JAKO: Just Another Kotlin Orm (PostgreSQL)

Alessio

Last update: May 27, 2022

Related tags

Overview

JAKO: Just Another Kotlin Orm (PostgreSQL)

JAKO is a simple, minimal, no-dependency library to build and execute postgresql statements using a fluent dsl.

Main features:

Easy to use
Statement builders totally independent of execution
Easy to use custom connectors (like HikariCP or others)
No need to define table structures
RawStatement class in order to execute not yet supported SQL syntax
fluent transactions

Add JAKO to your project

Gradle

Add JitPack in your root build.gradle at the end of repositories:

repositories {
    maven { url 'https://jitpack.io' }
}

Add the dependency along with postgresql driver

dependencies {
    implementation 'org.postgresql:postgresql:42.3.3'
    implementation 'com.github.AlessioCoser:jako:0.0.9'
}

Maven

Add the JitPack repository to your build file

<repositories>
    <repository>
        <id>jitpack.ioid>
        <url>https://jitpack.iourl>
    repository>
repositories>

Add the dependency along with postgresql driver

<dependency>
    <groupId>org.postgresqlgroupId>
    <artifactId>postgresqlartifactId>
    <version>42.3.3version>
dependency>
<dependency>
    <groupId>com.github.AlessioCosergroupId>
    <artifactId>jakoartifactId>
    <version>0.0.9version>
dependency>

Getting Started

Build

Query

?) println(query.params()) // [Milano, 3]">

val query = Query.from("users")
    .join("pets" ON "pets.owner" EQ "users.id")
    .where(("city" EQ "Milano") AND ("age" GT 3))

println(query.toString())
// SELECT * FROM "users" INNER JOIN "pets" ON "pets"."owner" = "users"."id" WHERE ("city" = ? AND "age" > ?)
println(query.params())
// [Milano, 3]

Insert

val insert = Insert.into("users")
    .set("id", 1)
    .set("name", "Mario")
    .set("city", "Milano")
    .set("age", 30)

println(insert.toString())
// INSERT INTO "users" ("id", "name", "city", "age") VALUES (?, ?, ?, ?)
println(insert.params())
// [1, Mario, Milano, 30]

Update

val update = Update.table("users")
    .set("age", 31)
    .where("id" EQ 1)

println(update.toString())
// UPDATE "users" SET "age" = ? WHERE "id" = ?
println(update.params())
// [31, 1]

Delete

val delete = Delete.from("users")
    .where("id" EQ 1)

println(insert.toString())
// DELETE FROM "users" WHERE "id" = ?
println(insert.params())
// [1]

Execute

Query

Select all id fields from users as Ints.

= db.select(query).all { int("id") }">

val db = Database.connect("jdbc:postgresql://localhost:5432/database?user=user&password=password")
val query = Query.from("users")

val tableIds: List<Int> = db.select(query).all { int("id") }

Select first id as Int from users.

val db = Database.connect("jdbc:postgresql://localhost:5432/database?user=user&password=password")
val query = Query.from("users")

val tableIds: Int? = db.select(query).first { int("id") }

Another Statement

val db = Database.connect("jdbc:postgresql://localhost:5432/database?user=user&password=password")
val insert = Insert
    .into("customers")
    .set("name", "Carlo")
    .set("age", 18)

db.execute(insert)

Raw Statement

Use RawStatement for SQL syntax not yet supported by the library.

val db = Database.connect("jdbc:postgresql://localhost:5432/database?user=user&password=password")
val query = RawStatement("""SELECT "id" FROM "users" WHERE "city" = ?""", listOf("Milano"))

val tableIds: Int? = db.select(query).first { int("id") }

Execute statements in Transaction

Using useTransaction method you can run all db execute safely. When something goes wrong and an execution throws an exception the changes are automatically rollbacked.

val db = Database.connect("jdbc:postgresql://localhost:5432/database?user=user&password=password")

db.useTransaction {
    db.execute(Insert.into("users").set("name", "Mario"))
    db.execute(Insert.into("users").set("name", "Paolo"))
    db.execute(Insert.into("users").set("name", "Carlo"))
}

Custom Connectors

If you create a database instance without a custom connector the library use a SimpleConnector which adopt the standard DriverManager.getConnection() method to get a new database connection.

val db = Database.connect("jdbc:postgresql://localhost:5432/tests?user=user&password=password")

If you want to use this library in production we recommend to use a CustomConnector so you can use your connection pool/cache library.

So you have to create a database instance in this way:

val customConnector: DatabaseConnector = MyCustomConnector("jdbc:postgresql://localhost:5432/tests?user=user&password=password")
val db = Database.connect(customConnector)

In the example below we will create a Connector for HikariCP

HikariCP Custom Connector Example

1. Add HikariCP to the project dependencies

Add to dependencies:

"com.zaxxer:HikariCP:4.0.3"
// for java 11 compatibility use the version 5.0.1

2. Create the custom Connector

class HikariConnector(jdbcUrl: String, poolSize: Int = 10) : DatabaseConnector {
    private val dataSource = HikariDataSource().also {
        it.driverClassName = "org.postgresql.Driver"
        it.jdbcUrl = jdbcUrl
        it.maximumPoolSize = poolSize 
        // start with this: ((2 * core_count) + number_of_disks)
    }

    override fun connection(): Connection {
        return dataSource.connection
    }
}

3. Use it

val customConnector: DatabaseConnector = HikariConnector("jdbc:postgresql://localhost:5432/tests?user=user&password=password")
val db = Database.connect(customConnector)

lightweight and minimalist ORM for Java/Android. works with SQLite & MySQL. (not actively maintained)

Description ORMAN is an minimalistic and lightweight ORM framework for Java which can handle your common database usage without writing SQL and strugg

246 Nov 20, 2022

An ORM for Android with type-safety and painless smart migrations

Android Orma Orma is a ORM (Object-Relation Mapper) for Android SQLiteDatabase. Because it generates helper classes at compile time with annotation pr

440 Nov 25, 2022

Performance comparison of Android ORM Frameworks

Performance comparison of Android ORM Frameworks At the moment there are a lot of ORM-libraries for the Android OS. We reviewed the most popular ones

328 Dec 21, 2022

Kotlin-Exposed-SQL - Example of using Exposed with Kotlin for the consumption of relational SQL Databases

Kotlin Exposed SQL Sencillo ejemplo sobre el uso y abuso de Exposed ORM de Jetbr

3 Jun 14, 2022

requery - modern SQL based query & persistence for Java / Kotlin / Android

A light but powerful object mapping and SQL generator for Java/Kotlin/Android with RxJava and Java 8 support. Easily map to or create databases, perfo

3.1k Dec 29, 2022

A Java/Kotlin library for Android platform, to manage bean's persistence in SQLite, SharedPreferences, JSON, XML, Properties, Yaml, CBOR.

Thanks to JetBrains for support Kripton Persistence Library project! Kripton Persistence Library Kripton is a java library, for Android platform, that