[kotlin-client] Support for integer enums for multiplatform with custom serializer (#23211)

* use custom serializer for non string enums for multiplatform library

* add missing imports

* add tests for enum integers

---------

Co-authored-by: rlnt <relentless@rlnt.dev>

Author: wing328

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

@@ -48,6 +48,7 @@ jobs:
           - samples/client/petstore/kotlin-default-values-jvm-okhttp4
           - samples/client/petstore/kotlin-default-values-jvm-retrofit2
           - samples/client/petstore/kotlin-default-values-multiplatform
+          - samples/client/petstore/kotlin-enum-integers-multiplatform
           - samples/client/petstore/kotlin-array-simple-string-jvm-okhttp4
           - samples/client/petstore/kotlin-array-simple-string-multiplatform
           - samples/client/petstore/kotlin-bigdecimal-default-multiplatform

bin/configs/kotlin-enum-integers-multiplatform.yaml

@@ -0,0 +1,9 @@
+generatorName: kotlin
+outputDir: samples/client/petstore/kotlin-enum-integers-multiplatform
+inputSpec: modules/openapi-generator/src/test/resources/3_0/issue_21204_enum_integers.yaml
+templateDir: modules/openapi-generator/src/main/resources/kotlin-client
+additionalProperties:
+  artifactId: kotlin-enum-integers-multiplatform
+  library: multiplatform
+  dateLibrary: kotlinx-datetime
+  sortParamsByRequiredFlag: false

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

@@ -42,14 +42,17 @@ import kotlinx.serialization.encoding.Encoder
 {{/multiplatform}}
 {{#multiplatform}}
 import kotlinx.serialization.*
+import kotlinx.serialization.builtins.serializer
+import kotlinx.serialization.encoding.Decoder
+import kotlinx.serialization.encoding.Encoder
 {{/multiplatform}}
 
 /**
  * {{{description}}}
  *
  * Values: {{#allowableValues}}{{#enumVars}}{{&name}}{{^-last}},{{/-last}}{{/enumVars}}{{/allowableValues}}
  */
-{{#multiplatform}}@Serializable{{/multiplatform}}{{#kotlinx_serialization}}@Serializable{{#enumUnknownDefaultCase}}(with = {{classname}}Serializer::class){{/enumUnknownDefaultCase}}{{^enumUnknownDefaultCase}}{{^isString}}(with = {{classname}}Serializer::class){{/isString}}{{/enumUnknownDefaultCase}}{{/kotlinx_serialization}}
+{{#multiplatform}}@Serializable{{^isString}}(with = {{classname}}Serializer::class){{/isString}}{{/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)
@@ -74,7 +77,9 @@ import kotlinx.serialization.*
     {{/kotlinx_serialization}}
     {{/multiplatform}}
     {{#multiplatform}}
+    {{#isString}}
     @SerialName(value = {{#lambda.doublequote}}{{{value}}}{{/lambda.doublequote}})
+    {{/isString}}
     {{/multiplatform}}
     {{#isArray}}
     {{#isList}}
@@ -172,3 +177,20 @@ internal object {{classname}}Serializer : KSerializer<{{classname}}> {
 }
 {{/isString}}{{/enumUnknownDefaultCase}}
 {{/kotlinx_serialization}}
+{{#multiplatform}}
+{{^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)
+    }
+}
+{{/isString}}
+{{/multiplatform}}

modules/openapi-generator/src/test/resources/3_0/issue_21204_enum_integers.yaml

@@ -0,0 +1,30 @@
+openapi: 3.0.3
+info:
+  title: Demo
+  version: v1
+
+components:
+  schemas:
+    Code:
+      type: integer
+      enum:
+        - 0
+        - 1
+        - 2
+
+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/petstore/kotlin-enum-integers-multiplatform/.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/petstore/kotlin-enum-integers-multiplatform/.openapi-generator/FILES

@@ -0,0 +1,26 @@
+README.md
+build.gradle.kts
+docs/Code.md
+docs/DefaultApi.md
+docs/DoGet200Response.md
+gradle/wrapper/gradle-wrapper.jar
+gradle/wrapper/gradle-wrapper.properties
+gradlew
+gradlew.bat
+settings.gradle.kts
+src/commonMain/kotlin/org/openapitools/client/apis/DefaultApi.kt
+src/commonMain/kotlin/org/openapitools/client/auth/ApiKeyAuth.kt
+src/commonMain/kotlin/org/openapitools/client/auth/Authentication.kt
+src/commonMain/kotlin/org/openapitools/client/auth/HttpBasicAuth.kt
+src/commonMain/kotlin/org/openapitools/client/auth/HttpBearerAuth.kt
+src/commonMain/kotlin/org/openapitools/client/auth/OAuth.kt
+src/commonMain/kotlin/org/openapitools/client/infrastructure/ApiAbstractions.kt
+src/commonMain/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
+src/commonMain/kotlin/org/openapitools/client/infrastructure/Base64ByteArray.kt
+src/commonMain/kotlin/org/openapitools/client/infrastructure/HttpResponse.kt
+src/commonMain/kotlin/org/openapitools/client/infrastructure/OctetByteArray.kt
+src/commonMain/kotlin/org/openapitools/client/infrastructure/PartConfig.kt
+src/commonMain/kotlin/org/openapitools/client/infrastructure/RequestConfig.kt
+src/commonMain/kotlin/org/openapitools/client/infrastructure/RequestMethod.kt
+src/commonMain/kotlin/org/openapitools/client/models/Code.kt
+src/commonMain/kotlin/org/openapitools/client/models/DoGet200Response.kt

samples/client/petstore/kotlin-enum-integers-multiplatform/.openapi-generator/VERSION

@@ -0,0 +1 @@
+7.21.0-SNAPSHOT

samples/client/petstore/kotlin-enum-integers-multiplatform/README.md

@@ -0,0 +1,53 @@
+# 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: 7.21.0-SNAPSHOT
+- Build package: org.openapitools.codegen.languages.KotlinClientCodegen
+
+## Requires
+
+* Kotlin 2.2.20
+
+## Build
+
+```
+./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.
+
+
+<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)
+
+
+<a id="documentation-for-authorization"></a>
+## Documentation for Authorization
+
+Endpoints do not require authorization.
+

samples/client/petstore/kotlin-enum-integers-multiplatform/build.gradle.kts

@@ -0,0 +1,97 @@
+import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinNativeTarget
+
+plugins {
+    kotlin("multiplatform") version "2.2.20" // kotlin_version
+    kotlin("plugin.serialization") version "2.2.20" // kotlin_version
+}
+
+group = "org.openapitools"
+version = "1.0.0"
+
+val kotlin_version = "2.2.20"
+val coroutines_version = "1.10.2"
+val serialization_version = "1.9.0"
+val ktor_version = "3.2.3"
+
+repositories {
+    mavenCentral()
+}
+
+kotlin {
+    jvm()
+    iosX64()
+    iosArm64()
+    iosSimulatorArm64()
+    js {
+        browser()
+        nodejs()
+    }
+
+    sourceSets {
+        commonMain {
+            dependencies {
+                implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutines_version")
+                implementation("org.jetbrains.kotlinx:kotlinx-serialization-core:$serialization_version")
+
+                api("io.ktor:ktor-client-core:$ktor_version")
+                api("io.ktor:ktor-client-serialization:$ktor_version")
+                api("io.ktor:ktor-client-content-negotiation:$ktor_version")
+                api("io.ktor:ktor-serialization-kotlinx-json:$ktor_version")
+
+                api("org.jetbrains.kotlinx:kotlinx-datetime:0.7.1")
+            }
+        }
+
+        commonTest {
+            dependencies {
+                implementation(kotlin("test"))
+                implementation("io.ktor:ktor-client-mock:$ktor_version")
+            }
+        }
+
+        jvmMain {
+            dependencies {
+                implementation(kotlin("stdlib-jdk7"))
+                implementation("io.ktor:ktor-client-cio-jvm:$ktor_version")
+            }
+        }
+
+        jvmTest {
+            dependencies {
+                implementation(kotlin("test-junit"))
+            }
+        }
+
+        iosMain {
+            dependencies {
+                api("io.ktor:ktor-client-ios:$ktor_version")
+            }
+        }
+
+        jsMain {
+            dependencies {
+                api("io.ktor:ktor-client-js:$ktor_version")
+            }
+        }
+
+        all {
+            languageSettings {
+                optIn("kotlin.time.ExperimentalTime")
+            }
+        }
+    }
+}
+
+tasks {
+    register<Exec>("iosTest") {
+        val device = project.findProperty("device")?.toString() ?: "iPhone 8"
+        dependsOn("linkDebugTestIosX64")
+        group = JavaBasePlugin.VERIFICATION_GROUP
+        description = "Execute unit tests on ${device} simulator"
+        val binary = kotlin.targets.getByName<KotlinNativeTarget>("iosX64").binaries.getTest("DEBUG")
+        commandLine("xcrun", "simctl", "spawn", device, binary.outputFile)
+    }
+    register("test") {
+        dependsOn("allTests")
+    }
+}

samples/client/petstore/kotlin-enum-integers-multiplatform/docs/Code.md

@@ -0,0 +1,14 @@
+
+# Code
+
+## Enum
+
+
+    * `_0` (value: `0`)
+
+    * `_1` (value: `1`)
+
+    * `_2` (value: `2`)
+
+
+