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Using Microsoft SQL Server with Scala Slick

Tuesday, May 01, 2018

This blog post shows simple CRUD operations on Microsoft SQL Server using Scala Slick version 3.2.3. You might be thinking what’s really great about it? Duh! But until Scala Slick 3.2.x was released, using commercial databases was within the horizon of an additional closed source package know as Slick Extensions which supported Slick drivers for following databases
  1. Oracle
  2. IBM DB2
  3. Microsoft SQL Server


Library dependency used for Slick Extensions
libraryDependencies += "com.typesafe.slick" %% "slick-extensions" % "3.0.0"
But with the newer version of Slick, i.e 3.2.x these drivers are now available within the Slick core package as open source release which can also be seen from the change log as well.
If you find yourself struggling with a setup to make Microsoft SQL Server work with Scala Slick in your project, maybe because of the lack of resources available on the web, then read up further :)

TL;DR

SQL Server database configurations
sqlserver = {
 driver = "slick.jdbc.SQLServerProfile$"
 db {
 host = ${?SQLSERVER_HOST}
 port = ${?SQLSERVER_PORT}
 databaseName = ${?SQLSERVER_DB_NAME}

 url = "jdbc:sqlserver://"${sqlserver.db.host}":"${sqlserver.db.port}";databaseName="${sqlserver.db.databaseName}
 user = ${?SQLSERVER_USERNAME}
 password = ${?SQLSERVER_PASSWORD}
 }
}
Database instance
val dbConfig: DatabaseConfig[JdbcProfile] = DatabaseConfig.forConfig("sqlserver")
val db: JdbcProfile#Backend#Database = dbConfig.db

SBT project setup

For the example used in this blog post following dependencies and versions of respective artifacts are used
  1. Scala 2.11.11
  2. SBT 0.13.17
  3. Slick 3.2.3
  4. HikariCP 3.2.3
  5. Mssql JDBC 6.2.1.jre8
which inside our build.sbt file will look like the following set of instructions
name := "mssql-example"

version := "1.0"

scalaVersion := "2.11.11"

libraryDependencies ++= Seq(
 "com.typesafe.slick" %% "slick" % "3.2.3",
 "com.typesafe.slick" %% "slick-hikaricp" % "3.2.3",
 "com.microsoft.sqlserver" % "mssql-jdbc" % "6.2.1.jre8"
)
and the instructions of build.properties file will be
sbt.version = 0.13.17
The settings required to configure Microsoft SQL Server should go inside application.conffile, whose instructions would be to specify the details of our database

sqlserver = {
 driver = "slick.jdbc.SQLServerProfile$"
 db {
  host = ${?SQLSERVER_HOST}
  port = ${?SQLSERVER_PORT}
  databaseName = ${?SQLSERVER_DB_NAME}

  url = "jdbc:sqlserver://"${sqlserver.db.host}":"${sqlserver.db.port}";databaseName="${sqlserver.db.databaseName}
  user = ${?SQLSERVER_USERNAME}
  password = ${?SQLSERVER_PASSWORD}
 }
}
where it can be seen that SQLSERVER_HOST, SQLSERVER_PORT, SQLSERVER_DB_NAME, SQLSERVER_USERNAME and SQLSERVER_PASSWORD are to be provided as environment variables.
Now moving onto our FRM (Functional Relational Mapping) and repository setup, the following import will be used for MS SQL Server Slick driver’s API
import slick.jdbc.SQLServerProfile.api._
And thereafter the FRM will look same as the rest of the FRM’s delineated on the official Slick documentation. For the example on this blog let’s use the following table structure
CREATE TABLE user_profiles (
 id         INT IDENTITY (1, 1) PRIMARY KEY,
 first_name VARCHAR(100) NOT NULL,
 last_name  VARCHAR(100) NOT NULL
)
whose functional relational mapping will look like this:
class UserProfiles(tag: Tag) extends Table[UserProfile](tag, "user_profiles") {

 def id: Rep[Int] = column[Int]("id", O.PrimaryKey, O.AutoInc)

 def firstName: Rep[String] = column[String]("first_name")

 def lastName: Rep[String] = column[String]("last_name")

 def * : ProvenShape[UserProfile] = (id, firstName, lastName) <>(UserProfile.tupled, UserProfile.unapply) // scalastyle:ignore

}
Moving further up with the CRUD operations, they are fairly straightforward as per the integrated query model provided by Slick, which can be seen from the following UserProfileRepository class
class UserProfileRepository {

 val userProfileQuery: TableQuery[UserProfiles] = TableQuery[UserProfiles]

 def insert(user: UserProfile): Future[Int] =
  db.run(userProfileQuery += user)

 def get(id: Int): Future[Option[UserProfile]] =
  db.run(
   userProfileQuery
    .filter(_.id === id)
    .take(1)
    .result
    .headOption)

 def update(id: Int, firstName: String): Future[Int] =
  db.run(
   userProfileQuery
    .filter(_.id === id)
    .map(_.firstName)
    .update(firstName))

 def delete(id: Int): Future[Int] =
  db.run(userProfileQuery.filter(_.id === id).delete)
Lastly, in order to get the database instance using the configurations provided in application.conf file, the following code snippet can be used
val dbConfig: DatabaseConfig[JdbcProfile] = DatabaseConfig.forConfig("sqlserver")
val db: JdbcProfile#Backend#Database = dbConfig.db
Working codebase of this example is available at the following repository: scala-slick-mssql.
Also, if you’re interested in knowing how data can be directly streamed from PostgreSQL to a client using Akka Stream and Scala Slick then you might find the following article useful: Streaming data from PostgreSQL using Akka Streams and Slick in Play Framework
This blog post has been inspired by an endeavor to make Microsoft SQL Server work with Slick and an answer on StackOverFlow which is the reference of the configurations.
Hope this helps :)
This article was first published on the Knoldus blog.

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