kotlin-exposed-patterns

Exposed offers two styles: the DSL style uses Table.selectAll().where { } for direct SQL-like expressions, while the DAO style uses entity classes like UserEntity.find { } for lifecycle-managed objects. Wrap all operations in newSuspendedTransaction for coroutine safety.

Use the DSL style for simple, direct queries where you map ResultRow objects manually. Use the DAO style when you need entity lifecycle management, relationships via referrersOn, and property delegation to table columns.

Configure Flyway with your JDBC URL and credentials, point it to classpath:db/migration, and call migrate() at application startup before connecting Exposed. Versioned SQL files like V1__create_users.sql keep the schema in sync.

Yes, Exposed provides newSuspendedTransaction, which runs database operations inside a coroutine-safe transaction block. All suspend repository functions should use it instead of the blocking transaction function.

Connect Exposed to an in-memory H2 database with PostgreSQL compatibility mode, create tables with SchemaUtils.create, and clean data between tests with deleteAll. This lets repository tests run without external infrastructure.

Define a custom jsonb column type using registerColumn with a ColumnType that serializes values via kotlinx.serialization and wraps them in PGobject. The column can then be declared nullable on any table.