Use Kotlinx Serialization in Spring Boot instead of Jackson

4 files changed, 16 insertions, 6 deletions

diff --git a/sw-server/build.gradle.kts b/sw-server/build.gradle.kts
index 2e281a12..96990dc7 100644
--- a/sw-server/build.gradle.kts
+++ b/sw-server/build.gradle.kts
@@ -1,6 +1,7 @@
 plugins {
     kotlin("jvm")
     kotlin("plugin.spring")
+    kotlin("plugin.serialization")
     id("org.springframework.boot") version "2.4.0"
 }
 
@@ -12,21 +13,19 @@ dependencies {
     implementation(project(":sw-bot"))
     implementation(kotlin("reflect")) // required by Spring 5
     implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.4.1")
+    implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.0.1")
 
     implementation("org.springframework.boot:spring-boot-starter-websocket")
     implementation("org.springframework.boot:spring-boot-starter-security")
     // required by spring security when using websockets
     implementation("org.springframework.security:spring-security-messaging")
 
-    implementation("com.fasterxml.jackson.module:jackson-module-kotlin")
-
     implementation("ch.qos.logback:logback-classic:1.1.8")
 
     testImplementation(kotlin("test"))
     testImplementation(kotlin("test-junit"))
     testImplementation(project(":sw-client"))
     testImplementation("org.springframework.boot:spring-boot-starter-test")
-    testImplementation("com.fasterxml.jackson.module:jackson-module-kotlin")
 }
 
 tasks.processResources {
diff --git a/sw-server/src/main/kotlin/org/luxons/sevenwonders/server/config/WebSocketConfig.kt b/sw-server/src/main/kotlin/org/luxons/sevenwonders/server/config/WebSocketConfig.kt
index aad1c2ce..2782c670 100644
--- a/sw-server/src/main/kotlin/org/luxons/sevenwonders/server/config/WebSocketConfig.kt
+++ b/sw-server/src/main/kotlin/org/luxons/sevenwonders/server/config/WebSocketConfig.kt
@@ -3,6 +3,8 @@ package org.luxons.sevenwonders.server.config
 import org.luxons.sevenwonders.model.api.SEVEN_WONDERS_WS_ENDPOINT
 import org.springframework.context.annotation.Bean
 import org.springframework.context.annotation.Configuration
+import org.springframework.messaging.converter.KotlinSerializationJsonMessageConverter
+import org.springframework.messaging.converter.MessageConverter
 import org.springframework.messaging.simp.config.ChannelRegistration
 import org.springframework.messaging.simp.config.MessageBrokerRegistry
 import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler
@@ -48,4 +50,9 @@ class WebSocketConfig(
     override fun configureClientInboundChannel(registration: ChannelRegistration) {
         registration.interceptors(topicSubscriptionInterceptor)
     }
+
+    override fun configureMessageConverters(messageConverters: MutableList<MessageConverter>): Boolean {
+        messageConverters.add(KotlinSerializationJsonMessageConverter())
+        return true
+    }
 }
diff --git a/sw-server/src/main/kotlin/org/luxons/sevenwonders/server/controllers/GameBrowserController.kt b/sw-server/src/main/kotlin/org/luxons/sevenwonders/server/controllers/GameBrowserController.kt
index b63f6756..587afc10 100644
--- a/sw-server/src/main/kotlin/org/luxons/sevenwonders/server/controllers/GameBrowserController.kt
+++ b/sw-server/src/main/kotlin/org/luxons/sevenwonders/server/controllers/GameBrowserController.kt
@@ -36,7 +36,7 @@ class GameBrowserController(
      * @return the current list of [Lobby]s
      */
     @SubscribeMapping("/games") // prefix /topic not shown
-    fun listGames(principal: Principal): Collection<LobbyDTO> {
+    fun listGames(principal: Principal): List<LobbyDTO> {
         logger.info("Player '{}' subscribed to /topic/games", principal.name)
         return lobbyRepository.list().map { it.toDTO() }
     }
@@ -61,7 +61,9 @@ class GameBrowserController(
 
         // notify everyone that a new game exists
         val lobbyDto = lobby.toDTO()
-        template.convertAndSend("/topic/games", listOf(lobbyDto))
+        // we need to pass a non-generic type (array is fine) so that Spring doesn't break when trying to find a
+        // serializer from Kotlinx Serialization
+        template.convertAndSend("/topic/games", listOf(lobbyDto).toTypedArray())
         return lobbyDto
     }
 
diff --git a/sw-server/src/main/kotlin/org/luxons/sevenwonders/server/controllers/LobbyController.kt b/sw-server/src/main/kotlin/org/luxons/sevenwonders/server/controllers/LobbyController.kt
index fccb9b5b..7757c9d9 100644
--- a/sw-server/src/main/kotlin/org/luxons/sevenwonders/server/controllers/LobbyController.kt
+++ b/sw-server/src/main/kotlin/org/luxons/sevenwonders/server/controllers/LobbyController.kt
@@ -113,7 +113,9 @@ class LobbyController(
         lobby.getPlayers().forEach {
             template.convertAndSendToUser(it.username, "/queue/lobby/updated", lobby.toDTO())
         }
-        template.convertAndSend("/topic/games", listOf(lobby.toDTO()))
+        // we need to pass a non-generic type (array is fine) so that Spring doesn't break when trying to find a
+        // serializer from Kotlinx Serialization
+        template.convertAndSend("/topic/games", listOf(lobby.toDTO()).toTypedArray())
     }
 
     /**