repository·main·Indexed 27 days ago
https://github.com/jetbrains/exposedA lightweight SQL library for Kotlin providing a typesafe DSL and a DAO API. It supports both JDBC and R2DBC drivers, enabling seamless database engine switching. The library includes integration with Spring Boot via ExposedAutoConfiguration and a Gradle plugin for generating migration scripts.
Exposed is a lightweight SQL library for Kotlin that provides two distinct approaches for database access:
It supports both JDBC and R2DBC (reactive) drivers, allowing you to switch between different database engines with minimal changes.
This project implements a project-issue tracker using Domain-Driven Design (DDD) to separate the following domains: User, Project, Issue, and Comment.
Key components for the Issue domain include:
IssuesTable.kt: Defines the Exposed table object and converters.IssueRepository.kt: Contains the Exposed database operations.IssueService.kt: Handles service-level logic.IssueRoutes.kt: Manages Ktor route handlers.Database connection and schema setup are configured in plugins/Database.kt.
Exposed provides several sample projects demonstrating different integration patterns and use cases:
exposed-ktor: A backend application implementing CRUD (Create, Read, Update, Delete) endpoints using Ktor and Exposed.exposed-ktor-r2dbc: A backend application using Ktor, Exposed, and PostgreSQL R2DBC.exposed-spring: A Spring Boot 3 based project demonstrating CRUD operations.exposed-migration: An application illustrating how to generate migration scripts using Exposed.exposed-gradle-plugin-sample: A project demonstrating the use of the Exposed Gradle plugin and its generateMigrations task.The Exposed-Ktor sample project demonstrates how to integrate Exposed with a Ktor backend for CRUD operations. The core logic is split into two main components:
UsersSchema.kt defines the database structure using Exposed's DSL.Databases.kt implements the backend logic and provides various endpoints to perform Create, Read, Update, and Delete operations.In version 1.0.0, the exec() method now accepts a BlockingExecutable instead of a Statement.
Handling Query Results:
exec(query), the lambda argument is wrapped in a ResultApi. To access the underlying java.sql.ResultSet, you must cast it: (it as JdbcResult).result.java.sql.ResultSet directly, use execQuery(query) instead. This is recommended for explain() or DML functions like .insertReturning().// Option 1: Using exec() with manual casting
transaction {
val query = TableA.select(TableA.amount).where { TableA.amount greater 100 }
val result = exec(query) {
val rs = (it as JdbcResult).result
// process rs
}
}
// Option 2: Using execQuery() to get ResultSet directly (Recommended)
transaction {
val query = TableA.select(TableA.amount).where { TableA.amount greater 100 }
val result = execQuery(query) {
val amounts = mutableListOf<Int>()
while (it.next()) {
amounts += it.getInt("amount")
}
amounts
}
}To run the provided Spring Boot sample project, execute the Gradle wrapper command from the repository's root directory. Once running, you can test the available endpoints using the provided requests.http file.
./gradlew bootRunOnce the catalog is imported, you can reference Exposed modules in your dependencies block using type-safe accessors. The accessor is generated by removing the exposed- prefix and converting dashes into nested accessors.
dependencies {
implementation(exposedLibs.core)
implementation(exposedLibs.jdbc)
implementation(exposedLibs.kotlin.datetime)
}The sample project provides Gradle tasks to automate the migration workflow:
./gradlew generateMigrationScript from the repository root../gradlew run from the repository root../gradlew generateMigrationScript
./gradlew runExposed version 1.0.0 maintains compatibility with Spring Boot 3 via exposed-spring-boot-starter.
If you are migrating to Spring Boot 4 (Spring Framework 7), you must replace exposed-spring-boot-starter with exposed-spring-boot4-starter. This also requires updating the import path for ExposedAutoConfiguration to the v1.spring.boot4 package.
// For Spring Boot 4 migration
dependencies {
implementation("org.jetbrains.exposed:exposed-spring-boot4-starter:1.0.0")
}
// Updated imports for Spring Boot 4
import org.jetbrains.exposed.v1.spring.boot4.autoconfigure.ExposedAutoConfiguration
import org.springframework.boot.autoconfigure.ImportAutoConfiguration
import org.springframework.boot.autoconfigure.SpringBootApplication
@SpringBootApplication
@ImportAutoConfiguration(ExposedAutoConfiguration::class)
class SpringApplicationThe SqlExpressionBuilder object is deprecated in version 1.0.0. Most expression builder methods have been moved to top-level functions.
To resolve errors in lambda blocks (like those in update or where), you must now explicitly import the required top-level functions (e.g., import org.jetbrains.exposed.v1.core.and, import org.jetbrains.exposed.v1.core.eq, etc.) or use a wildcard import like import org.jetbrains.exposed.v1.core.*.
spring-transaction (Spring Framework 6)spring7-transaction (Spring Framework 7)exposed-spring-boot-starter (Spring Boot 3)exposed-spring-boot4-starter (Spring Boot 4)exposed-crypt (Spring Security 7)exposed-r2dbcexposed-migration-r2dbcDepending on your Spring Boot version, add the corresponding starter to your build script:
org.jetbrains.exposed:exposed-spring-boot4-starter. This includes the latest Exposed version, SpringTransactionManager, and spring-boot-starter-jdbc.org.jetbrains.exposed:exposed-spring-boot-starter.Note: Support for Spring Boot 3 will be removed in the next major Exposed release.