Kotlin Exposed Framework Tutorial 🎯

Welcome to the Kotlin Exposed Framework tutorial! This guide is designed to help both beginners and intermediates learn this powerful database access library for Kotlin.

What is Kotlin Exposed Framework? 📝

Kotlin Exposed is an Object-Relational Mapping (ORM) library that simplifies the process of interacting with databases in Kotlin applications. It offers a clean and concise syntax, making it easier to work with SQL databases.

Why Use Kotlin Exposed? 💡

Ease of Use: Exposed provides a simpler, more Kotlin-friendly API compared to traditional JDBC or SQLite drivers.
Type Safety: Exposed ensures type safety when working with databases, reducing the risk of runtime errors.
SQL Generation: Exposed generates SQL queries on the fly, making your code more maintainable and less prone to errors.

Setting Up Kotlin and Exposed 📝

First, make sure you have Kotlin installed on your system. You can download it from here.
Add the Exposed dependency to your project's build.gradle file:

gradle

dependencies {
    implementation "org.jetbrains.exposed:exposed-core:$(exposed_version)"
    implementation "org.jetbrains.exposed:exposed-sqlite-jdbc:$(exposed_version)"
}

Replace $(exposed_version) with the appropriate Exposed version.

Basic CRUD Operations 📝

Let's create a simple User table and perform basic CRUD operations:

kotlin

import org.jetbrains.exposed.sql.*
import org.jetbrains.exposed.sql.transactions.transaction

object Users : Table() {
    val id = integer("id").autoIncrement().primaryKey()
    val name = varchar("name", 255)
    val email = varchar("email", 255).uniqueIndex()
}

fun main() {
    transaction {
        // Create table
        Users.createTable()

        // Insert a new user
        Users.insert {
            it[name] = "John Doe"
            it[email] = "john.doe@example.com"
        }
    }

    transaction {
        // Fetch all users
        val users = Users.selectAll().map { row -> User(row[Users.id]!!, row[Users.name]!!, row[Users.email]!!) }

        // Update a user
        Users.update({ Users.id eq 1 }) {
            it[name] = "Jane Doe"
            it[email] = "jane.doe@example.com"
        }

        // Delete a user
        Users.deleteWhere { Users.id eq 1 }
    }
}

data class User(val id: Int, val name: String, val email: String)

Quiz 📝

This tutorial will continue with more advanced topics such as relationships, queries, and migrations. Stay tuned! 🎯