Persisting bi-directional entities with Green-DAO

Question

as you can probably remember from my previous question about bidirectional relations in Green DAO, I have a chat that consists of conversations and messages.
every message has a parent conversation, and the conversation has a list of messages.

when I try and add a new message, it works perfectly as long as I don't close the application.
This is the code I use for adding a message to an existing conversation:

I now have my code that does this:

Conversation conv = getConversation();
List<Message> list = conv.getMessageList();

Message msg = new Message();
msg.setConversationId(conv,getId());
MessageDao.insert(msg);


list.add(msg);

conv.update();
// ConversationDao.update(conv);

when I open the application the next time and call conv.getMessageList(), the result is an empty ArrayList.

what am I doing wrong?

EDIT:

I changed my code and now it looks like this:

Conversation conv= getCOnversation();

Message msg = new Message();
msg.setConversation(conv);
MessageDao.insert(msg);

conv.resetMessageList();

unfortunately, now more than ever (even on same run), still calling conv.getMessageList() returns an empty java.list.

EDIT 2:

here is code for the generator (this is not the real code, but only what is important to the question.

Entity message = schema.addEntity("Message");
message.addIdProperty().autoincrement();

Entity conversation =schema.addEntity("Conversation");
conversation.addIdProperty().autoincrement();

Property parentConversation = message.addLongProperty("parentConversation")
        .getProperty();
Property messages = conversation.addLongProperty("messages").getProperty();
message.addToOne(conversation, parentConversation);
conversation.addToMany(message, messages);

EDIT 3

for now, instead of calling conv.getMessageList(); I running this line and it work fine.

List<Message> messageList = MessageDao.queryBuilder()
    .where(Properties.parentConversation.eq(conv.getId())
    .list()

I suspect a major issue for me or greenrobot in the implementation of all this.

is this an issue of running the above code while Session.runInTx?

Answer 1

This is the problematic section:

Property parentConversation = message.addLongProperty("parent")
    .getProperty();
Property messages = conversation.addLongProperty("messages")
    .getProperty();

message.addToOne(conversation, parentConversation);
conversation.addToMany(message, messages);

For 1:N relations, you must use the same property for both your ToOne and ToMany relation. Try this and regenerate your code:

Property parentConversation = message.addLongProperty("parent")
    .getProperty();
message.addToOne(conversation, parentConversation);
conversation.addToMany(message, parentConversation);

Answer 2

conv.getMessageList returns just a java list. adding a message there will not save it to database. you need to save message to database via messageDao.

Answer 3

Just a guess: is your conversation persisted before calling msg.setConversation(conv)? Make sure by introducing a sanity check:

Conversation conv = getConversation();
if(conv.getId() == null) {
    throw new RuntimeException("Conversation not persisted: " + conv);
}
Message msg = new Message();
msg.setConversation(conv);
MessageDao.insert(msg); // Breakpoint here, is parentConversation set?
conv.resetMessageList();

If that's the issue, you must make sure that your conversation is persisted, e.g. by calling conversationDao.insertOrReplace(conv).

Once that works, you can also consider replacing conv.resetMessageList() with this line:

conv.getMessages().add(msg); // Keep same list, also more efficient

If that does not help, please debug it and check if msg has parentConversation set before it is inserted (see comment in the code).