Quarkus Langchain4j: Custom ChatMemoryStore does not update messages in MongoDB

[KhairAli]

Hi, Since there is an official example of ChatMemoryStore in redis, but redis i want to use mongodb to maintain chat context, below is code

import io.quarkus.mongodb.panache.PanacheMongoEntity;
import io.quarkus.mongodb.panache.common.MongoEntity;
import org.bson.codecs.pojo.annotations.BsonProperty;

import java.time.Instant;
import java.util.List;

@MongoEntity(collection = "chat_session")
public class ChatSession extends PanacheMongoEntity {


    @BsonProperty("user_session")
    public String userSession;

    @BsonProperty("org_id")
    public String orgId;

    @BsonProperty("chat_message")
    public List<Conversation> conversations;

    public static class Conversation {

        public String type;

        public String message;

        public Instant timestamp;
    }
}

import dev.langchain4j.data.message.ChatMessage;
import dev.langchain4j.data.message.ChatMessageType;
import dev.langchain4j.store.memory.chat.ChatMemoryStore;
import io.quarkus.logging.Log;
import jakarta.enterprise.context.ApplicationScoped;
import org.blackandblack.ai.entity.mongo.ChatSession;

import java.time.Instant;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;

@ApplicationScoped
public class MemoryBean implements ChatMemoryStore {

    @Override
    public void deleteMessages(Object memoryId) {
    }

    @Override
    public List<ChatMessage> getMessages(Object memoryId) {
        ChatSession session = ChatSession.find("userSession", memoryId).firstResult();
        Log.infof("%s calling getMessages )))))))))))))))))))))))))))))))))))))))))))))))))000", session);
        if (session == null || session.conversations == null) {
            Log.infof("%s Empty session", session);
            return Collections.emptyList();
        }
        return session.conversations.stream()
                .map(conv -> new ChatMessage() {
                    @Override
                    public ChatMessageType type() {
                        return ChatMessageType.valueOf(conv.type);
                    }

                    @Override
                    public String text() {
                        return conv.message;
                    }
                })
                .collect(Collectors.toList());
    }

    @Override
    public void updateMessages(Object memoryId, List<ChatMessage> messages) {
        ChatSession session = ChatSession.find("userSession", memoryId).firstResult();
        Log.infof("%s fetch result#########################################3", session);
        if (session == null) {
            session = new ChatSession();
            session.userSession = memoryId.toString();
        }

        Log.infof("%s updateMessages", session);

        List<ChatSession.Conversation> converted = messages.stream()
                .map(msg -> {
                    ChatSession.Conversation conv = new ChatSession.Conversation();
                    conv.type = msg.type().toString();
                    conv.message = msg.text();
                    conv.timestamp = Instant.now();
                    return conv;
                })
                .collect(Collectors.toList());

        session.userSession = memoryId.toString();
        session.conversations = converted;
        session.persistOrUpdate();
    }
}

import dev.langchain4j.service.MemoryId;
import dev.langchain4j.service.SystemMessage;
import dev.langchain4j.service.UserMessage;
import io.quarkiverse.langchain4j.RegisterAiService;
import org.blackandblack.dto.ChatDTO;

/**
 * This is a sample Bot, it is configured to ingest the 'easy-rag-catalog/'.
 * You can @Inject this Bot in your Rest resource
 * <p>
 * \{@code
 *
 * @Inject Bot bot;
 * @POST
 * @Produces(MediaType.TEXT_PLAIN) public String chat(String q) {
 * return bot.chat(q);
 * }
 * }
 */
@RegisterAiService()
public interface Bot {

    @SystemMessage("""
            You are an AI named Bot answering questions about E-commerce.
            Your response must be polite, use the same language as the question, use english response by default, and be relevant to the question.
            When you don't know, respond that you don't know the answer and the merchant will contact the customer directly.
            """)
    String chat(@MemoryId String session, @UserMessage String question);
}

import jakarta.inject.Inject;
import jakarta.ws.rs.POST;
import jakarta.ws.rs.Path;
import org.blackandblack.ai.serivce.Bot;
import org.blackandblack.dto.ChatDTO;


@Path("/ai/chat")
public class ChatResource {

    @Inject
    Bot bot;

    @POST
    public String triage(ChatDTO chat) {
        return bot.chat(chat.userSession,chat.message);
    }

}

and partial yml properties

    langchain4j:
      openai:
        api-key: ${OPEN_ROUTER_API_KEY}
        base-url: https://openrouter.ai/api/v1
        log-requests: true
        log-responses: true
        chat-model:
          model-name: ${OPEN_ROUTER_MODEL_NAME}
          temperature: 0
        chat-memory:
          type: MESSAGE_WINDOW|TOKEN_WINDOW
          memory-window:
            max-messages: 20

quarkusPluginId=io.quarkus
quarkusPluginVersion=3.13.2
quarkusPlatformGroupId=io.quarkus.platform
quarkusPlatformArtifactId=quarkus-bom
quarkusPlatformVersion=3.13.2

When i call API first time it save data in mongodb successfully

But when i make 2nd request, i am getting below error

{"requestId":"2bf0223f-bb01-4bc1-9e92-9131ec72f501","statusCode":400,"errorCode":"-0001","message":"Unknown message type: SYSTEM","createdAt":"2025-06-28T22:43:47.218+00:00"}

[KhairAli]

This feature released in 1.1.0 CR1

[quarkus-bot[bot]]

/cc @loicmathieu (mongodb)