursive conversion logic is unused.</violation>
</file>

<file name="modules/openapi-generator/src/main/resources/r/modelGeneric.mustache">

<violation number="1" location="modules/openapi-generator/src/main/resources/r/modelGeneric.mustache:276">
P2: New public method names can collide with schema property names, causing field/method overwrite in generated R6 models when a schema property is named `extractSimpleType` or `hasNestedR6`.</violation>
</file>

<file name="samples/client/petstore/R/R/model_api_response.R">

<violation number="1" location="samples/client/petstore/R/R/model_api_response.R:111">
P2: `extractSimpleType()`/`hasNestedR6()` are added but never used by `toSimpleType()`/`toJSONString()`, so nested R6 values still reach `jsonlite::toJSON()` unconverted. The new helpers are effectively dead code and do not address the to-JSON issue.</violation>
</file>

<file name="samples/client/petstore/R-httr2-wrapper/R/cat.R">

<violation number="1" location="samples/client/petstore/R-httr2-wrapper/R/cat.R:112">
P2: New nested-R6 conversion helpers are never used in Cat serialization methods, so additional_properties are still passed through unchanged and the added helper has no effect.</violation>
</file>

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[wing328]

thanks for the PR

let's give it a try