Connect an application

Prerequisites

This tutorial assumes that you have:

  • installed YugabyteDB, created a universe and are able to interact with it using the YCQL shell. If not, follow these steps in Quick start.
  • installed Scala version 2.12 or later.
  • installed sbt 1.3.8 or later.

sbt

To build a Scala application using the Yugabyte Java Driver for YCQL, you must add the following sbt (Scala build tool) dependency to your application:

libraryDependencies += "com.yugabyte" % "cassandra-driver-core" % "3.8.0-yb-5"

Create the sbt build file

Create a sbt build file build.sbt and copy the following content into it.

name := "YBCqlHelloWorld"
version := "1.0"
scalaVersion := "2.12.11"
scalacOptions := Seq("-unchecked", "-deprecation")

// https://mvnrepository.com/artifact/com.yugabyte/cassandra-driver-core
libraryDependencies += "com.yugabyte" % "cassandra-driver-core" % "3.8.0-yb-5"

Write a sample Scala application

Copy the following contents into the file YBCqlHelloWorld.scala.

package com.yugabyte.sample.apps

import com.datastax.driver.core.Cluster
import com.datastax.driver.core.ResultSet
import com.datastax.driver.core.Row
import com.datastax.driver.core.Session


object YBCqlHelloWorld {

  def main(args: Array[String]): Unit = {
    try {
      // Create a Cassandra client.
      val cluster = Cluster.builder.addContactPoint("127.0.0.1").build
      val session = cluster.connect

      // Create keyspace 'ybdemo' if it does not exist.
      val createKeyspace = "CREATE KEYSPACE IF NOT EXISTS ybdemo;";
      val createKeyspaceResult = session.execute(createKeyspace);
      println("Created keyspace ybdemo");

      // Create table 'employee' if it does not exist.
      val createTable = """
        CREATE TABLE IF NOT EXISTS ybdemo.employee (
          id int PRIMARY KEY,
          name varchar,
          age int,
          language varchar
        );
      """
      val createResult = session.execute(createTable)
      println("Created table employee")

      // Insert a row.
      val insert = """
        INSERT INTO ybdemo.employee
        |(id, name, age, language)
        |VALUES
        |(1, 'John', 35, 'Scala');
        """.trim.stripMargin('|').replaceAll("\n", " ")
      val insertResult = session.execute(insert)
      println(s"Inserted data: ${insert}")

      // Query the row and print out the result.
      val select = """
        SELECT name, age, language
         FROM  ybdemo.employee
         WHERE id = 1;
      """
      val rows = session.execute(select).all
      val name = rows.get(0).getString(0)
      val age = rows.get(0).getInt(1)
      val language = rows.get(0).getString(2)
      println(
        s"""
          Query returned ${rows.size}
          |row: name=${name},
          |age=${age},
          |language=${language}
        """.trim.stripMargin('|').replaceAll("\n", " ")
      )

      // Close the client.
      session.close
      cluster.close
    } catch {
      case e: Throwable => println(e.getMessage)
    }

  } //  def main

} // object YBCqlHelloWorld

Build and run the application

To build the application, just run the following command.

$ sbt compile

To run the program, run the following command.

$ sbt run

You should see the following as the output.

Created keyspace ybdemo
Created table employee
Inserted data: INSERT INTO ybdemo.employee (id, name, age, language) VALUES (1, 'John', 35, 'Scala');
Query returned 1 row: name=John, age=35, language=Scala