[Kotlin][client] Support gson and moshi as serialization libraries

bin/openapi3/kotlin-client-petstore.sh

@@ -26,7 +26,7 @@ then
 fi
 
 export JAVA_OPTS="${JAVA_OPTS} -Xmx1024M -DloggerPath=conf/log4j.properties"
-ags="$@ generate -i modules/openapi-generator/src/test/resources/3_0/petstore-with-fake-endpoints-models-for-testing.yaml -t modules/openapi-generator/src/main/resources/kotlin-client -g kotlin --artifact-id kotlin-petstore-client --additional-properties dateLibrary=java8 -o samples/openapi3/client/petstore/kotlin $@"
+ags="generate -i modules/openapi-generator/src/test/resources/3_0/petstore-with-fake-endpoints-models-for-testing.yaml -t modules/openapi-generator/src/main/resources/kotlin-client -g kotlin --artifact-id kotlin-petstore-client --additional-properties dateLibrary=java8 -o samples/openapi3/client/petstore/kotlin $@"
 
 echo "Cleaning previously generated files if any from samples/openapi3/client/petstore/kotlin"
 rm -rf samples/openapi3/client/petstore/kotlin

docs/generators/kotlin-server.md

@@ -14,6 +14,7 @@ sidebar_label: kotlin-server
 |artifactId|Generated artifact id (name of jar).| |kotlin-server|
 |artifactVersion|Generated artifact's package version.| |1.0.0|
 |enumPropertyNaming|Naming convention for enum properties: 'camelCase', 'PascalCase', 'snake_case', 'UPPERCASE', and 'original'| |camelCase|
+|serializationLibrary|What serialization library to use: 'moshi' (default), or 'gson'| |moshi|
 |parcelizeModels|toggle "@Parcelize" for generated models| |null|
 |library|library template (sub-template)|<dl><dt>**ktor**</dt><dd>ktor framework</dd><dl>|ktor|
 |featureAutoHead|Automatically provide responses to HEAD requests for existing routes that have the GET verb defined.| |true|

docs/generators/kotlin-spring.md

@@ -14,6 +14,7 @@ sidebar_label: kotlin-spring
 |artifactId|Generated artifact id (name of jar).| |openapi-spring|
 |artifactVersion|Generated artifact's package version.| |1.0.0|
 |enumPropertyNaming|Naming convention for enum properties: 'camelCase', 'PascalCase', 'snake_case', 'UPPERCASE', and 'original'| |camelCase|
+|serializationLibrary|What serialization library to use: 'moshi' (default), or 'gson'| |moshi|
 |parcelizeModels|toggle "@Parcelize" for generated models| |null|
 |title|server title name or client service name| |OpenAPI Kotlin Spring|
 |basePackage|base package (invokerPackage) for generated code| |org.openapitools|

docs/generators/kotlin.md

@@ -14,6 +14,7 @@ sidebar_label: kotlin
 |artifactId|Generated artifact id (name of jar).| |kotlin-client|
 |artifactVersion|Generated artifact's package version.| |1.0.0|
 |enumPropertyNaming|Naming convention for enum properties: 'camelCase', 'PascalCase', 'snake_case', 'UPPERCASE', and 'original'| |camelCase|
+|serializationLibrary|What serialization library to use: 'moshi' (default), or 'gson'| |moshi|
 |parcelizeModels|toggle "@Parcelize" for generated models| |null|
 |dateLibrary|Option. Date library to use|<dl><dt>**string**</dt><dd>String</dd><dt>**java8**</dt><dd>Java 8 native JSR310</dd><dt>**threetenbp**</dt><dd>Threetenbp</dd><dl>|java8|
 |collectionType|Option. Collection type to use|<dl><dt>**array**</dt><dd>kotlin.Array</dd><dt>**list**</dt><dd>kotlin.collections.List</dd><dl>|array|

modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenConstants.java

@@ -202,6 +202,10 @@ public static enum ENUM_PROPERTY_NAMING_TYPE {camelCase, PascalCase, snake_case,
     public static final String ENUM_PROPERTY_NAMING = "enumPropertyNaming";
     public static final String ENUM_PROPERTY_NAMING_DESC = "Naming convention for enum properties: 'camelCase', 'PascalCase', 'snake_case', 'UPPERCASE', and 'original'";
 
+    // Allow different language generators to offer an option of serialization library. Each language specific
+    // Codegen constants should define a description and provide proper input validation for the value of serializationLibrary
+    public static final String SERIALIZATION_LIBRARY = "serializationLibrary";
+
     public static final String MODEL_NAME_PREFIX = "modelNamePrefix";
     public static final String MODEL_NAME_PREFIX_DESC = "Prefix that will be prepended to all model names.";
 

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractKotlinCodegen.java

@@ -35,6 +35,10 @@
 import static org.openapitools.codegen.utils.StringUtils.*;
 
 public abstract class AbstractKotlinCodegen extends DefaultCodegen implements CodegenConfig {
+
+    public static final String SERIALIZATION_LIBRARY_DESC = "What serialization library to use: 'moshi' (default), or 'gson'";
+    public enum SERIALIZATION_LIBRARY_TYPE {moshi, gson}
+
     private static final Logger LOGGER = LoggerFactory.getLogger(AbstractKotlinCodegen.class);
 
     protected String artifactId;
@@ -51,6 +55,7 @@ public abstract class AbstractKotlinCodegen extends DefaultCodegen implements Co
     protected boolean parcelizeModels = false;
 
     protected CodegenConstants.ENUM_PROPERTY_NAMING_TYPE enumPropertyNaming = CodegenConstants.ENUM_PROPERTY_NAMING_TYPE.camelCase;
+    protected SERIALIZATION_LIBRARY_TYPE serializationLibrary = SERIALIZATION_LIBRARY_TYPE.moshi;
 
     public AbstractKotlinCodegen() {
         super();
@@ -205,6 +210,10 @@ public AbstractKotlinCodegen() {
 
         CliOption enumPropertyNamingOpt = new CliOption(CodegenConstants.ENUM_PROPERTY_NAMING, CodegenConstants.ENUM_PROPERTY_NAMING_DESC);
         cliOptions.add(enumPropertyNamingOpt.defaultValue(enumPropertyNaming.name()));
+
+        CliOption serializationLibraryOpt = new CliOption(CodegenConstants.SERIALIZATION_LIBRARY, SERIALIZATION_LIBRARY_DESC);
+        cliOptions.add(serializationLibraryOpt.defaultValue(serializationLibrary.name()));
+
         cliOptions.add(new CliOption(CodegenConstants.PARCELIZE_MODELS, CodegenConstants.PARCELIZE_MODELS_DESC));
     }
 
@@ -244,6 +253,10 @@ public CodegenConstants.ENUM_PROPERTY_NAMING_TYPE getEnumPropertyNaming() {
         return this.enumPropertyNaming;
     }
 
+    public SERIALIZATION_LIBRARY_TYPE getSerializationLibrary() {
+        return this.serializationLibrary;
+    }
+
     /**
      * Sets the naming convention for Kotlin enum properties
      *
@@ -261,6 +274,24 @@ public void setEnumPropertyNaming(final String enumPropertyNamingType) {
         }
     }
 
+    /**
+     * Sets the serialization engine for Kotlin
+     *
+     * @param enumSerializationLibrary The string representation of the serialization library as defined by
+     * {@link org.openapitools.codegen.languages.AbstractKotlinCodegen.SERIALIZATION_LIBRARY_TYPE}
+     */
+    public void setSerializationLibrary(final String enumSerializationLibrary) {
+        try {
+            this.serializationLibrary = SERIALIZATION_LIBRARY_TYPE.valueOf(enumSerializationLibrary);
+        } catch (IllegalArgumentException ex) {
+            StringBuilder sb = new StringBuilder(enumSerializationLibrary + " is an invalid enum property naming option. Please choose from:");
+            for (SERIALIZATION_LIBRARY_TYPE t : SERIALIZATION_LIBRARY_TYPE.values()) {
+                sb.append("\n  ").append(t.name());
+            }
+            throw new RuntimeException(sb.toString());
+        }
+    }
+
     /**
      * returns the swagger type for the property
      *
@@ -330,6 +361,14 @@ public void processOpts() {
             setEnumPropertyNaming((String) additionalProperties.get(CodegenConstants.ENUM_PROPERTY_NAMING));
         }
 
+        if (additionalProperties.containsKey(CodegenConstants.SERIALIZATION_LIBRARY)) {
+            setSerializationLibrary((String) additionalProperties.get(CodegenConstants.SERIALIZATION_LIBRARY));
+            additionalProperties.put(this.serializationLibrary.name(), true);
+        }
+        else {
+            additionalProperties.put(this.serializationLibrary.name(), true);
+        }
+
         if (additionalProperties.containsKey(CodegenConstants.SOURCE_FOLDER)) {
             this.setSourceFolder((String) additionalProperties.get(CodegenConstants.SOURCE_FOLDER));
         } else {

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

@@ -32,6 +32,9 @@ dependencies {
     compile "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
     compile "com.squareup.moshi:moshi-kotlin:1.8.0"
     compile "com.squareup.moshi:moshi-adapters:1.8.0"
+    {{#gson}}
+    implementation "com.google.code.gson:gson:2.8.5"
+    {{/gson}}
     compile "com.squareup.okhttp3:okhttp:4.0.1"
     {{#threetenbp}}
     compile "org.threeten:threetenbp:1.3.8"

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

@@ -1,4 +1,9 @@
+{{#gson}}
+import com.google.gson.annotations.SerializedName
+{{/gson}}
+{{#moshi}}
 import com.squareup.moshi.Json
+{{/moshi}}
 {{#parcelizeModels}}
 import android.os.Parcelable
 import kotlinx.android.parcel.Parcelize
@@ -19,17 +24,22 @@ data class {{classname}} (
 {{/-last}}{{/requiredVars}}{{#hasRequired}}{{#hasOptional}},
 {{/hasOptional}}{{/hasRequired}}{{#optionalVars}}{{>data_class_opt_var}}{{^-last}},
 {{/-last}}{{/optionalVars}}
-){{#parcelizeModels}} : Parcelable{{/parcelizeModels}} {
+){{#parcelizeModels}} : Parcelable{{/parcelizeModels}}
 {{#hasEnums}}{{#vars}}{{#isEnum}}
+{
     /**
     * {{{description}}}
     * Values: {{#allowableValues}}{{#enumVars}}{{&name}}{{^-last}},{{/-last}}{{/enumVars}}{{/allowableValues}}
     */
     enum class {{{nameInCamelCase}}}(val value: {{#isListContainer}}{{{ nestedType }}}{{/isListContainer}}{{^isListContainer}}{{{dataType}}}{{/isListContainer}}){
     {{#allowableValues}}{{#enumVars}}
-        @Json(name = {{{value}}})
-        {{&name}}({{{value}}}){{^-last}},{{/-last}}{{#-last}};{{/-last}}
+        {{#moshi}}
+        @Json(name = {{{value}}}) {{&name}}({{{value}}}){{^-last}},{{/-last}}{{#-last}};{{/-last}}
+        {{/moshi}}
+        {{#gson}}
+        @SerializedName(value={{{value}}})  {{&name}}({{{value}}}){{^-last}},{{/-last}}{{#-last}};{{/-last}}
+        {{/gson}}
     {{/enumVars}}{{/allowableValues}}
     }
-{{/isEnum}}{{/vars}}{{/hasEnums}}
 }
+{{/isEnum}}{{/vars}}{{/hasEnums}}

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

@@ -1,5 +1,10 @@
 {{#description}}
     /* {{{description}}} */
 {{/description}}
+    {{#moshi}}
     @Json(name = "{{{baseName}}}")
+    {{/moshi}}
+    {{#gson}}
+    @SerializedName("{{name}}")
+    {{/gson}}
     val {{{name}}}: {{#isEnum}}{{#isListContainer}}{{#isList}}kotlin.collections.List{{/isList}}{{^isList}}kotlin.Array{{/isList}}<{{classname}}.{{{nameInCamelCase}}}>{{/isListContainer}}{{^isListContainer}}{{classname}}.{{{nameInCamelCase}}}{{/isListContainer}}{{/isEnum}}{{^isEnum}}{{{dataType}}}{{/isEnum}}? = {{#defaultvalue}}{{defaultvalue}}{{/defaultvalue}}{{^defaultvalue}}null{{/defaultvalue}}

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

@@ -1,5 +1,10 @@
 {{#description}}
     /* {{{description}}} */
 {{/description}}
+    {{#moshi}}
     @Json(name = "{{{baseName}}}")
+    {{/moshi}}
+    {{#gson}}
+    @SerializedName("{{name}}")
+    {{/gson}}
     val {{{name}}}: {{#isEnum}}{{#isListContainer}}{{#isList}}kotlin.collections.List{{/isList}}{{^isList}}kotlin.Array{{/isList}}<{{classname}}.{{{nameInCamelCase}}}>{{/isListContainer}}{{^isListContainer}}{{classname}}.{{{nameInCamelCase}}}{{/isListContainer}}{{/isEnum}}{{^isEnum}}{{{dataType}}}{{/isEnum}}

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

@@ -1,4 +1,9 @@
+{{#gson}}
+import com.google.gson.annotations.SerializedName
+{{/gson}}
+{{#moshi}}
 import com.squareup.moshi.Json
+{{/moshi}}
 
 /**
 * {{{description}}}
@@ -7,7 +12,12 @@ import com.squareup.moshi.Json
 enum class {{classname}}(val value: {{{dataType}}}){
 
 {{#allowableValues}}{{#enumVars}}
+    {{#moshi}}
     @Json(name = {{^isString}}"{{/isString}}{{{value}}}{{^isString}}"{{/isString}})
+    {{/moshi}}
+    {{#gson}}
+    @SerializedName(value = {{^isString}}"{{/isString}}{{{value}}}{{^isString}}"{{/isString}})
+    {{/gson}}
     {{#isListContainer}}
     {{#isList}}
     {{&name}}(listOf({{{value}}})){{^-last}},{{/-last}}{{#-last}};{{/-last}}

samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/models/ApiResponse.kt

@@ -26,7 +26,6 @@ data class ApiResponse (
     val type: kotlin.String? = null,
     @Json(name = "message")
     val message: kotlin.String? = null
-) {
+)
 
-}
 

samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/models/Category.kt

@@ -23,7 +23,6 @@ data class Category (
     val id: kotlin.Long? = null,
     @Json(name = "name")
     val name: kotlin.String? = null
-) {
+)
 
-}
 

samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/models/Order.kt

@@ -36,24 +36,22 @@ data class Order (
     val status: Order.Status? = null,
     @Json(name = "complete")
     val complete: kotlin.Boolean? = null
-) {
+)
 
+{
     /**
     * Order Status
     * Values: placed,approved,delivered
     */
     enum class Status(val value: kotlin.String){
 
-        @Json(name = "placed")
-        placed("placed"),
+        @Json(name = "placed") placed("placed"),
 
-        @Json(name = "approved")
-        approved("approved"),
+        @Json(name = "approved") approved("approved"),
 
-        @Json(name = "delivered")
-        delivered("delivered");
+        @Json(name = "delivered") delivered("delivered");
 
     }
-
 }
 
+

samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/models/Pet.kt

@@ -38,24 +38,22 @@ data class Pet (
     /* pet status in the store */
     @Json(name = "status")
     val status: Pet.Status? = null
-) {
+)
 
+{
     /**
     * pet status in the store
     * Values: available,pending,sold
     */
     enum class Status(val value: kotlin.String){
 
-        @Json(name = "available")
-        available("available"),
+        @Json(name = "available") available("available"),
 
-        @Json(name = "pending")
-        pending("pending"),
+        @Json(name = "pending") pending("pending"),
 
-        @Json(name = "sold")
-        sold("sold");
+        @Json(name = "sold") sold("sold");
 
     }
-
 }
 
+

samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/models/Tag.kt

@@ -23,7 +23,6 @@ data class Tag (
     val id: kotlin.Long? = null,
     @Json(name = "name")
     val name: kotlin.String? = null
-) {
+)
 
-}
 

samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/models/User.kt

@@ -42,7 +42,6 @@ data class User (
     /* User Status */
     @Json(name = "userStatus")
     val userStatus: kotlin.Int? = null
-) {
+)
 
-}
 

samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/models/ApiResponse.kt

@@ -26,7 +26,6 @@ data class ApiResponse (
     val type: kotlin.String? = null,
     @Json(name = "message")
     val message: kotlin.String? = null
-) {
+)
 
-}
 

samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/models/Category.kt

@@ -23,7 +23,6 @@ data class Category (
     val id: kotlin.Long? = null,
     @Json(name = "name")
     val name: kotlin.String? = null
-) {
+)
 
-}
 

samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/models/Order.kt

@@ -36,24 +36,22 @@ data class Order (
     val status: Order.Status? = null,
     @Json(name = "complete")
     val complete: kotlin.Boolean? = null
-) {
+)
 
+{
     /**
     * Order Status
     * Values: placed,approved,delivered
     */
     enum class Status(val value: kotlin.String){
 
-        @Json(name = "placed")
-        placed("placed"),
+        @Json(name = "placed") placed("placed"),
 
-        @Json(name = "approved")
-        approved("approved"),
+        @Json(name = "approved") approved("approved"),
 
-        @Json(name = "delivered")
-        delivered("delivered");
+        @Json(name = "delivered") delivered("delivered");
 
     }
-
 }
 
+

samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/models/Pet.kt

@@ -38,24 +38,22 @@ data class Pet (
     /* pet status in the store */
     @Json(name = "status")
     val status: Pet.Status? = null
-) {
+)
 
+{
     /**
     * pet status in the store
     * Values: available,pending,sold
     */
     enum class Status(val value: kotlin.String){
 
-        @Json(name = "available")
-        available("available"),
+        @Json(name = "available") available("available"),
 
-        @Json(name = "pending")
-        pending("pending"),
+        @Json(name = "pending") pending("pending"),
 
-        @Json(name = "sold")
-        sold("sold");
+        @Json(name = "sold") sold("sold");
 
     }
-
 }
 
+