[Backend] Fix message save

src/main/kotlin/io/openfuture/openmessanger/repository/MessageRepository.kt

@@ -6,6 +6,8 @@ import lombok.RequiredArgsConstructor
 import org.springframework.jdbc.core.RowMapper
 import org.springframework.jdbc.core.namedparam.MapSqlParameterSource
 import org.springframework.jdbc.core.namedparam.NamedParameterJdbcOperations
+import org.springframework.jdbc.support.GeneratedKeyHolder
+import org.springframework.jdbc.support.KeyHolder
 import org.springframework.stereotype.Repository
 import java.sql.ResultSet
 
@@ -159,7 +161,7 @@ class MessageRepository(
         )
     }
 
-    fun save(message: MessageEntity) {
+    fun save(message: MessageEntity): Int {
         val sql = """
                 INSERT INTO message(private_chat_id, group_chat_id, body, content_type, sender, recipient, received_at, sent_at)
                 VALUES (:privateChatId, :groupChatId, :body, :content_type, :sender, :recipient, :receivedAt, :sentAt)
@@ -174,7 +176,11 @@ class MessageRepository(
             .addValue("content_type", message.contentType.name)
             .addValue("receivedAt", message.receivedAt)
             .addValue("sentAt", message.sentAt)
-        jdbcOperations!!.update(sql, parameterSource)
+
+        val keyHolder = GeneratedKeyHolder()
+        jdbcOperations.update(sql, parameterSource, keyHolder)
+
+        return keyHolder.keys?.get("id") as Int
     }
 
     fun findGroupMessages(username: String?): List<MessageEntity> {
@@ -200,7 +206,7 @@ class MessageRepository(
                 """.trimIndent()
         val parameterSource = MapSqlParameterSource()
             .addValue("user", username)
-        return jdbcOperations!!.query(
+        return jdbcOperations.query(
             sql,
             parameterSource,
             groupMessageSelectMapper()

src/main/kotlin/io/openfuture/openmessanger/repository/entity/MessageEntity.kt

@@ -3,7 +3,7 @@ package io.openfuture.openmessanger.repository.entity
 import java.time.LocalDateTime
 
 class MessageEntity {
-    var id = 0
+    var id: Int = 0
     var body: String?
     var sender: String
     var recipient: String? = null

src/main/kotlin/io/openfuture/openmessanger/service/impl/MessageServiceImpl.kt

@@ -134,16 +134,16 @@ class MessageServiceImpl(
             LocalDateTime.now(),
             privateChat.id
         )
-        messageRepository.save(responseMessage)
+        val id = messageRepository.save(responseMessage)
         return MessageResponse(
-            message.id,
-            message.sender,
-            message.recipient!!,
+            id,
+            responseMessage.sender,
+            responseMessage.recipient!!,
             response!!,
-            message.contentType,
-            message.receivedAt!!,
-            message.sentAt,
-            message.privateChatId!!,
+            responseMessage.contentType,
+            responseMessage.receivedAt!!,
+            responseMessage.sentAt,
+            responseMessage.privateChatId!!,
             null
         )
     }