（ORMLite-android）直接设置外键字段

Question

In my android app, I pull down record from the server and save them to the db - I'd like to be able to save "Message" records without having to first save the "Thread" records that they are attached to.

A message is composed of:

• String id
• String body
• Long sent_ts
• String sender_id
• String topic_id

Is it possible to set the topic_id and sender_id records directly on a Message object rather than creating a dummy Topic instance and User instance? I know that I can either not mark the fields as foreign and give up on some easier lookups of related objects or save all nested objects first, but is it possible to just directly set the foreign key references in the case that the keys are externally provided?

This is being done on Android with the standard Android SQLite setup.

EDIT

I finally settled on writing multiple models on the same database table. It's not the most elegant solution, but it seemed the only way to be able to either populate the foreign id fields directly or join on other tables, depending on the context.

Answer 1

I'd like to be able to save "Message" records without having to first save the "Thread" records that they are attached to.

So each Message has a foreign Topic and User fields, and you'd like to persist the Message instances before you've assigned them to those foreign objects?

Yes, you can certainly leave your topic and user fields to be null . You will need to mark them as canBeNull=true of course. Then later you should be able to set the topic or user fields on the Message in question and then call messageDao.update(message) to update the database.

Edit:

After reading your comments I now understand. Is there a way to just save the id fields onto a class instead of creating dummy objects that just have the id field set? There answer is no unless you do raw SQL create statement yourself. ORMLite needs to have a Topic field because that's what it is expecting. If you just want the id then you can have a int topic_id field instead of Topic topic and do the topic association yourself.