OpenAPITools / OpenAPITools/openapi-generator

[BUG][KOTLIN] Number-based enums with defaults result in invalid Kotlin enums

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Issue: Bug
Dominant language
Java
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Description

Bug Report Checklist
  • Have you provided a full/minimal spec to reproduce the issue?
  • Have you validated the input using an OpenAPI validator?
  • Have you tested with the latest master to confirm the issue still exists?
  • Have you searched for related issues/PRs?
  • What's the actual output vs expected output?
  • [Optional] Sponsorship to speed up the bug fix or feature request (example)
Description

Number-based enums with defaults result in invalid Kotlin enums. With no options, enums are generated like this:

 enum class OwnedByYouGetArchivedDeals(val value: java.math.BigDecimal) {
        @JsonProperty(value = ""0"") _0("0"),
        @JsonProperty(value = ""1"") _1("1")
    }

After adding number=kotlin.Int as a type mapping, the resulting enum is fine, but the instantiations of non-null default values are still broken:

enum class IsActive(val value: kotlin.Int) {
        @JsonProperty(value = "0") _0(0),
        @JsonProperty(value = "1") _1(1);
    }

val isActive: BaseWebhook.IsActive? = kotlin.Int("IsActive._1"),
openapi-generator version

I use the latest version of the Maven plugin (openapi-generator-maven-plugin, version 7.20.0).

OpenAPI declaration file content or url

Number-based boolean enums, with a default value:

                - in: query
                  name: skip_users
                  schema:
                      title: numberBooleanDefault0
                      type: number
                      default: 0
                      enum:
                          - 0
                          - 1
                  description: 'When enabled, the teams will not include IDs of member users'
Generation Details

mvn generate-sources

Steps to reproduce

Generate Kotlin sources based on the OpenAPI specification shown above.

Related issues/PRs

I couldn't find any.

Suggest a fix

The type constructor shouldn't be used for enums.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the supplied OpenAPI schema through the openapi-generator-maven-plugin by running mvn generate-sources, then inspect the generated Kotlin enum and its default-value initialization. Done means number-based enums and non-null defaults produce valid Kotlin without using the enum type constructor.

Written by the indexing model from the issue text.

Assessment

Tech stack
kotlin
Domain
api, tooling
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
55/100

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