Local DB Design Patterns — Room + Repository + ViewModel Architecture

Local DB Design Patterns — Room + Repository + ViewModel Architecture Master the Room database architecture with Repository pattern and reactive ViewModel. This guide covers entity design, DAO patterns, and state management for robust offline-first Android apps. Entity Design with Room Define your database schema using @entity annotation: \ `kotlin // User entity with primary key and indices @entity ( tableName = "users", indices = [Index(value = ["email"], unique = true)] ) data class UserEntity( @PrimaryKey(autoGenerate = true) val id: Long = 0, val name: String, val email: String, val createdAt: Long = System.currentTimeMillis() ) // Post entity with foreign key constraint @entity ( tableName = "posts", foreignKeys = [ ForeignKey( entity = UserEntity::class, parentColumns = ["id"], childColumns = ["userId"], onDelete = ForeignKey.CASCADE ) ], indices = [ Index(value = ["userId"]), Index(value = ["createdAt"]) ] ) data class PostEntity( @PrimaryKey(autoGenerate = true) val id: Long =