Use Supabase with Android Kotlin

1. Create a Supabase project#

Before you can use Supabase, you need a Supabase project. You can create a project visually in the Dashboard or programmatically using the Management API.

2. Set up your database#

When your Supabase project is up and running, create an instruments table with some sample data.

Then set a secure baseline by setting only the privileges each Postgres role needs, add Row Level Security (RLS) for enhanced security for database data by default, and create an RLS policy to make the data in your table publicly readable.

You can click this button to prefill all the SQL needed in the SQL editor of your project in the Dashboard.

3. Create an Android app with Android Studio#

Select the Android Studio > New > New Android Project menu item.

4. Install dependencies#

Open build.gradle.kts (app) file and add the serialization plugin, Ktor client, and Supabase client.

Replace the version placeholders $kotlin_version with the Kotlin version of the project, and $supabase_version and $ktor_version with the respective latest versions.

1
plugins {
2
  ...
3
  kotlin("plugin.serialization") version "$kotlin_version"
4
}
5
...
6
dependencies {
7
  ...
8
  implementation(platform("io.github.jan-tennert.supabase:bom:$supabase_version"))
9
  implementation("io.github.jan-tennert.supabase:postgrest-kt")
10
  implementation("io.ktor:ktor-client-android:$ktor_version")
11
}

5. Add internet access permission#

Add the following line to the AndroidManifest.xml file under the manifest tag and outside the application tag.

1
...
2
<uses-permission android:name="android.permission.INTERNET" />
3
...

Get API details#

To interact with data in database tables, you use the client libraries that wrap the auto-generated Data API endpoints, authenticating using the Project URL and key from the project Connect dialog.

6. Initialize the Supabase client#

You can create a Supabase client whenever you need to perform an API call.

For a quick example, create a client at the top of the MainActivity.kt file below the imports.

Replace the supabaseUrl and supabaseKey with your own, which you can get from the helper above, or from the project Connect panel:

1
import ...
2
3
val supabase = createSupabaseClient(
4
    supabaseUrl = "https://xyzcompany.supabase.co",
5
    supabaseKey = "your_publishable_key"
6
  ) {
7
    install(Postgrest)
8
}
9
...

7. Create a data model for instruments#

Create a serializable data class to represent the data from the database.

Add the following below the createSupabaseClient function in the MainActivity.kt file.

1
@Serializable
2
data class Instrument(
3
    val id: Int,
4
    val name: String,
5
)

8. Query data from the app#

Use LaunchedEffect to fetch data from the database and display it in a LazyColumn.

Replace the default MainActivity class with the following code.

1
class MainActivity : ComponentActivity() {
2
    override fun onCreate(savedInstanceState: Bundle?) {
3
        super.onCreate(savedInstanceState)
4
        setContent {
5
            SupabaseTutorialTheme {
6
                // A surface container using the 'background' color from the theme
7
                Surface(
8
                    modifier = Modifier.fillMaxSize(),
9
                    color = MaterialTheme.colorScheme.background
10
                ) {
11
                    InstrumentsList()
12
                }
13
            }
14
        }
15
    }
16
}
17
18
@Composable
19
fun InstrumentsList() {
20
    var instruments by remember { mutableStateOf<List<Instrument>>(listOf()) }
21
    LaunchedEffect(Unit) {
22
        withContext(Dispatchers.IO) {
23
            instruments = supabase.from("instruments")
24
                              .select().decodeList<Instrument>()
25
        }
26
    }
27
    LazyColumn {
28
        items(
29
            instruments,
30
            key = { instrument -> instrument.id },
31
        ) { instrument ->
32
            Text(
33
                instrument.name,
34
                modifier = Modifier.padding(8.dp),
35
            )
36
        }
37
    }
38
}

9. Start the app#

Run the app on an emulator or a physical device by clicking the Run app button in Android Studio.