My presentation held at flatMap(Oslo)

1. ScalaQuery
flatMap(Oslo)
Trond Marius Øvstetun
© Mesan AS

2. Trond Marius Øvstetun
• Sjefskonsulentog
fagleder i Mesan
• Lidenskapelig
utvikler, arkitekt,
teamleder ++
• Java, Scala, HTML/js
• Alltid
på jakt etter
bedre, enklere
måter
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3. Data
• Vi har behov for å lagre data
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4. Data
• Vi har behov for å lagre data
• Ikke
alle bruker eller kan bruke
NoSQL
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5. Data
• Vi har behov for å lagre data
• Ikke
alle bruker eller kan bruke
NoSQL
• konservativ it-avdeling?
• legacy – eksisterende data
• andre behov?
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6. Data
• Vi har behov for å lagre data
• Ikke
alle bruker eller kan bruke
NoSQL
• konservativ it-avdeling?
• legacy – eksisterende data
• andre behov?
• av og til er relasjonsmodellen riktig
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7. SQL
• Hvordan jobber vi med RDBMS på
best mulig måte?
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8. SQL
• Hvordan jobber vi med RDBMS på
best mulig måte?
• JDBC?
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9. SQL
• Hvordan jobber vi med RDBMS på
best mulig måte?
• JDBC?
• ORM?
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10. SQL
• Hvordan jobber vi med RDBMS på
best mulig måte?
• JDBC?
• ORM?
• Hibernate?
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11. SQL
• Hvordan jobber vi med RDBMS på
best mulig måte?
• JDBC?
• ORM?
• Hibernate?
• Anorm? Mapper? Record?
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12. ScalaQuery
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13. ScalaQuery
A type-safe database API for
Scala
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14. ScalaQuery
A type-safe database API for
Scala
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15. En enkel domenemodell
«enumeration»
Artist
Genre
Album
name : String
Rock 1
biography : Text name : String
Pop *
Classic mainGenre : Genre release : Date
Blues founded : Date rating : Option[Int]
Rap split : Option[Date]
1
HipHop
Alternative *
*
* Song
name : String
Person duration : Int
firstname : String trackNumber : Int
lastname : String
biography : Text
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16. Koble til en database
• Med javax.sql.DataSource
def myDs : DataSource = {...}
val db = Database.forDataSource(myDs)
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17. Koble til en database
• Alternativt
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18. Koble til en database
• Alternativt
Database.forName("jdbc/my_ds") //JNDI
Database.forURL("jdbc:h2:test")
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19. Gjøre noe med databasen
val db = {...}
db withSession {
do_something()
}
import Database.threadLocalSession
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20. StaticQuery
Håndkodet SQL mot databasen
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21. Spørringer
val q = StaticQuery[Int] +
"select count(id) from Artists"
val count = q.first()
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22. Spørringer
val q = StaticQuery[Int, (Int, String)] +
"select id, name from Artists where id = ?"
val (id,name) = q(1001).first
val artist : (Int, String) = q(1001).first
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23. Mapping av resultat
case class Artist(id:Int, name:String)
val q = StaticQuery.query[Int, (Int, String)](
"select id, name from Artists where id = ?")
val qMapped = q.mapResult[Artist]({
case (a, b) => Artist(a, b)
})
var a:Artist = qMapped(1001).first()
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24. Implisitt mapping av
case class Artist(id:Int, name:String)
implicit val artMapper = GetResult(
(r: PositionedResult) => new Artist(r<<, r<<))
val q = StaticQuery.query[Int, Art](
"select id, name from Artists where id = ?")
val a:Artist = q(1001).first
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25. Insert / Update
import org.scalaquery.simple.StaticQuery._
val q = query[(String, String), Int](
"insert into Artists(name, biography) "+
"values (?, ?)")
val q2 = q("Seigmen", "")
q2.execute()
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26. ScalaQuery
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27. ScalaQuery
På tide å få noe igjen?
Hva om ...
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28. En enkel domenemodell
«enumeration»
Artist
Genre
Album
name : String
Rock 1
biography : Text name : String
Pop *
Classic mainGenre : Genre release : Date
Blues founded : Date rating : Option[Int]
Rap split : Option[Date]
1
HipHop
Alternative *
*
* Song
name : String
Person duration : Int
firstname : String trackNumber : Int
lastname : String
biography : Text
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29. Mapping til en tabell
object Artists extends Table[
(Int, String, String,
Genre.Genre, Date, Option[Date])
]("ARTISTS") {
...
}
Artist
name : String
biography : Text
mainGenre : Genre
founded : Date
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split : Option[Date]

30. Mapping til en tabell
object Artists extends Table (...) {
def id = column[Int]("ID", O PrimaryKey)
def name = column[String]("NAME")
def biography = column[String]("BIOGRAPHY")
def maingenre = column[Genre.Genre]("MAINGENRE")
def founded = column[Date]("FOUNDED")
def split = column[Option[Date]]("SPLIT")
} Artist
name : String
biography : Text
mainGenre : Genre
founded : Date
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split : Option[Date]

31. Mapping til en tabell
object Artists extends Table (...) {
...
def * = id ~ name ~ biography ~
maingenre ~ founded ~ split
def i = name ~ biography ~
maingenre ~ founded ~ split
}
Artist
name : String
biography : Text
mainGenre : Genre
founded : Date
© Mesan AS
split : Option[Date]

32. Mapping med case-klasse
case class Artist(
id:Int,name:String, bio:String,
mainGenre:Genre.Genre, founded:Date,
split:Option[Date])
object Artists extends Table[Artist]("ARTISTS") {
def * = id ~ .. ~ split <> (Artist, Artist.unapply _)
} Artist
name : String
biography : Text
mainGenre : Genre
founded : Date
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split : Option[Date]

33. Bruke egne typer
column[Genre.Genre]("MAINGENRE")
object Genre extends Enumeration {
type Genre = Value «enumeration»
Genre
val Rock = Value(1) Rock
Pop
Classic
...
Blues
Rap
HipHop
Alternative
val Alternative = Value(7)
}
implicit val genreMapper =
MappedTypeMapper.base[Genre.Genre, Int](
_.id, Genre(_))
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34. Bruke egne typer
column[Duration]("DURATION")
case class Duration(mins:Int, secs:Int)
implicit object durationMapper extends
MappedTypeMapper[Duration, Int]
with BaseTypeMapper[Duration]
with NumericTypeMapper {
def map(dur: Duration) =
dur.mins * 60 + dur.secs
def comap(secs: Int) =
Duration(secs / 60, secs % 60)
} © Mesan AS

35. Inserts
val i: Int = Artists.i.insert(
("Seigmen", "", Genre.Rock,
date("1989-12-27"),
Some(date("2008-06-22"))))
// i is number of rows affected
val artists : List[(...)] = ...
val i = Artists.i.insertAll(artists :_*)
// i is Option[Int] - num affected
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36. Enkle spørringer
def findArtist(id:Int) : Option[(...)] = {
val q = Artists.createFinderBy(_.id)
q(id).firstOption
}
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37. Enkle spørringer
def findArtist(id:Int) : Option[(...)] = {
val q = Artists.createFinderBy(_.id)
q(id).firstOption
}
def highRatedAlbums : List[...] = {
val q = Albums.filter(_.rating === (Six:Rating))
q.list
}
def unRatedAlbums : List[...] = {
val q = Albums.filter(_.rating isNull)
q.list
} © Mesan AS

38. Bruk av spørringer
val resList = q.list
val resOption = q.firstOption
val res = q.first
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39. Mer generelle spørringer
val q1 =
Artists.filter(_.maingenre === Genre.Rock)
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40. Mer generelle spørringer
val q1 =
Artists.filter(_.maingenre === Genre.Rock)
val q = for {
a <- Artists if a.maingenre === Genre.Rock
} yield a
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41. Generell spørring
val aQuery = for {
x1 <- generator
x2 <- generator
...
xN <- generator
guard
} yield projection
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42. Parametrisert
val qArtist = for {
n <- Parameters[String]
a <- Artists if a.name === n
} yield a.id ~ a.name
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43. Parametrisert
val qArtist = for {
n <- Parameters[String]
a <- Artists if a.name === n
} yield a.id ~ a.name
val qTool = qArtist("Tool")
val (id, name) = qTool.first
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44. Spørringer
• Er lazy
• Er immutable
• Dele og gjenbruke
• Byggeklosser
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45. Spørringer
• Er lazy
• Er immutable
• Dele og gjenbruke
• Byggeklosser
val q1 = for (a <- Artists) yield a
val q2 = for (a <- q1) yield a.id ~ a.name
val q3 = q2.take(10).drop(50)
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46. Update
val q = for {
a <- Artists if a.id === 1001
} yield a.name
q.update("updated") // num affected
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47. Delete
val q = for {
a <- Albums if a.id === 1001
} yield a
q.delete
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48. Relasjoner /
object Albums extends Table[(...)]("ALBUMS") {
def artist_id = column[Int]("ARTIST_ID")
def artist =
foreignKey("albums_artists_fk", artist_id, Artists)(_.id)
def * = id ~ name ~ release ~ rating ~ artist_id
}
Artist
Album
name : String
1
biography : Text name : String
*
mainGenre : Genre release : Date
founded : Date rating : Option[Int]
split : Option[Date]
© Mesan AS

49. Joins
Artist
val q = for { Album
name : String
1
biography : Text name : String
*
mainGenre : Genre release : Date
al <- Albums founded : Date
split : Option[Date]
rating : Option[Int]
a <- Artists
if al.artist_id === a.id
} yield a.name ~ al.name
val q = for {
al <- Albums
a <- al.artist
} yield a.name ~ al.name
val q = for {
(al, a) <- Albums innerJoin Artists on (_.artist_id is _.id)
} yield a.name ~ al.name
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50. Veien videre?
ScalaQuery => SLICK
Scala Language Integrated
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51. SLICK
• Generiskrammeverk for
spørringer mot data
• Ulike backends
• SQL,
NoSQL, json, WebServices,
XML ...
• Nærmere “vanlig” Scala-kode,
backend som scala Collection
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52. Q&A
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53. Q&A
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54. takk for meg
tmo@mesan.no
@ovstetun
github.com/ovstetun/scala-persistence
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