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jOOQ and Kotlin
Applies to ✅ Open Source Edition ✅ Express Edition ✅ Professional Edition ✅ Enterprise Edition
As any other library, jOOQ can be easily used in Kotlin, taking advantage of the many Kotlin language features such as for example:
- Optional ";" at the end of a Kotlin statement
- Type inference for local variables
A short example jOOQ application in Kotlin might look like this:
package org.jooq.example.kotlin import java.util.Properties import org.jooq.* import org.jooq.impl.DSL import org.jooq.impl.DSL.* import org.jooq.example.db.h2.Tables.* fun main(args: Array<String>) { val properties = Properties(); properties.load(Properties::class.java.getResourceAsStream("/config.properties")); DSL.using( properties.getProperty("db.url"), properties.getProperty("db.username"), properties.getProperty("db.password") ).use { ctx -> val a = AUTHOR val b = BOOK ctx.select(a.FIRST_NAME, a.LAST_NAME, b.TITLE) .from(a) .join(b).on(a.ID.eq(b.AUTHOR_ID)) .orderBy(1, 2, 3) .forEach { println("${it[b.TITLE]} by ${it[a.FIRST_NAME]} ${it[a.LAST_NAME]}") } } }
Note that Kotlin supports some means of operator overloading. For instance, a + b
in Kotlin maps to a formal a.plus(b)
method invocation, and jOOQ provides the required synonyms in its API to help you write such expressions.
One particularly nice language feature is the fact that [square brackets] allow for accessing any object's contents via get()
and set()
methods. Instead of using the above value1()
, value2()
, and value3()
methods, we could also iterate as such:
ctx.select(AUTHOR.FIRST_NAME, AUTHOR.LAST_NAME, BOOK.TITLE) .from(AUTHOR) .join(BOOK).on(AUTHOR.ID.eq(BOOK.AUTHOR_ID)) .orderBy(1, 2, 3) .forEach { println("${it[BOOK.TITLE]} by ${it[AUTHOR.FIRST_NAME]} ${it[AUTHOR.LAST_NAME]}") // Notice: ^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^ }
A caveat of Kotlin operator overloading is the fact that operators such as ==
or >=
map to a.equals(b)
, a.compareTo(b) == 0
, a.compareTo(b) >= 0
respectively. This behaviour does not make sense in a fluent API such as jOOQ.
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