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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();

    ).use { ctx ->
        val a = AUTHOR
        val b = BOOK

        ctx.select(a.FIRST_NAME, a.LAST_NAME, b.TITLE)
           .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:

           .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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