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## Welcome to **Exposed**, an ORM framework for [Kotlin](https://github.com/JetBrains/kotlin).
[Exposed](https://www.jetbrains.com/exposed/) is a lightweight SQL library on top of a database connectivity driver for the Kotlin programming language,
with support for both JDBC and R2DBC (since version 1.0.0-*) drivers.
It offers two approaches for database access: a typesafe SQL-wrapping Domain-Specific Language (DSL) and a lightweight Data Access Object (DAO) API.
Our official mascot is the cuttlefish, which is well-known for its outstanding mimicry ability that enables it to blend seamlessly into any environment.
Similar to our mascot, Exposed can be used to mimic a variety of database engines, which helps you to build applications without dependencies on any specific database engine and to switch between them with very little or no changes.
## Supported Databases
- H2 (versions 2.x)
- [](https://github.com/mariadb-corporation/mariadb-connector-j)
- [](https://github.com/mysql/mysql-connector-j)
- [](https://www.oracle.com/ca-en/database/technologies/appdev/jdbc-downloads.html)
- [](https://jdbc.postgresql.org/)
(Also, PostgreSQL using the [pgjdbc-ng](https://impossibl.github.io/pgjdbc-ng/) JDBC driver)
- [](https://docs.aws.amazon.com/redshift/latest/mgmt/jdbc20-install.html) (JDBC only)
- [](https://github.com/microsoft/mssql-jdbc)
- [](https://github.com/xerial/sqlite-jdbc)
## Dependencies
Releases of Exposed are available in the [Maven Central repository](https://search.maven.org/search?q=org.jetbrains.exposed).
For details on how to configure this repository and how to add Exposed dependencies to an existing Gradle/Maven project,
see the full [guide on modules](https://www.jetbrains.com/help/exposed/exposed-modules.html).
### Exposed modules
`Exposed` consists of the following core modules:
| Module | Function |
|---------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `exposed-core` | Provides the foundational components and abstractions needed to work with databases in a type-safe manner and includes the Domain-Specific Language (DSL) API |
| `exposed-dao` | (Optional) Allows you to work with the Data Access Object (DAO) API. <br> It is only compatible with `exposed-jdbc`; with `exposed-r2dbc`, use `exposed-dao-r2dbc` instead.</br> |
| `exposed-dao-r2dbc` | (Optional) Allows you to work with the Data Access Object (DAO) API over `exposed-r2dbc`. <br> It is an experimental preview, so its API may change between releases.</br> |
| `exposed-jdbc` | Provides support for Java Database Connectivity (JDBC) with a transport-level implementation based on the Java JDBC API |
| `exposed-r2dbc` | Provides support for Reactive Relational Database Connectivity (R2DBC) |
As well as the following extension modules:
| Module | Function |
|--------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `exposed-crypt` | Provides additional column types to store encrypted data in the database and encode/decode it on the client-side, as well as one-way hashed data such as passwords |
| `exposed-java-time` | Date-time extensions based on the [Java 8 Time API](https://docs.oracle.com/javase/8/docs/api/java/time/package-summary.html) |
| `exposed-jodatime` | Date-time extensions based on the [Joda-Time](https://www.joda.org/joda-time/) library |
| `exposed-json` | JSON and JSONB data type extensions |
| `exposed-kotlin-datetime` | Date-time extensions based on the [`kotlinx-datetime`](https://kotlinlang.org/api/kotlinx-datetime/) library |
| `exposed-migration-core` | Provides core common functionality for database schema migrations |
| `exposed-migration-jdbc` | Provides utilities to support database schema migrations, with a reliance on a JDBC driver |
| `exposed-migration-r2dbc` | Provides utilities to support database schema migrations, with a reliance on a R2DBC driver |
| `exposed-money` | Extensions to support [`MonetaryAmount`](https://javamoney.github.io/apidocs/java.money/javax/money/MonetaryAmount.html) from the [JavaMoney API](https://javamoney.github.io/) |
| `exposed-spring-boot-starter` | A starter for [Spring Boot 3](https://spring.io/projects/spring-boot) to utilize Exposed as the ORM |
| `exposed-spring-boot4-starter` | A starter for [Spring Boot 4](https://spring.io/projects/spring-boot) to utilize Exposed as the ORM |
| `spring-transaction` | Transaction manager that builds on top of the standard transaction workflow from Spring Framework 6 |
| `spring7-transaction` | Transaction manager that builds on top of the standard transaction workflow from Spring Framework 7 |
### Requirements
Kotlin version 2.2.+
The following module(s) require JDK 17 or newer:
* `spring-transaction` - depends on Spring Framework 6
* `spring7-transaction` - depends on Spring Framework 7
* `exposed-spring-boot-starter` - depends on Spring Boot 3
* `exposed-spring-boot4-starter` - depends on Spring Boot 4
* `exposed-crypt` - depends on Spring Security 7
The following module(s) require JDK 11 or newer:
* `exposed-r2dbc`
* `exposed-migration-r2dbc`
All other modules have a minimum requirement of JDK 8.
## Samples using Exposed
Follow the [Getting Started with DSL tutorial](https://www.jetbrains.com/help/exposed/getting-started-with-exposed.html) for a quick start or check out the [samples](samples/README.md) for more in-depth projects.
## Documentation
For complete documentation, samples, and tutorials, see the following links:
- [Documentation](https://www.jetbrains.com/help/exposed/home.html)
- [Migration Guide](https://www.jetbrains.com/help/exposed/migration-guide-1-0-0.html)
- [Breaking changes](https://www.jetbrains.com/help/exposed/breaking-changes.html)
## Contributing
### Reporting issues
We encourage your feedback in any form, such as feature requests, bug reports, documentation updates, and questions.
Please use [our issue tracker](https://youtrack.jetbrains.com/issues/EXPOSED) to report any issues or to log new requests.
While issues are visible publicly, either creating a new issue or commenting on an existing one does require logging in to YouTrack.
### Submitting pull requests
We actively welcome your pull requests and encourage you to link your work to an [existing issue](https://youtrack.jetbrains.com/issues/EXPOSED).
See the full [contribution guide](https://www.jetbrains.com/help/exposed/contributing.html#pull-requests) for more details.
By contributing to the Exposed project, you agree that your contributions will be licensed under [Apache License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0).
<br><br>
## Support
Have questions or want to contribute to the discussion? Join us in the [#exposed](https://kotlinlang.slack.com/messages/exposed/) channel on the [Kotlin Slack](https://kotlinlang.slack.com/).
If you're not a member yet, you can [request an invitation](https://surveys.jetbrains.com/s3/kotlin-slack-sign-up).
## Examples
### SQL DSL
```kotlin
import org.jetbrains.exposed.v1.core.*
import org.jetbrains.exposed.v1.core.SqlExpressionBuilder.like
import org.jetbrains.exposed.v1.jdbc.*
import org.jetbrains.exposed.v1.jdbc.transactions.transaction
object Cities : Table() {
val id = integer("id").autoIncrement()
val name = varchar("name", 50)
override val primaryKey = PrimaryKey(id)
}
object Users : Table() {
val id = varchar("id", 10)
val name = varchar("name", length = 50)
val cityId = integer("city_id").references(Cities.id).nullable()
override val primaryKey = PrimaryKey(id, name = "PK_User_ID")
}
fun main() {
Database.connect("jdbc:h2:mem:test", driver = "org.h2.Driver", user = "root", password = "")
transaction {
addLogger(StdOutSqlLogger)
SchemaUtils.create(Cities, Users)
val saintPetersburgId = Cities.insert {
it[name] = "St. Petersburg"
} get Cities.id
val munichId = Cities.insert {
it[name] = "Munich"
} get Cities.id
val pragueId = Cities.insert {
it.update(name, stringLiteral(" Prague ").trim().substring(1, 2))
}[Cities.id]
val pragueName = Cities
.selectAll()
.where { Cities.id eq pragueId }
.single()[Cities.name]
println("pragueName = $pragueName")
Users.insert {
it[id] = "andrey"
it[name] = "Andrey"
it[cityId] = saintPetersburgId
}
Users.insert {
it[id] = "sergey"
it[name] = "Sergey"
it[cityId] = munichId
}
Users.insert {
it[id] = "eugene"
it[name] = "Eugene"
it[cityId] = munichId
}
Users.insert {
it[id] = "alex"
it[name] = "Alex"
it[cityId] = null
}
Users.insert {
it[id] = "smth"
it[name] = "Something"
it[cityId] = null
}
Users.update(where = { Users.id eq "alex" }) {
it[name] = "Alexey"
}
Users.deleteWhere { Users.name like "%thing" }
println("All cities:")
Cities
.selectAll()
.forEach { result ->
println("${result[Cities.id]}: ${result[Cities.name]}")
}
println("Manual join:")
(Users innerJoin Cities)
.select(Users.name, Cities.name)
.where {
(Users.id.eq("andrey") or Users.name.eq("Sergey")) and
Users.id.eq("sergey") and Users.cityId.eq(Cities.id)
}.forEach { result ->
println("${result[Users.name]} lives in ${result[Cities.name]}")
}
println("Join with foreign key:")
(Users innerJoin Cities)
.select(Users.name, Users.cityId, Cities.name)
.where { Cities.name.eq("St. Petersburg") or Users.cityId.isNull() }
.forEach { result ->
if (result[Users.cityId] != null) {
println("${result[Users.name]} lives in ${result[Cities.name]}")
} else {
println("${result[Users.name]} lives nowhere")
}
}
println("Functions and group by:")
(Cities innerJoin Users)
.select(Cities.name, Users.id.count())
.groupBy(Cities.name)
.forEach { result ->
val cityName = result[Cities.name]
val userCount = result[Users.id.count()]
if (userCount > 0) {
println("$userCount user(s) live(s) in $cityName")
} else {
println("Nobody lives in $cityName")
}
}
SchemaUtils.drop(Users, Cities)
}
}
```
Generated SQL:
```sql
SQL: CREATE TABLE IF NOT EXISTS CITIES (ID INT AUTO_INCREMENT PRIMARY KEY, "name" VARCHAR(50) NOT NULL)
SQL: CREATE TABLE IF NOT EXISTS USERS (ID VARCHAR(10), "name" VARCHAR(50) NOT NULL, CITY_ID INT NULL, CONSTRAINT PK_User_ID PRIMARY KEY (ID), CONSTRAINT FK_USERS_CITY_ID__ID FOREIGN KEY (CITY_ID) REFERENCES CITIES(ID) ON DELETE RESTRICT ON UPDATE RESTRICT)
SQL: INSERT INTO CITIES ("name") VALUES ('St. Petersburg')
SQL: INSERT INTO CITIES ("name") VALUES ('Munich')
SQL: INSERT INTO CITIES ("name") VALUES (SUBSTRING(TRIM(' Prague '), 1, 2))
SQL: SELECT CITIES.ID, CITIES."name" FROM CITIES WHERE CITIES.ID = 3
pragueName = Pr
SQL: INSERT INTO USERS (ID, "name", CITY_ID) VALUES ('andrey', 'Andrey', 1)
SQL: INSERT INTO USERS (ID, "name", CITY_ID) VALUES ('sergey', 'Sergey', 2)
SQL: INSERT INTO USERS (ID, "name", CITY_ID) VALUES ('eugene', 'Eugene', 2)
SQL: INSERT INTO USERS (ID, "name", CITY_ID) VALUES ('alex', 'Alex', NULL)
SQL: INSERT INTO USERS (ID, "name", CITY_ID) VALUES ('smth', 'Something', NULL)
SQL: UPDATE USERS SET "name"='Alexey' WHERE USERS.ID = 'alex'
SQL: DELETE FROM USERS WHERE USERS."name" LIKE '%thing'
All cities:
SQL: SELECT CITIES.ID, CITIES."name" FROM CITIES
1: St. Petersburg
2: Munich
3: Pr
Manual join:
SQL: SELECT USERS."name", CITIES."name" FROM USERS INNER JOIN CITIES ON CITIES.ID = USERS.CITY_ID WHERE ((USERS.ID = 'andrey') OR (USERS."name" = 'Sergey')) AND (USERS.ID = 'sergey') AND (USERS.CITY_ID = CITIES.ID)
Sergey lives in Munich
Join with foreign key:
SQL: SELECT USERS."name", USERS.CITY_ID, CITIES."name" FROM USERS INNER JOIN CITIES ON CITIES.ID = USERS.CITY_ID WHERE (CITIES."name" = 'St. Petersburg') OR (USERS.CITY_ID IS NULL)
Andrey lives in St. Petersburg
Functions and group by:
SQL: SELECT CITIES."name", COUNT(USERS.ID) FROM CITIES INNER JOIN USERS ON CITIES.ID = USERS.CITY_ID GROUP BY CITIES."name"
2 user(s) live(s) in Munich
1 user(s) live(s) in St. Petersburg
SQL: DROP TABLE IF EXISTS USERS
SQL: DROP TABLE IF EXISTS CITIES
```
### DAO
```kotlin
import org.jetbrains.exposed.v1.core.StdOutSqlLogger
import org.jetbrains.exposed.v1.core.dao.id.*
import org.jetbrains.exposed.v1.dao.*
import org.jetbrains.exposed.v1.jdbc.*
import org.jetbrains.exposed.v1.jdbc.transactions.transaction
object Cities: IntIdTable() {
val name = varchar("name", 50)
}
object Users : IntIdTable() {
val name = varchar("name", length = 50).index()
val city = reference("city", Cities)
val age = integer("age")
}
class City(id: EntityID<Int>) : IntEntity(id) {
companion object : IntEntityClass<City>(Cities)
var name by Cities.name
val users by User referrersOn Users.city
}
class User(id: EntityID<Int>) : IntEntity(id) {
companion object : IntEntityClass<User>(Users)
var name by Users.name
var city by City referencedOn Users.city
var age by Users.age
}
fun main() {
Database.connect("jdbc:h2:mem:test", driver = "org.h2.Driver", user = "root", password = "")
transaction {
addLogger(StdOutSqlLogger)
val saintPetersburg = City.new {
name = "St. Petersburg"
}
val munich = City.new {
name = "Munich"
}
User.new {
name = "Andrey"
city = saintPetersburg
age = 5
}
User.new {
name = "Sergey"
city = saintPetersburg
age = 27
}
User.new {
name = "Eugene"
city = munich
age = 42
}
val alex = User.new {
name = "alex"
city = munich
age = 11
}
alex.name = "Alexey"
println("Cities: ${City.all().joinToString { it.name }}")
println("Users in ${saintPetersburg.name}: ${saintPetersburg.users.joinToString { it.name }}")
println("Adults: ${User.find { Users.age greaterEq 18 }.joinToString { it.name }}")
SchemaUtils.drop(Users, Cities)
}
}
```
Generated SQL:
```sql
SQL: CREATE TABLE IF NOT EXISTS CITIES (ID INT AUTO_INCREMENT PRIMARY KEY, "name" VARCHAR(50) NOT NULL)
SQL: CREATE TABLE IF NOT EXISTS USERS (ID INT AUTO_INCREMENT PRIMARY KEY, "name" VARCHAR(50) NOT NULL, CITY INT NOT NULL, AGE INT NOT NULL, CONSTRAINT FK_USERS_CITY__ID FOREIGN KEY (CITY) REFERENCES CITIES(ID) ON DELETE RESTRICT ON UPDATE RESTRICT)
SQL: CREATE INDEX USERS_NAME ON USERS ("name")
SQL: INSERT INTO CITIES ("name") VALUES ('St. Petersburg')
SQL: INSERT INTO CITIES ("name") VALUES ('Munich')
SQL: SELECT CITIES.ID, CITIES."name" FROM CITIES
Cities: St. Petersburg, Munich
SQL: INSERT INTO USERS ("name", CITY, AGE) VALUES ('Andrey', 1, 5)
SQL: INSERT INTO USERS ("name", CITY, AGE) VALUES ('Sergey', 1, 27)
SQL: INSERT INTO USERS ("name", CITY, AGE) VALUES ('Eugene', 2, 42)
SQL: INSERT INTO USERS ("name", CITY, AGE) VALUES ('Alexey', 2, 11)
SQL: SELECT USERS.ID, USERS."name", USERS.CITY, USERS.AGE FROM USERS WHERE USERS.CITY = 1
Users in St. Petersburg: Andrey, Sergey
SQL: SELECT USERS.ID, USERS."name", USERS.CITY, USERS.AGE FROM USERS WHERE USERS.AGE >= 18
Adults: Sergey, Eugene
SQL: DROP TABLE IF EXISTS USERS
SQL: DROP TABLE IF EXISTS CITIES
```
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