Slick – The modern Way to query your Data!

on

Jogja Digital Valley

Jochen Hülß

01/10/2014

The answer to life, the universe and everything?

13. April 2023 2

Bio of Jochen

• M.Sc. in Business Information Systems (Mannheim University)• Data Mining & Web Usage Mining• Cloud Technologies

• 5 years with SAP (Business Software Vendor)• Business Intelligence• Android Development

• Heinz-Nixdorf Fellowship-Program• Venture Capital Investment• Ideabox / Mountain SEA Ventures

Slick – TechTalk #42

13. April 2023 3

Before and after

Prerequisites

• Know about SQL• MVC Pattern• Collections in

programming• Ask directly!

Learning Goals

• Explain, what Slick is used for.• Know about the

advantages of Slick.• Know the basic

commands used for querying in Slick.

Slick – TechTalk #42

13. April 2023 4

MotivationWhat is Slick all about?

13. April 2023 5

Imagine a simple Database schema…

Slick – TechTalk #42

COFFEE

BUYER SALES

SUPPLIER

COF_ID(FK)

SUP_ID(FK)

PRICE AMOUNT

ID NAME

ID NAME COUNTRY

ID NAME COUNTRY FAV_COFFE_ID(FK)

13. April 2023 6

… being used for a Web Application

Slick – TechTalk #42

Web Framework

Database

Browser

HTML5 JavaScript CSS

JSON

SQL

View Controller Model

How can we simplify the Database-Controller

connection?

13. April 2023 8

As a developer, I want to use Slick!

Modern database query & access library for Scala

Slick – TechTalk #42

Scala Runtime

PostgreSQL Database

SQL

Scala-Controller Slick-Model

13. April 2023 9

Features of Slick

• Easy• Database access just like Scala collections• Manages your Database sessions via JDBC• Supports plain SQL• Simple setup, many supported databases

• Precise• Compile time safety• Query re-use with ease Scala functions• Immutable collections• Stateless

Slick – TechTalk #42

Slick makes DB access scalable!

13. April 2023 10

Under the HoodHow does it work?

13. April 2023 11

Slick‘s Lifted Query Processing

Slick – TechTalk #42

Every DB table gets its own type classes

lifting

Generate syntax tree for SQL query

computation

13. April 2023 12

Example Code for Relation Coffee

1) /** Entity class storing rows of table Coffee */

2) case class CoffeeRow(id: Long, name: Option[String])

3) /** Table description of table coffee. Objects of this class serve as prototypes for rows in queries. */

4) class Coffee(tag: Tag) extends Table[CoffeeRow](tag, "coffee") {

5) def * = (id, name) <> (CoffeeRow.tupled, CoffeeRow.unapply)

6) val id: Column[Long] = column[Long]("id", O.AutoInc, O.PrimaryKey)

7) val name: Column[Option[String]] = column[Option[String]]("name")

8) }

9) /** Collection-like TableQuery object for table Coffee */

10) lazy val Coffee = new TableQuery(tag => new Coffee(tag))

Slick – TechTalk #42

13. April 2023 13

Setup

• Scala >2.10

• Scala Build Tool >0.13

• Add dependencies• Slick >2.0• Database specific driver

• Import database driver

Many tutorials available

Slick – TechTalk #42

More Info:http://

slick.typesafe.com/doc/2.0.1/

gettingstarted.html

13. April 2023 14

Getting startedSchema Generation, Connection, Data inserts

13. April 2023 15

Our sample Database schema

Slick – TechTalk #42

COFFEE

BUYER SALES

SUPPLIER

COF_ID(FK)

SUP_ID(FK)

PRICE AMOUNT

ID NAME

ID NAME COUNTY

ID NAME COUNTRY FAV_COFFE_ID(FK)

13. April 2023 16

Getting started

Task

1. Schema Generation

2. Connection

3. Data inserts

Tips and Tricks

• Use Slick‘s SourceCodeGenerator

• Use wrapped connection object

• Single or batch (faster) insert possible• ID return only with single

Slick – TechTalk #42

13. April 2023 17

Basic QueriesProjection, Filtering, Sorting

13. April 2023 18

Basic Queries

Task

1. Projection1. Result list()2. Result foreach()3. Result first()

2. Where3. Where with LIKE4. Where with AND / OR5. Sorting

Tips and Tricks

• “map()” iterates over collection

• Result with “list()” in memory, with “foreach()” only temporary

• If attribute is not “NOT NULL” on database use “Option()”

• Filter with “===“

• Use “toLowerCase()” with “like()”

Slick – TechTalk #42

13. April 2023 19

Advanced QueriesJoins, Aggregates, nested Queries

13. April 2023 20

Advanced Queries

Task

1. Inner Join2. Inner Join with condition3. Inner Join with foreign

key4. Inner Join with 3 tables5. Aggregation and nested

queries (I)6. Aggregation and nested

queries (II)

Tips and Tricks

• For-Loop connects two collections

• Where conditions start with “if“

• Slick model provides helper for foreign key relations

• “groupBy” new collection with tuples

• Aggregation max, min, sum, …

• Use queries within other queries

Slick – TechTalk #42

13. April 2023 21

ConclusionIs Slick the answer to life, the universe and everything?!

13. April 2023 22Slick – TechTalk #42

Thoughts on Slick

- Generated Queries

(readability)

+ Usability in Scala

+ Production ready

+ Level of control

+ Lightweight

13. April 2023 23

References

• http://slick.typesafe.com/doc/2.0.1/

• https://mackler.org/LearningSlick2/

• “Slick - The Structured Way” from SlideShare

• “Brief introduction of Slick” from SlideShare

Slick – TechTalk #42

Thank you!Jogja Digital ValleyJochen Hülß (jochen@huelss.de)01/10/2014