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Getting started on Kotlin Native with SQLDelight

First apply the gradle plugin in your project.

buildscript {
  repositories {
    google()
    mavenCentral()
  }
  dependencies {
    classpath 'com.squareup.sqldelight:gradle-plugin:1.5.3'
  }
}

apply plugin: 'com.squareup.sqldelight'

sqldelight {
  Database { // This will be the name of the generated database class.
    packageName = "com.example"
  }
}

Put your SQL statements in a .sq file under src/main/sqldelight. Typically the first statement in the SQL file creates a table.

-- src/main/sqldelight/com/example/sqldelight/hockey/data/Player.sq

CREATE TABLE hockeyPlayer (
  player_number INTEGER NOT NULL,
  full_name TEXT NOT NULL
);

CREATE INDEX hockeyPlayer_full_name ON hockeyPlayer(full_name);

INSERT INTO hockeyPlayer (player_number, full_name)
VALUES (15, 'Ryan Getzlaf');

From this SQLDelight will generate a Database Kotlin class with an associated Schema object that can be used to create your database and run your statements on it. Doing this also requires a driver, which SQLDelight provides implementations of:

kotlin {
  // or sourceSets.iosMain, sourceSets.windowsMain, etc.
  sourceSets.nativeMain.dependencies {
    implementation "com.squareup.sqldelight:native-driver:1.5.3"
  }
}
val driver: SqlDriver = NativeSqliteDriver(Database.Schema, "test.db")

SQL statements inside a .sq file can be labeled to have a typesafe function generated for them available at runtime.

selectAll:
SELECT *
FROM hockeyPlayer;

insert:
INSERT INTO hockeyPlayer(player_number, full_name)
VALUES (?, ?);

insertFullPlayerObject:
INSERT INTO hockeyPlayer(player_number, full_name)
VALUES ?;

Files with labeled statements in them will have a queries file generated from them that matches the .sq file name - putting the above sql into Player.sq generates PlayerQueries.kt. To get a reference to PlayerQueries you need to wrap the driver we made above:

// In reality the database and driver above should be created a single time
// and passed around using your favourite dependency injection/service
// locator/singleton pattern.
val database = Database(driver)

val playerQueries: PlayerQueries = database.playerQueries

println(playerQueries.selectAll().executeAsList())
// Prints [HockeyPlayer(15, "Ryan Getzlaf")]

playerQueries.insert(player_number = 10, full_name = "Corey Perry")
println(playerQueries.selectAll().executeAsList())
// Prints [HockeyPlayer(15, "Ryan Getzlaf"), HockeyPlayer(10, "Corey Perry")]

val player = HockeyPlayer(10, "Ronald McDonald")
playerQueries.insertFullPlayerObject(player)

And that's it! Check out the other pages on the sidebar for other functionality.

Reader Connection Pools

Disk databases can (optionally) have multiple reader connections. To configure the reader pool, pass the maxReaderConnections parameter to the various constructors of NativeSqliteDriver:

val driver: SqlDriver = NativeSqliteDriver(Database.Schema, "test.db", maxReaderConnections = 4)

Reader connections are only used to run queries outside of a transaction. Any write calls, and anything in a transaction, uses a singe connection dedicated to transactions.