AttributeCollection

Collection attributes provide basic support for one-to-many relationships. For example, Threads in N1 have a collection of Labels or Folders.

When Collection attributes are marked as queryable, the RxDatabase automatically creates a join table and maintains it as you create, save, and delete models. When you call persistModel, entries are added to the join table associating the ID of the model with the IDs of models in the collection.

Collection attributes have an additional clause builder, contains:

db.findAll(Thread).where([Thread.attributes.categories.contains('inbox')])

This is equivalent to writing the following SQL:

SELECT `Thread`.`data` FROM `Thread`
INNER JOIN `ThreadLabel` AS `M1` ON `M1`.`id` = `Thread`.`id`
WHERE `M1`.`value` = 'inbox'
ORDER BY `Thread`.`last_message_received_timestamp` DESC

The value of this attribute is always an array of other model objects.

Section: Database