dev.langchain4j.data.message.GsonChatMessageAdapter Maven / Gradle / Ivy

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package dev.langchain4j.data.message;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonSerializationContext;
import com.google.gson.JsonSerializer;

import java.lang.reflect.Type;

class GsonChatMessageAdapter implements JsonDeserializer, JsonSerializer {

    private static final Gson GSON = new GsonBuilder()
        .registerTypeAdapter(Content.class, new GsonContentAdapter())
        .registerTypeAdapter(TextContent.class, new GsonContentAdapter())
        .registerTypeAdapter(ImageContent.class, new GsonContentAdapter())
        .registerTypeAdapter(AudioContent.class, new GsonContentAdapter())
        .registerTypeAdapter(VideoContent.class, new GsonContentAdapter())
        .registerTypeAdapter(PdfFileContent.class, new GsonContentAdapter())
        .create();

    private static final String CHAT_MESSAGE_TYPE = "type"; // do not change, will break backward compatibility!

    @Override
    public JsonElement serialize(ChatMessage chatMessage, Type ignored, JsonSerializationContext context) {
        JsonObject messageJsonObject = GSON.toJsonTree(chatMessage).getAsJsonObject();
        messageJsonObject.addProperty(CHAT_MESSAGE_TYPE, chatMessage.type().toString());
        return messageJsonObject;
    }

    @Override
    public ChatMessage deserialize(JsonElement messageJsonElement, Type ignored, JsonDeserializationContext context) {
        String chatMessageTypeString = messageJsonElement.getAsJsonObject().get(CHAT_MESSAGE_TYPE).getAsString();
        ChatMessageType chatMessageType = ChatMessageType.valueOf(chatMessageTypeString);
        ChatMessage chatMessage = GSON.fromJson(messageJsonElement, chatMessageType.messageClass());
        if (chatMessage instanceof UserMessage message && message.contents() == null) {
            // keeping backward compatibility with old schema TODO remove after a few releases
            chatMessage = UserMessage.from(messageJsonElement.getAsJsonObject().get("text").getAsString());
        }
        return chatMessage;
    }
}