Exposed

Exposed is the SQL framework used by every Arda backend service for PostgreSQL persistence. It is chosen for its idiomatic Kotlin DSL, type safety, and explicit transaction scoping — properties that align with Arda’s bitemporal persistence model and AppError contract.

• Version: 0.60.0.
• Database: PostgreSQL (production); ContainerizedPostgres test fixture for unit/integration tests.
• Repositories: operations/, accounts-component/, common-module/ (shared Table definitions and converters).

Conventions in this codebase

• DAO layer is not used. Exposed’s “DSL” API is the only API in use. Per-table Table objects describe schema; queries use select, insert, update against those.
• Transactions are explicit. Every database access is wrapped in a transaction(database) { ... } block at a well-defined boundary (typically a use case or service method). No implicit “request transaction”.
• Bitemporal columns (valid_from, valid_to, tx_from, tx_to) are part of every business-state table. See Bitemporal Persistence.
• Schema migrations are owned by Flyway, not Exposed. Exposed describes the current schema; Flyway migrations under db/migration/ evolve it.
• Error handling: SQL errors are caught at the boundary and mapped to the AppError sealed hierarchy. See Exception Handling.

UpdateBuilder.set has no already-initialized guard

In Exposed 0.60.0, UpdateBuilder.set ends in a plain values[column] = value. Setting the same column twice in one statement does not warn and does not fail — the last write wins, silently.

That matters wherever two writers can reach one column: a framework populating an envelope and a hand-written fill body populating the same column will both succeed, and which value lands depends on call order rather than on intent.

Where a column has more than one possible writer, make one of them the only one. Where that is not possible, assert the column’s value after the statement rather than trusting that the intended writer ran last.

Authoritative references

• Exposed documentation — official.
• Exposed wiki on GitHub — deeper reference for the DSL and Table API.

See also

• Kotlin Coding Standards — Result handling and AppError patterns applied at every Exposed boundary; see Persistence and Transactions for the Universe-vs-plain-table decision and the DBIO transaction contract.
• The unit-tests-infra skill — ContainerizedPostgres and the Harness pattern for database-backed tests.
• Data Authority Pattern — module boundary rules around shared tables.