stack-kotlin-exposed-patterns

name	stack-kotlin-exposed-patterns
description	Kotlin JetBrains Exposed ORM framework — DAO, DSL, transactions
license	Apache-2.0
metadata	{"author":"manuel-retamozo-garcia","version":"1.0"}
capabilities	["kotlin"]

Kotlin Exposed Patterns

Comprehensive patterns for database access with JetBrains Exposed ORM, including DSL queries, DAO, transactions, and production-ready configuration.

When to Use

• Setting up database access with Exposed
• Writing SQL queries using Exposed DSL or DAO
• Configuring connection pooling with HikariCP
• Creating database migrations with Flyway
• Implementing the repository pattern with Exposed
• Handling JSON columns and complex queries

Core Rules

1. Exposed Query Styles: Use DSL for direct SQL-like expressions (explicit control) and DAO for entity lifecycle management.
2. Transaction Safety: All database operations must run inside newSuspendedTransaction blocks for coroutine safety and atomicity. Explicitly define transaction isolation levels (e.g. TRANSACTION_READ_COMMITTED) when required.
3. Connection Pooling: Always configure connection pooling via HikariCP, setting isAutoCommit = false and validating settings.
4. Database Migrations: Manage database schemas with Flyway versioned migrations (classpath:db/migration), running them on application startup.
5. Testing Isolation: Use an in-memory H2 database (jdbc:h2:mem:test) for tests, running them within transactions and deleting all records inside beforeTest.

References

For full code examples, table definitions, join queries, batch operations, JSONB serialization mapping, and testing repositories, refer to:

• JetBrains Exposed ORM Patterns & Examples