Get a Room

All About the Annotations

• @Entity models your tables
• @DAO defines your data access API
• @Database defines your, um, database

Relations

• @ForeignKey declares your foreign keys (surprise!)
• By default, that's it
  • No automatic retrieval of related objects
  • No collection accessors generated for you
  • Why? To make it easier to keep I/O on a background thread
• @Relation used to kinda fake ORM APIs a bit

Type Massaging

• @TypeConverter: convert objects to/from supported column types
• @Embedded: convert batch of columns into an object, embedded in an entity or other object

Transactions

• Default is typical: every DAO method is its own transaction
• Use @Transaction
  • On a DAO method that calls other DAO methods
  • On a @Query that returns a @Relation
  • On a @Query that might return > 1MB of data

Threading

• Default: everything is synchronous, you handle threading yourself
• @Query Reactive Options
  • Return a LiveData or something from RxJava (Observable, Single, etc.)
  • Both return objects immediately, queries performed once you observe

Security

• By default, everything stored in plaintext
• CWAC-SafeRoom
  • Attaches SQLCipher for Android to Room
  • You supply passphrase, ideally Editable straight from EditText
  • One-liner plus a dependency to integrate

Questions?