SQLDelight in Android: Getting Started

Aug 3 2021 · Kotlin 1.4, Android 11, Android Studio 4.1

Part 1: Preparation & Setup

05. Understand SQLDelight's Type System

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Previous episode: 04. Instantiate the Database Next episode: 06. Add Functions to Tables

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Let’s take a closer look at the Kotlin code that SQLDelight generated from the script files we have created previously.

CREATE TABLE bugAttributes (
  attributesId INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
  bugId INTEGER NOT NULL,
  size TEXT NOT NULL,
  weight TEXT NOT NULL,
- attack INTEGER NOT NULL,
- defense INTEGER NOT NULL,
+ attack INTEGER AS Int NOT NULL,
+ defense INTEGER AS Int NOT NULL,

  FOREIGN KEY(bugId)
    REFERENCES bug(bugId)
    ON DELETE CASCADE
);

CREATE TABLE inCollection (
  collectionId INTEGER NOT NULL,
  bugId INTEGER NOT NULL,
- quantity INTEGER NOT NULL,
+ quantity INTEGER AS Int NOT NULL,

  FOREIGN KEY(collectionId)
    REFERENCES collection(collectionId)
    ON DELETE CASCADE,

  FOREIGN KEY(bugId)
    REFERENCES bug(bugId)
    ON DELETE CASCADE
);

+import java.time.ZonedDateTime;

CREATE TABLE collection (
  collectionId INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
-  creationTime INTEGER NOT NULL,
+  creationTime INTEGER AS ZonedDateTime NOT NULL,
  name TEXT NOT NULL
);

class DatabaseRepository(driver: SqlDriver) {

-    private val database = Database(driver)
+    private val database = Database(
+        driver = driver,
+        collectionAdapter = 
+    )
}

class DatabaseRepository(driver: SqlDriver) {

    private val database = Database(
        driver = driver,
+        collectionAdapter = Collection.Adapter(
+            creationTimeAdapter = 
+        )
    )
}

private val zonedDateTimeAdapter = object : ColumnAdapter<ZonedDateTime, Long> {
}

private val zonedDateTimeAdapter = object : ColumnAdapter<ZonedDateTime, Long> {
    override fun decode(databaseValue: Long): ZonedDateTime {
        TODO()
    }

    override fun encode(value: ZonedDateTime): Long {
        TODO()
    }
}

+private val UTC = ZoneId.of("UTC")

private val zonedDateTimeAdapter = object : ColumnAdapter<ZonedDateTime, Long> {
    override fun decode(databaseValue: Long): ZonedDateTime {
+        return ZonedDateTime.ofInstant(Instant.ofEpochSecond(databaseValue), UTC)
    }

    override fun encode(value: ZonedDateTime): Long {
        TODO()
    }
}

private val UTC = ZoneId.of("UTC")

private val zonedDateTimeAdapter = object : ColumnAdapter<ZonedDateTime, Long> {
    override fun decode(databaseValue: Long): ZonedDateTime {
        return ZonedDateTime.ofInstant(Instant.ofEpochSecond(databaseValue), UTC)
    }

    override fun encode(value: ZonedDateTime): Long {
+        return value.toEpochSecond()
    }
}

class DatabaseRepository(driver: SqlDriver) {

    private val database = Database(
        driver = driver,
        collectionAdapter = Collection.Adapter(
+            creationTimeAdapter = zonedDateTimeAdapter
        )
    )
}

-holder.creationTextView.text = item.creationTime.toString()
+holder.creationTextView.text = item.creationTime.format(formatter)