[kotlin-client] Support for integer enums with kotlinx with custom serializer (#21765)

* [kotlin-client] Add support for integer enums with custom serializer for kotlinx

* [kotlin-client] Fix @SerialName annotation being used on non-string enums

* Format samples

* remove blank line

* add tests for kotlin client with integer enum

* add folders

---------

Co-authored-by: CHervaudBetclic <c.hervaud@betclicgroup.com>

Author: wing328

.github/workflows/samples-kotlin-client.yaml

@@ -5,10 +5,12 @@ on:
     branches:
       - 'samples/client/petstore/kotlin*/**'
       - 'samples/client/others/kotlin-jvm-okhttp-parameter-tests/**'
+      - samples/client/others/kotlin-integer-enum/**
   pull_request:
     paths:
       - 'samples/client/petstore/kotlin*/**'
       - 'samples/client/others/kotlin-jvm-okhttp-parameter-tests/**'
+      - samples/client/others/kotlin-integer-enum/**
 
 jobs:
   build:
@@ -66,6 +68,7 @@ jobs:
           - samples/client/petstore/kotlin-name-parameter-mappings
           - samples/client/others/kotlin-jvm-okhttp-parameter-tests
           - samples/client/others/kotlin-jvm-okhttp-path-comments
+          - samples/client/others/kotlin-integer-enum
           - samples/client/petstore/kotlin-allOff-discriminator-kotlinx-serialization
     steps:
       - uses: actions/checkout@v5

bin/configs/kotlin-integer-enum.yaml

@@ -0,0 +1,6 @@
+generatorName: kotlin
+outputDir: samples/client/others/kotlin-integer-enum
+inputSpec: modules/openapi-generator/src/test/resources/3_0/pr_21746.yaml
+templateDir: modules/openapi-generator/src/main/resources/kotlin-client
+additionalProperties:
+  artifactId: kotlin-integer-enum

modules/openapi-generator/src/main/resources/kotlin-client/enum_class.mustache

@@ -18,10 +18,23 @@ import kotlinx.serialization.Serializable
 {{#enumUnknownDefaultCase}}
 import kotlinx.serialization.KSerializer
 import kotlinx.serialization.Serializer
+{{^isString}}
+import kotlinx.serialization.descriptors.PrimitiveKind
+import kotlinx.serialization.descriptors.PrimitiveSerialDescriptor
+{{/isString}}
 import kotlinx.serialization.builtins.serializer
 import kotlinx.serialization.encoding.Decoder
 import kotlinx.serialization.encoding.Encoder
 {{/enumUnknownDefaultCase}}
+{{^enumUnknownDefaultCase}}{{^isString}}
+import kotlinx.serialization.KSerializer
+import kotlinx.serialization.Serializer
+import kotlinx.serialization.descriptors.PrimitiveKind
+import kotlinx.serialization.descriptors.PrimitiveSerialDescriptor
+import kotlinx.serialization.builtins.serializer
+import kotlinx.serialization.encoding.Decoder
+import kotlinx.serialization.encoding.Encoder
+{{/isString}}{{/enumUnknownDefaultCase}}
 {{/kotlinx_serialization}}
 {{/multiplatform}}
 {{#multiplatform}}
@@ -33,7 +46,7 @@ import kotlinx.serialization.*
  *
  * Values: {{#allowableValues}}{{#enumVars}}{{&name}}{{^-last}},{{/-last}}{{/enumVars}}{{/allowableValues}}
  */
-{{#multiplatform}}@Serializable{{/multiplatform}}{{#kotlinx_serialization}}@Serializable{{#enumUnknownDefaultCase}}(with = {{classname}}Serializer::class){{/enumUnknownDefaultCase}}{{/kotlinx_serialization}}
+{{#multiplatform}}@Serializable{{/multiplatform}}{{#kotlinx_serialization}}@Serializable{{#enumUnknownDefaultCase}}(with = {{classname}}Serializer::class){{/enumUnknownDefaultCase}}{{^enumUnknownDefaultCase}}{{^isString}}(with = {{classname}}Serializer::class){{/isString}}{{/enumUnknownDefaultCase}}{{/kotlinx_serialization}}
 {{^multiplatform}}
 {{#moshi}}
 @JsonClass(generateAdapter = false)
@@ -52,7 +65,9 @@ import kotlinx.serialization.*
     @JsonProperty(value = {{#lambda.doublequote}}{{{value}}}{{/lambda.doublequote}}){{#enumUnknownDefaultCase}}{{#-last}} @JsonEnumDefaultValue{{/-last}}{{/enumUnknownDefaultCase}}
     {{/jackson}}
     {{#kotlinx_serialization}}
+    {{#isString}}
     @SerialName(value = {{#lambda.doublequote}}{{{value}}}{{/lambda.doublequote}})
+    {{/isString}}
     {{/kotlinx_serialization}}
     {{/multiplatform}}
     {{#multiplatform}}
@@ -95,18 +110,40 @@ import kotlinx.serialization.*
           }
         }
     }
-}{{#kotlinx_serialization}}{{#enumUnknownDefaultCase}}
-
+}
+{{#kotlinx_serialization}}{{#enumUnknownDefaultCase}}
 internal object {{classname}}Serializer : KSerializer<{{classname}}> {
-    override val descriptor = {{{dataType}}}.serializer().descriptor
+    override val descriptor = {{dataType}}.serializer().descriptor
 
     override fun deserialize(decoder: Decoder): {{classname}} {
         val value = decoder.decodeSerializableValue({{{dataType}}}.serializer())
         return {{classname}}.values().firstOrNull { it.value == value }
+            {{#isString}}
             ?: {{classname}}.{{#allowableValues}}{{#enumVars}}{{#-last}}{{&name}}{{/-last}}{{/enumVars}}{{/allowableValues}}
+            {{/isString}}
+            {{^isString}}
+            ?: throw IllegalArgumentException("Unknown enum value: $value")
+            {{/isString}}
+    }
+
+    override fun serialize(encoder: Encoder, value: {{classname}}) {
+        encoder.encodeSerializableValue({{{dataType}}}.serializer(), value.value)
+    }
+}
+{{/enumUnknownDefaultCase}}
+{{^enumUnknownDefaultCase}}{{^isString}}
+internal object {{classname}}Serializer : KSerializer<{{classname}}> {
+    override val descriptor = {{dataType}}.serializer().descriptor
+
+    override fun deserialize(decoder: Decoder): {{classname}} {
+        val value = decoder.decodeSerializableValue({{{dataType}}}.serializer())
+        return {{classname}}.values().firstOrNull { it.value == value }
+            ?: throw IllegalArgumentException("Unknown enum value: $value")
     }
 
     override fun serialize(encoder: Encoder, value: {{classname}}) {
         encoder.encodeSerializableValue({{{dataType}}}.serializer(), value.value)
     }
-}{{/enumUnknownDefaultCase}}{{/kotlinx_serialization}}
+}
+{{/isString}}{{/enumUnknownDefaultCase}}
+{{/kotlinx_serialization}}

modules/openapi-generator/src/test/resources/3_0/pr_21746.yaml

@@ -0,0 +1,34 @@
+openapi: 3.0.3
+info:
+  title: Demo
+  version: v1
+
+components:
+  schemas:
+    Code:
+      type: integer
+      enum:
+        - 0
+        - 1
+    StringCode:
+      type: string
+      enum:
+        - hello
+        - world
+
+paths:
+  /do:
+    get:
+      summary: Do something
+      responses:
+        200:
+          description: Successful response
+          content:
+            application/json:
+              schema:
+                type: object
+                required:
+                  - code
+                properties:
+                  code:
+                    $ref: '#/components/schemas/Code'

samples/client/others/kotlin-integer-enum/.openapi-generator-ignore

@@ -0,0 +1,23 @@
+# OpenAPI Generator Ignore
+# Generated by openapi-generator https://github.com/openapitools/openapi-generator
+
+# Use this file to prevent files from being overwritten by the generator.
+# The patterns follow closely to .gitignore or .dockerignore.
+
+# As an example, the C# client generator defines ApiClient.cs.
+# You can make changes and tell OpenAPI Generator to ignore just this file by uncommenting the following line:
+#ApiClient.cs
+
+# You can match any string of characters against a directory, file or extension with a single asterisk (*):
+#foo/*/qux
+# The above matches foo/bar/qux and foo/baz/qux, but not foo/bar/baz/qux
+
+# You can recursively match patterns against a directory, file or extension with a double asterisk (**):
+#foo/**/qux
+# This matches foo/bar/qux, foo/baz/qux, and foo/bar/baz/qux
+
+# You can also negate patterns with an exclamation (!).
+# For example, you can ignore all files in a docs folder with the file extension .md:
+#docs/*.md
+# Then explicitly reverse the ignore rule for a single file:
+#!docs/README.md

samples/client/others/kotlin-integer-enum/.openapi-generator/FILES

@@ -0,0 +1,32 @@
+README.md
+build.gradle
+docs/Code.md
+docs/DefaultApi.md
+docs/DoGet200Response.md
+docs/StringCode.md
+gradle/wrapper/gradle-wrapper.jar
+gradle/wrapper/gradle-wrapper.properties
+gradlew
+gradlew.bat
+settings.gradle
+src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
+src/main/kotlin/org/openapitools/client/infrastructure/ApiAbstractions.kt
+src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
+src/main/kotlin/org/openapitools/client/infrastructure/ApiResponse.kt
+src/main/kotlin/org/openapitools/client/infrastructure/BigDecimalAdapter.kt
+src/main/kotlin/org/openapitools/client/infrastructure/BigIntegerAdapter.kt
+src/main/kotlin/org/openapitools/client/infrastructure/ByteArrayAdapter.kt
+src/main/kotlin/org/openapitools/client/infrastructure/Errors.kt
+src/main/kotlin/org/openapitools/client/infrastructure/LocalDateAdapter.kt
+src/main/kotlin/org/openapitools/client/infrastructure/LocalDateTimeAdapter.kt
+src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+src/main/kotlin/org/openapitools/client/infrastructure/PartConfig.kt
+src/main/kotlin/org/openapitools/client/infrastructure/RequestConfig.kt
+src/main/kotlin/org/openapitools/client/infrastructure/RequestMethod.kt
+src/main/kotlin/org/openapitools/client/infrastructure/ResponseExtensions.kt
+src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
+src/main/kotlin/org/openapitools/client/infrastructure/URIAdapter.kt
+src/main/kotlin/org/openapitools/client/infrastructure/UUIDAdapter.kt
+src/main/kotlin/org/openapitools/client/models/Code.kt
+src/main/kotlin/org/openapitools/client/models/DoGet200Response.kt
+src/main/kotlin/org/openapitools/client/models/StringCode.kt

samples/client/others/kotlin-integer-enum/.openapi-generator/VERSION

@@ -0,0 +1 @@
+7.15.0-SNAPSHOT

samples/client/others/kotlin-integer-enum/README.md

@@ -0,0 +1,63 @@
+# org.openapitools.client - Kotlin client library for Demo
+
+No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+
+## Overview
+This API client was generated by the [OpenAPI Generator](https://openapi-generator.tech) project.  By using the [openapi-spec](https://github.com/OAI/OpenAPI-Specification) from a remote server, you can easily generate an API client.
+
+- API version: v1
+- Package version: 
+- Generator version: 7.15.0-SNAPSHOT
+- Build package: org.openapitools.codegen.languages.KotlinClientCodegen
+
+## Requires
+
+* Kotlin 1.7.21
+* Gradle 7.5
+
+## Build
+
+First, create the gradle wrapper script:
+
+```
+gradle wrapper
+```
+
+Then, run:
+
+```
+./gradlew check assemble
+```
+
+This runs all tests and packages the library.
+
+## Features/Implementation Notes
+
+* Supports JSON inputs/outputs, File inputs, and Form inputs.
+* Supports collection formats for query parameters: csv, tsv, ssv, pipes.
+* Some Kotlin and Java types are fully qualified to avoid conflicts with types defined in OpenAPI definitions.
+* Implementation of ApiClient is intended to reduce method counts, specifically to benefit Android targets.
+
+<a id="documentation-for-api-endpoints"></a>
+## Documentation for API Endpoints
+
+All URIs are relative to *http://localhost*
+
+| Class | Method | HTTP request | Description |
+| ------------ | ------------- | ------------- | ------------- |
+| *DefaultApi* | [**doGet**](docs/DefaultApi.md#doget) | **GET** /do | Do something |
+
+
+<a id="documentation-for-models"></a>
+## Documentation for Models
+
+ - [org.openapitools.client.models.Code](docs/Code.md)
+ - [org.openapitools.client.models.DoGet200Response](docs/DoGet200Response.md)
+ - [org.openapitools.client.models.StringCode](docs/StringCode.md)
+
+
+<a id="documentation-for-authorization"></a>
+## Documentation for Authorization
+
+Endpoints do not require authorization.
+

samples/client/others/kotlin-integer-enum/build.gradle

@@ -0,0 +1,62 @@
+group 'org.openapitools'
+version '1.0.0'
+
+wrapper {
+    gradleVersion = '8.7'
+    distributionUrl = "https://services.gradle.org/distributions/gradle-$gradleVersion-all.zip"
+}
+
+buildscript {
+    ext.kotlin_version = '1.9.23'
+    ext.spotless_version = "6.25.0"
+
+    repositories {
+        maven { url "https://repo1.maven.org/maven2" }
+    }
+    dependencies {
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+        classpath "com.diffplug.spotless:spotless-plugin-gradle:$spotless_version"
+    }
+}
+
+apply plugin: 'kotlin'
+apply plugin: 'maven-publish'
+apply plugin: 'com.diffplug.spotless'
+
+repositories {
+    maven { url "https://repo1.maven.org/maven2" }
+}
+
+// Use spotless plugin to automatically format code, remove unused import, etc
+// To apply changes directly to the file, run `gradlew spotlessApply`
+// Ref: https://github.com/diffplug/spotless/tree/main/plugin-gradle
+spotless {
+    // comment out below to run spotless as part of the `check` task
+    enforceCheck false
+
+    format 'misc', {
+        // define the files (e.g. '*.gradle', '*.md') to apply `misc` to
+        target '.gitignore'
+
+        // define the steps to apply to those files
+        trimTrailingWhitespace()
+        indentWithSpaces() // Takes an integer argument if you don't like 4
+        endWithNewline()
+    }
+    kotlin {
+        ktfmt()
+    }
+}
+
+test {
+    useJUnitPlatform()
+}
+
+dependencies {
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
+    implementation "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
+    implementation "com.squareup.moshi:moshi-kotlin:1.15.1"
+    implementation "com.squareup.moshi:moshi-adapters:1.15.1"
+    implementation "com.squareup.okhttp3:okhttp:4.12.0"
+    testImplementation "io.kotlintest:kotlintest-runner-junit5:3.4.2"
+}

samples/client/others/kotlin-integer-enum/docs/Code.md

@@ -0,0 +1,12 @@
+
+# Code
+
+## Enum
+
+
+    * `_0` (value: `0`)
+
+    * `_1` (value: `1`)
+
+
+