Introduction to Apollo Kotlin

📣 Apollo Kotlin 3 is generally available. If you're using Apollo Android 2.x, see the migration guide. You can also view the 2.x docs.

Apollo Kotlin (formerly Apollo Android) is a GraphQL client that generates Kotlin and Java models from GraphQL queries.

Apollo Kotlin executes queries and mutations against a GraphQL server and returns results as query-specific Kotlin types. This means you don't have to deal with parsing JSON, or passing around Maps and making clients cast values to the right type manually. You also don't have to write model types yourself, because these are generated from the GraphQL definitions your UI uses.

Because generated types are query-specific, you can only access data that you actually specify as part of a query. If you don't ask for a particular field in a query, you can't access the corresponding property on the returned data structure.

This library is designed primarily with Android in mind, but you can use it in any Java/Kotlin app, including multiplatform.

Features

• Java and Kotlin Multiplatform code generation

• Queries, Mutations and Subscriptions

• Reflection-free parsing

• Normalized cache

• Custom scalar types

• HTTP cache

• Auto Persisted Queries

• Query batching

• File uploads

• Espresso IdlingResource

• Fake models for tests

• AppSync and graphql-ws websockets

• GraphQL AST parser

Multiplatform

Apollo Kotlin is a Kotlin Multiplatform project.

Here's the current matrix of supported features per platform:

¹: Apple currently includes:

• macosX64

• macosArm64

• iosArm64

• iosX64

• iosSimulatorArm64

• watchosArm32

• watchosArm64

• watchosSimulatorArm64

• tvosArm64

• tvosX64

• tvosSimulatorArm64

Getting started

If you are new to GraphQL, check out the tutorial that will guide you through building an Android app using Apollo, Kotlin and coroutines.

If you'd like to add Apollo Kotlin to an existing project, follow these steps:

Add the plugin to your build.gradle.kts:

1plugins {
2  id("com.apollographql.apollo3").version("3.8.3")
3}

Add the runtime dependency:

1dependencies {
2  implementation("com.apollographql.apollo3:apollo-runtime:3.8.5")
3}

Set the package name to use for the generated models:

1apollo {
2  service("service") {
3    packageName.set("com.example")
4  }
5}

Apollo Kotlin supports three types of files:

• .graphqls schema files: describes the types in your backend using the GraphQL syntax.

• .json schema files: describes the types in your backend using the Json syntax.

• .graphql executable files: describes your queries and operations in the GraphQL syntax.

By default, Apollo Kotlin requires a schema in your module's src/main/graphql directory. You can download a schema using introspection with the ./gradlew downloadApolloSchema task. Sometimes introspection is disabled and you will have to ask your backend team to provide a schema. Copy this schema to your module:

1cp ${schema} ${module}/src/main/graphql/

Write a query in a ${module}/src/main/graphql/GetRepository.graphql file:

1query HeroQuery($id: String!) {
2  hero(id: $id) {
3    id
4    name
5    appearsIn
6  }
7}

Build your project. This will generate a HeroQuery class that you can use with an instance of ApolloClient:

1  // Create a client
2  val apolloClient = ApolloClient.Builder()
3      .serverUrl("https://example.com/graphql")
4      .build()
5
6  // Execute your query. This will suspend until the response is received.
7  val response = apolloClient.query(HeroQuery(id = "1")).execute()
8
9  println("Hero.name=${response.data?.hero?.name}")

To learn more about other Apollo Kotlin APIs:

• Execute your first mutation

• Handle custom scalar types

• Factor common patterns using fragments

Requirements

Some platforms have specific requirements:

• Android API level 21+ (apollo-http-cache and apollo-adapters require enabling core library desugaring on Android API levels < 26)

• JDK 8+ (JDK 11+ when using Android Gradle Plugin 7.0+)

• iOS 13+

For building, it requires:

• Gradle 5.6

• Kotlin 1.8+ for JVM projects

• Kotlin 1.9+ for native projects

Proguard / R8 configuration

As the code generated by Apollo Kotlin doesn't use any reflection, it can safely be optimized / obfuscated by Proguard or R8, so no particular exclusions need to be configured.

IntelliJ Plugin

The JS Graphql IntelliJ Plugin provides auto-completion, error highlighting, and go-to-definition functionality for your .graphql files. You can create a .graphqlconfig file to use GraphQL scratch files to work with your schema outside product code (such as to write temporary queries to test resolvers). Make sure you check "Apollo Kotlin" in the plugin's settings, so directives such as @nonnull and typePolicy are recognized.

Releases

The latest version is

Check the changelog for the release history.

Releases are hosted on Maven Central. The plugin is additionally hosted on the Gradle Plugin Portal

1plugins {
2  id("com.apollographql.apollo3").version("3.8.3")
3}
4
5repositories {
6  mavenCentral()
7}
8
9dependencies {
10  implementation("com.apollographql.apollo3:apollo-runtime:3.8.5")
11
12  // optional: if you want to use the normalized cache
13  implementation("com.apollographql.apollo3:apollo-normalized-cache-sqlite:3.8.5")
14  // optional: if you just want the generated models and parsers and write your own HTTP code/cache code, you can remove apollo-runtime
15  // and use apollo-api instead
16  implementation("com.apollographql.apollo3:apollo-api:3.8.5")
17}

Snapshots

Latest development changes are available in Sonatype's snapshots repository:

1// build.gradle.kts
2repositories {
3  maven {
4    url = uri("https://s01.oss.sonatype.org/content/repositories/snapshots/")
5  }
6  mavenCentral()
7  // other repositories...
8}
9
10// settings.gradle.kts
11pluginManagement {
12  repositories {
13    maven {
14      url = uri("https://s01.oss.sonatype.org/content/repositories/snapshots/")
15    }
16    gradlePluginPortal()
17    mavenCentral()
18    // other repositories...
19  }
20}

And then use the 3.8.6-SNAPSHOT version for the plugin and libraries.

Contributing

If you'd like to contribute, please see Contributing.md.

Community integrations

• If you're using the Maven build tool, https://github.com/aoudiamoncef/apollo-client-maven-plugin is a Maven plugin that calls the Apollo Android compiler to generate your Java/Kotlin sources.

• If you're using Absinthe Phoenix subscriptions, kotlin-phoenix has a PhoenixNetworkTransport that you can use together with ApolloClient (doc)

Additional resources

• A journey to Kotlin multiplatform: how the project was moved to Kotlin multiplatform, talk given at Kotliners in June 2020.

• #125, Fragmented Podcast: Why's and How's about Apollo Kotlin and the entire journey.

• GraphQL.org for an introduction and reference to GraphQL itself.

• apollographql.com to learn about Apollo open-source and commercial tools.

• The Apollo blog for long-form articles about GraphQL, feature announcements for Apollo, and guest articles from the community.

• The Apollo Twitter account for in-the-moment news.