# SmallRye GraphQL

This guide demonstrates how your Quarkus application can use SmallRye GraphQL, an implementation of the MicroProfile GraphQL specification.

As the GraphQL specification website states:

> GraphQL is a query language for APIs and a runtime for fulfilling those queries with your existing data. GraphQL provides a complete and understandable description of the data in your API, gives clients the power to ask for exactly what they need and nothing more, makes it easier to evolve APIs over time, and enables powerful developer tools.

GraphQL was originally developed by Facebook in 2012 and has been an open standard since 2015.

GraphQL is not a replacement for REST API specification but merely an alternative. Unlike REST, GraphQL API’s have the ability to benefit the client by:

Preventing Over-fetching and Under-fetching

  REST APIs are server-driven fixed data responses that cannot be determined by the client. Although the client does not require all the fields the client must retrieve all the data hence `Over-fetching`. A client may also require multiple REST API calls according to the first call (HATEOAS) to retrieve all the data that is required thereby `Under-fetching`.

API Evolution

  Since GraphQL API’s returns data that are requested by the client adding additional fields and capabilities to existing API will not create breaking changes to existing clients.

## Prerequisites

To complete this guide, you need:

- Roughly 15 minutes

- An IDE

- JDK 17+ installed with `JAVA_HOME` configured appropriately

- Apache Maven 3.9.9

- Optionally the Quarkus CLI if you want to use it

- Optionally Mandrel or GraalVM installed and configured appropriately if you want to build a native executable (or Docker if you use a native container build)

## Architecture

In this guide, we build a simple GraphQL application that exposes a GraphQL API at `/graphql`.

This example was inspired by a popular GraphQL API.

## Solution

We recommend that you follow the instructions in the next sections and create the application step by step. However, you can go right to the completed example.

Clone the Git repository: `git clone https://github.com/quarkusio/quarkus-quickstarts.git`, or download an archive.

The solution is located in the `microprofile-graphql-quickstart` directory.

## Creating the Maven Project

First, we need a new project. Create a new project with the following command:

CLI

    quarkus create app org.acme:microprofile-graphql-quickstart \
        --extension='quarkus-smallrye-graphql' \
        --no-code
    cd microprofile-graphql-quickstart

To create a Gradle project, add the `--gradle` or `--gradle-kotlin-dsl` option.

For more information about how to install and use the Quarkus CLI, see the Quarkus CLI guide.

Maven

    mvn io.quarkus.platform:quarkus-maven-plugin:3.20.2.1:create \
        -DprojectGroupId=org.acme \
        -DprojectArtifactId=microprofile-graphql-quickstart \
        -Dextensions='quarkus-smallrye-graphql' \
        -DnoCode
    cd microprofile-graphql-quickstart

To create a Gradle project, add the `-DbuildTool=gradle` or `-DbuildTool=gradle-kotlin-dsl` option.

For Windows users:

- If using cmd, (don’t use backward slash `\` and put everything on the same line)

- If using Powershell, wrap `-D` parameters in double quotes e.g. `"-DprojectArtifactId=microprofile-graphql-quickstart"`

This command generates a project, importing the `smallrye-graphql` extension.

If you already have your Quarkus project configured, you can add the `smallrye-graphql` extension to your project by running the following command in your project base directory:

CLI

    quarkus extension add quarkus-smallrye-graphql

Maven

    ./mvnw quarkus:add-extension -Dextensions='quarkus-smallrye-graphql'

Gradle

    ./gradlew addExtension --extensions='quarkus-smallrye-graphql'

This will add the following to your build file:

pom.xml

    <dependency>
        <groupId>io.quarkus</groupId>
        <artifactId>quarkus-smallrye-graphql</artifactId>
    </dependency>

build.gradle

    implementation("io.quarkus:quarkus-smallrye-graphql")

## Preparing an Application: GraphQL API

In this section we will start creating the GraphQL API.

First, create the following entities representing a film from a galaxy far, far away:

    package org.acme.microprofile.graphql;

    public class Film {

        public String title;
        public Integer episodeID;
        public String director;
        public LocalDate releaseDate;

    }

    public class Hero {

        public String name;
        public String surname;
        public Double height;
        public Integer mass;
        public Boolean darkSide;
        public LightSaber lightSaber;
        public List<Integer> episodeIds = new ArrayList<>();

    }

    enum LightSaber {
        RED, BLUE, GREEN
    }

| For readability we use classes with public fields, but classes with private fields with public getters and setters will also work.

The classes we have just created describe the GraphQL schema which is a set of possible data (objects, fields, relationships) that a client can access.

Let’s continue with an example CDI bean, that would work as a repository:

    @ApplicationScoped
    public class GalaxyService {

        private List<Hero> heroes = new ArrayList<>();

        private List<Film> films = new ArrayList<>();

        public GalaxyService() {

            Film aNewHope = new Film();
            aNewHope.title = "A New Hope";
            aNewHope.releaseDate = LocalDate.of(1977, Month.MAY, 25);
            aNewHope.episodeID = 4;
            aNewHope.director = "George Lucas";

            Film theEmpireStrikesBack = new Film();
            theEmpireStrikesBack.title = "The Empire Strikes Back";
            theEmpireStrikesBack.releaseDate = LocalDate.of(1980, Month.MAY, 21);
            theEmpireStrikesBack.episodeID = 5;
            theEmpireStrikesBack.director = "George Lucas";

            Film returnOfTheJedi = new Film();
            returnOfTheJedi.title = "Return Of The Jedi";
            returnOfTheJedi.releaseDate = LocalDate.of(1983, Month.MAY, 25);
            returnOfTheJedi.episodeID = 6;
            returnOfTheJedi.director = "George Lucas";

            films.add(aNewHope);
            films.add(theEmpireStrikesBack);
            films.add(returnOfTheJedi);

            Hero luke = new Hero();
            luke.name = "Luke";
            luke.surname = "Skywalker";
            luke.height = 1.7;
            luke.mass = 73;
            luke.lightSaber = LightSaber.GREEN;
            luke.darkSide = false;
            luke.episodeIds.addAll(Arrays.asList(4, 5, 6));

            Hero leia = new Hero();
            leia.name = "Leia";
            leia.surname = "Organa";
            leia.height = 1.5;
            leia.mass = 51;
            leia.darkSide = false;
            leia.episodeIds.addAll(Arrays.asList(4, 5, 6));

            Hero vader = new Hero();
            vader.name = "Darth";
            vader.surname = "Vader";
            vader.height = 1.9;
            vader.mass = 89;
            vader.darkSide = true;
            vader.lightSaber = LightSaber.RED;
            vader.episodeIds.addAll(Arrays.asList(4, 5, 6));

            heroes.add(luke);
            heroes.add(leia);
            heroes.add(vader);

        }

        public List<Film> getAllFilms() {
            return films;
        }

        public Film getFilm(int id) {
            return films.get(id);
        }

        public List<Hero> getHeroesByFilm(Film film) {
            return heroes.stream()
                    .filter(hero -> hero.episodeIds.contains(film.episodeID))
                    .collect(Collectors.toList());
        }

        public void addHero(Hero hero) {
            heroes.add(hero);
        }

        public Hero deleteHero(int id) {
            return heroes.remove(id);
        }

        public List<Hero> getHeroesBySurname(String surname) {
            return heroes.stream()
                    .filter(hero -> hero.surname.equals(surname))
                    .collect(Collectors.toList());
        }
    }

Now, let’s create our first GraphQL API.

Edit the `org.acme.microprofile.graphql.FilmResource` class as following:

    @GraphQLApi (1)
    public class FilmResource {

        @Inject
        GalaxyService service;

        @Query("allFilms") (2)
        @Description("Get all Films from a galaxy far far away") (3)
        public List<Film> getAllFilms() {
            return service.getAllFilms();
        }
    }

1 | `@GraphQLApi` annotation indicates that the CDI bean will be a GraphQL endpoint
2 | `@Query` annotation defines that this method will be queryable with the name `allFilms`
3 | Documentation of the queryable method

| The value of the `@Query` annotation is optional and would implicitly be defaulted to the method name if absent.

This way we have created our first queryable API which we will later expand.

## Launch

Launch the quarkus application in dev mode:

CLI

    quarkus dev

Maven

    ./mvnw quarkus:dev

Gradle

    ./gradlew --console=plain quarkusDev

## Introspect

The full schema of the GraphQL API can be retrieved by calling the following:

    curl http://localhost:8080/graphql/schema.graphql

The server will return the complete schema of the GraphQL API.

## GraphQL UI

| Experimental - not included in the MicroProfile specification

GraphQL UI is a great tool permitting easy interaction with your GraphQL APIs.

The Quarkus `smallrye-graphql` extension ships with GraphiQL and enables it by default in `dev` and `test` modes, but it can also be explicitly configured for `production` mode as well, by setting the `quarkus.smallrye-graphql.ui.always-include` configuration property to `true`.

The GraphQL UI can be accessed from http://localhost:8080/q/graphql-ui/ .

Have a look at the Authorization of Web Endpoints Guide on how to add/remove security for the GraphQL UI.

## Query the GraphQL API

Now visit the GraphQL UI page that has been deployed in `dev` mode.

Enter the following query to the GraphQL UI and press the `play` button:

    query allFilms {
      allFilms {
        title
        director
        releaseDate
        episodeID
      }
    }

Since our query contains all the fields in the `Film` class we will retrieve all the fields in our response. Since GraphQL API responses are client determined, the client can choose which fields it will require.

Let’s assume that our client only requires `title` and `releaseDate` making the previous call to the API `Over-fetching` of unnecessary data.

Enter the following query into the GraphQL UI and hit the `play` button:

    query allFilms {
      allFilms {
        title
        releaseDate
      }
    }

Notice in the response we have only retrieved the required fields. Therefore, we have prevented `Over-fetching`.

Let’s continue to expand our GraphQL API by adding the following to the `FilmResource` class.

        @Query
        @Description("Get a Films from a galaxy far far away")
        public Film getFilm(@Name("filmId") int id) {
            return service.getFilm(id);
        }

| Notice how we have excluded the value in the `@Query` annotation. Therefore, the name of the query is implicitly set as the method name excluding the `get`.

This query will allow the client to retrieve the film by id, and the `@Name` annotation on the parameter changes the parameter name to `filmId` rather than the default `id` that it would be if you omit the `@Name` annotation.

Enter the following into the `GraphQL UI` and make a request.

    query getFilm {
      film(filmId: 1) {
        title
        director
        releaseDate
        episodeID
      }
    }

The `film` query method requested fields can be determined as such in our previous example. This way we can retrieve individual film information.

However, say our client requires both films with filmId `0` and `1`. In a REST API the client would have to make two calls to the API. Therefore, the client would be `Under-fetching`.

In GraphQL, it is possible to make multiple queries at once.

Enter the following into the `GraphQL UI` to retrieve two films:

    query getFilms {
      film0: film(filmId: 0) {
        title
        director
        releaseDate
        episodeID
      }
      film1: film(filmId: 1) {
        title
        director
        releaseDate
        episodeID
      }
    }

This enabled the client to fetch the required data in a single request.

## Expanding the API

Until now, we have created a GraphQL API to retrieve film data. We now want to enable the clients to retrieve the `Hero` data of the `Film`.

Add the following to our `FilmResource` class:

        public List<Hero> heroes(@Source Film film) { (1)
            return service.getHeroesByFilm(film);
        }

1 | Enable `List<Hero>` data to be added to queries that respond with `Film`

By adding this method we have effectively changed the schema of the GraphQL API. Although the schema has changed the previous queries will still work. Since we only expanded the API to be able to retrieve the `Hero` data of the `Film`.

Enter the following into the `GraphQL UI` to retrieve the film and hero data.

    query getFilmHeroes {
      film(filmId: 1) {
        title
        director
        releaseDate
        episodeID
        heroes {
          name
          height
          mass
          darkSide
          lightSaber
        }
      }
    }

The response now includes the heroes of the film.

### Batching

When you are exposing a `Collection` return like our `getAllFilms`, you might want to use the batch form of the above, to more efficiently fetch the heroes:

        public List<List<Hero>> heroes(@Source List<Film> films) { (1)
            // Here fetch all hero lists
        }

1 | Here receive the films as a batch, allowing you to fetch the corresponding heroes.

### Non blocking

Queries can be made reactive by using `Uni` as a return type, or adding `@NonBlocking` to the method:

        @Query
        @Description("Get a Films from a galaxy far far away")
        public Uni<Film> getFilm(int filmId) {
            // ...
        }

Or you can use `@NonBlocking`:

        @Query
        @Description("Get a Films from a galaxy far far away")
        @NonBlocking
        public Film getFilm(int filmId) {
            // ...
        }

Using `Uni` or `@NonBlocking` means that the request will be executed on Event-loop threads rather than Worker threads.

You can mix Blocking and Non-blocking in one request,

        @Query
        @Description("Get a Films from a galaxy far far away")
        @NonBlocking
        public Film getFilm(int filmId) {
            // ...
        }

        public List<Hero> heroes(@Source Film film) {
            return service.getHeroesByFilm(film);
        }

Above will fetch the film on the event-loop threads, but switch to the worker thread to fetch the heroes.

## Abstract Types

The current schema is simple with only two concrete types, `Hero` and `Film`. Now we want to expand our API with additional types and add some abstractions that make interacting with them easy for clients.

### Interfaces

Let’s give our heroes some allies.

First, create a new entity to represent our `Ally`.

    public class Ally {

        public String name;
        public String surname;
        public Hero partner;
    }

Update the `GalaxyService` to have some allies.

        private List<Ally> allies = new ArrayList();

        public GalaxyService() {
            // ...

            Ally jarjar = new Ally();
            jarjar.name = "Jar Jar";
            jarjar.surname = "Binks";
            allies.add(jarjar);
        }

        public List<Ally> getAllAllies() {
            return allies;
        }

Let’s also update `FilmResource` to allow clients to query for all allies:

        @Query
        public List<Ally> allies() {
            return service.getAllAllies();
        }

Enter the following into the `GraphQL UI` and make a request.

    query getAllies {
        allies {
            name
            surname
        }
    }

Notice that `Ally` has a some of the same fields as a `Hero`. To better make queries easier for clients, let’s create an abstraction for any character.

Create a new Java interface that defines our common character traits.

    public interface Character {

        (1)
        String getName();
        String getSurname();
    }

1 | Getters defined in an interface will define the GraphQL fields that it contains

Now, update our `Hero` and `Ally` entities to implement this interface.

    public class Hero implements Character {
        // ...

        (1)
        public String getName() {
            return name;
        }

        (1)
        public String getSurname() {
            return surname;
        }
    }

    public class Ally implements Character {
        // ...

        (1)
        public String getName() {
            return name;
        }

        (1)
        public String getSurname() {
            return surname;
        }
    }

1 | Because interfaces can’t define fields, we have to implement the getters

By adding an interface and updating existing entities to implement it, we have effectively changed the schema. The updated schema will now include the new `Ally` type and `Character` interface.

    (1)
    interface Character {
        name: String
        surname: String
    }

    (2)
    type Ally implements Character {
        name: String
        surname: String
        partner: Hero
    }

    (3)
    type Hero implements Character {
        name: String
        surname: String
        # ...
    }

1 | The `Character` interface was defined with the getters as fields
2 | The `Ally` type was added and it implements `Character`
3 | The `Hero` type was updated to implement `Character`

Update our `GalaxyService` to provide all characters.

        public List<Character> getAllCharacters() {
            List<Character> characters = new ArrayList<>();
            characters.addAll(heroes);
            characters.addAll(allies);
            return characters;
        }

Now we can allow clients to query for all characters, not just heroes.

Add the following to our `FilmResource` class:

        @Query
        @Description("Get all characters from a galaxy far far away")
        public List<Character> characters() {
            return service.getAllCharacters();
        }

Enter the following into the `GraphQL UI` and make a request.

    query getCharacters {
        characters {
            name
            surname
        }
    }

### Unions

| Experimental - not included in the MicroProfile specification

So far, our API has only allowed us to query directly for an entity or list of entities. Now we want to allow clients to search all of our entities. While `Hero` and `Ally` have a shared abstract type of `Character`, there is no abstraction that also includes `Film`.

First, create this new abstract type representing the possible return types for a search result.

    package org.acme.microprofile.graphql;

    import io.smallrye.graphql.api.Union;

    @Union (1)
    public interface SearchResult {

    }

1 | `@Union` is required to indicate this Java interface represents a GraphQL union, not a GraphQL interface

| The Java interface representing the GraphQL union does not have to be empty, but any getters defined will not explicitly change the GraphQL schema.

Update our entities to implement `SearchResult`:

    public class Film implements SearchResult {
        // ...
    }

    public interface Character implements SearchResult {
        // ...
    }

    public class Hero implements Character {
        // ...
    }

    public class Ally implements Character {
        // ...
    }

Update `GalaxyService` to provide search:

        public List<SearchResult> search(String query) {
            List<SearchResult> results = new ArrayList<>();
            List<Film> matchingFilms = films.stream()
                .filter(film -> film.title.contains(query)
                    || film.director.contains(query))
                .collect(Collectors.toList());
            results.addAll(matchingFilms);
            List<Character> matchingCharacters = getAllCharacters().stream()
                .filter(character -> character.getName().contains(query)
                    || character.getSurname().contains(query))
                .collect(Collectors.toList());
            results.addAll(matchingCharacters);
            return results;
        }

Add the following to our `FilmResource` class:

        @Query
        @Description("Search for heroes or films")
        public List<SearchResult> search(String query) {
            return service.search(query);
        }

Enter the following into the `GraphQL UI` and make a request.

    query searchTheGalaxy {
        search(query: "a") {
            ... on Film {
                title
                director
            }
            ... on Character {
                name
                surname
            }
        }
    }

| We are able to use the `Character` interface because the `SearchResult` union contains members that implement it.

## Mutations

Mutations are used when data is created, updated or deleted.

Let’s now add the ability to add and delete heroes to our GraphQL API.

Add the following to our `FilmResource` class:

        @Mutation
        public Hero createHero(Hero hero) {
            service.addHero(hero);
            return hero;
        }

        @Mutation
        public Hero deleteHero(int id) {
            return service.deleteHero(id);
        }

Enter the following into the `GraphQL UI` to insert a `Hero`:

    mutation addHero {
      createHero(hero: {
          name: "Han",
          surname: "Solo"
          height: 1.85
          mass: 80
          darkSide: false
          episodeIds: [4, 5, 6]
              }
      )
      {
        name
        surname
      }
    }

By using this mutation we have created a `Hero` entity in our service.

Notice how in the response we have retrieved the `name` and `surname` of the created Hero. This is because we selected to retrieve these fields in the response within the `{ }` in the mutation query. This can easily be a server side generated field that the client may require.

Let’s now try deleting an entry:

    mutation DeleteHero {
      deleteHero(id :3){
        name
        surname
      }
    }

Similar to the `createHero` mutation method we also retrieve the `name` and `surname` of the hero we have deleted which is defined in `{ }`.

## Subscriptions

Subscriptions allow you to subscribe to a query. It allows you to receive events and is using web sockets. See the GraphQL over WebSocket Protocol spec for more details.

Example: We want to know when new Heroes are being created:

        BroadcastProcessor<Hero> processor = BroadcastProcessor.create(); (1)

        @Mutation
        public Hero createHero(Hero hero) {
            service.addHero(hero);
            processor.onNext(hero); (2)
            return hero;
        }

        @Subscription
        public Multi<Hero> heroCreated(){
            return processor; (3)
        }

1 | The `Multi` processor that will broadcast any new `Hero`es
2 | When adding a new `Hero`, also broadcast it
3 | Make the stream available in the schema and as a WebSocket during runtime

Any client that now connect to the `/graphql` WebSocket connection will receive events on new Heroes being created:

    subscription ListenForNewHeroes {
      heroCreated {
        name
        surname
      }
    }

## Creating Queries by fields

Queries can also be done on individual fields. For example, let’s create a method to query heroes by their last name.

Add the following to our `FilmResource` class:

        @Query
        public List<Hero> getHeroesWithSurname(@DefaultValue("Skywalker") String surname) {
            return service.getHeroesBySurname(surname);
        }

By using the `@DefaultValue` annotation we have determined that the surname value will be `Skywalker` when the parameter is not provided.

Test the following queries with the `GraphQL UI`:

    query heroWithDefaultSurname {
      heroesWithSurname{
        name
        surname
        lightSaber
      }
    }
    query heroWithSurnames {
      heroesWithSurname(surname: "Vader") {
        name
        surname
        lightSaber
      }
    }

## Context

You can get information about the GraphQL request anywhere in your code, using this experimental, SmallRye specific feature:

    @Inject
    Context context;

or as a parameter in your method if you are in the `GraphQLApi` class, for instance:

        @Query
        @Description("Get a Films from a galaxy far far away")
        public Film getFilm(Context context, int filmId) {
            // ...
        }

The context object allows you to get:

- the original request (Query/Mutation)

- the arguments

- the path

- the selected fields

- any variables

This allows you to optimize the downstream queries to the datastore.

See the JavaDoc for more details.

### GraphQL-Java

This context object also allows you to fall down to the underlying graphql-java features by using the leaky abstraction:

    DataFetchingEnvironment dfe = context.unwrap(DataFetchingEnvironment.class);

You can also get access to the underlying `graphql-java` during schema generation, to add your own features directly:

    public GraphQLSchema.Builder addMyOwnEnum(@Observes GraphQLSchema.Builder builder) {

        // Here add your own features directly, example adding an Enum
        GraphQLEnumType myOwnEnum = GraphQLEnumType.newEnum()
                .name("SomeEnum")
                .description("Adding some enum type")
                .value("value1")
                .value("value2").build();

        return builder.additionalType(myOwnEnum);
    }

By using the `@Observer` you can add anything to the Schema builder.

| For the Observer to work, you need to enable events. In `application.properties`, add the following: `quarkus.smallrye-graphql.events.enabled=true`.

## Adapting

### Adapt to Scalar

Another SmallRye specific experimental feature, allows you to map an existing scalar (that is mapped by the implementation to a certain Java type) to another type, or to map complex object, that would typically create a `Type` or `Input` in GraphQL, to an existing scalar.

#### Adapting an existing Scalar to another type:

    public class Movie {

        @AdaptToScalar(Scalar.Int.class)
        Long idLongThatShouldChangeToInt;

        // ....
    }

Above will adapt the `Long` java type to an `Int` Scalar type, rather than the default `BigInteger`.

#### Adapting a complex object to a Scalar type:

    public class Person {

        @AdaptToScalar(Scalar.String.class)
        Phone phone;

        // ....
    }

This will, rather than creating a `Type` or `Input` in GraphQL, map to a String scalar.

To be able to do the above, the `Phone` object needs to have a constructor that takes a String (or `Int` / `Date` / etc.), or have a setter method for the String (or `Int` / `Date` / etc.), or have a `fromString` (or `fromInt` / `fromDate` - depending on the Scalar type) static method.

For example:

    public class Phone {

        private String number;

        // Getters and setters....

        public static Phone fromString(String number) {
            Phone phone = new Phone();
            phone.setNumber(number);
            return phone;
        }
    }

See more about the `@AdaptToScalar` feature in the JavaDoc.

### Adapt with

Another option for more complex cases is to provide an Adapter. You can then do the mapping yourself in the adapter.

See more about the `AdaptWith` feature in the JavaDoc.

For example:

        public class Profile {
            // Map this to an email address
            @AdaptWith(AddressAdapter.class)
            public Address address;

            // other getters/setters...
        }

        public class AddressAdapter implements Adapter<EmailAddress, Address> {

            @Override
            public Address from(EmailAddress email) {
                Address a = new Address();
                a.addressType = AddressType.email;
                a.addLine(email.getValue());
                return a;
            }

            @Override
            public EmailAddress to(Address address) {
                if (address != null && address.addressType != null && address.addressType.equals(AddressType.email)) {
                    return new EmailAddress(address.lines.get(0));
                }
                return null;
            }
        }

| `@JsonbTypeAdapter` is also supported.

### Built-in support for Maps

By default, due to the fact that maps are hard to model in a schema (as the keys and values can be dynamic at runtime) GraphQL does not support maps by default. Using the above adaption, `Map` support is added for Quarkus and are mapped to an `Entry<Key,Value>` with an optional key parameter. This allows you to return a map, and optionally query it by key.

Example:

        @Query
        public Map<ISO6391, Language> language() {
            return languageService.getLanguages();
        }

        public enum ISO6391 {
            af,
            en,
            de,
            fr
        }

        public class Language {
            private ISO6391 iso6391;
            private String nativeName;
            private String enName;
            private String please;
            private String thankyou;

            // Getters & Setters
        }

| The key and value object can be any of Enum, Scalar or Complex object

You can now query the whole map with all the fields:

    {
      language{
        key
        value {
          enName
          iso6391
          nativeName
          please
          thankyou
        }
      }
    }

This will return a result like this for example:

    {
      "data": {
        "language": [
          {
            "key": "fr",
            "value": {
              "enName": "french",
              "iso6391": "fr",
              "nativeName": "français",
              "please": "s'il te plaît",
              "thankyou": "merci"
            }
          },
          {
            "key": "af",
            "value": {
              "enName": "afrikaans",
              "iso6391": "af",
              "nativeName": "afrikaans",
              "please": "asseblief",
              "thankyou": "dankie"
            }
          },
          {
            "key": "de",
            "value": {
              "enName": "german",
              "iso6391": "de",
              "nativeName": "deutsch",
              "please": "bitte",
              "thankyou": "danke dir"
            }
          },
          {
            "key": "en",
            "value": {
              "enName": "english",
              "iso6391": "en",
              "nativeName": "english",
              "please": "please",
              "thankyou": "thank you"
            }
          }
        ]
      }
    }

You can also query by key

    {
      language (key:af){
        value {
          please
          thankyou
        }
      }
    }

That will return only that value in the map:

    {
      "data": {
        "language": [
          {
            "value": {
              "please": "asseblief",
              "thankyou": "dankie"
            }
          }
        ]
      }
    }

| The default map adapter can to overridden with our own implementation.

## Error code

You can add an error code on the error output in the GraphQL response by using the (SmallRye specific) `@ErrorCode`:

    @ErrorCode("some-business-error-code")
    public class SomeBusinessException extends RuntimeException {
        // ...
    }

When `SomeBusinessException` occurs, the error output will contain the Error code:

    {
        "errors": [
            {
                "message": "Unexpected failure in the system. Jarvis is working to fix it.",
                "locations": [
                    {
                        "line": 2,
                        "column": 3
                    }
                ],
                "path": [
                    "annotatedCustomBusinessException"
                ],
                "extensions": {
                    "exception": "io.smallrye.graphql.test.apps.error.api.ErrorApi$AnnotatedCustomBusinessException",
                    "classification": "DataFetchingException",
                    "code": "some-business-error-code" (1)
                }
            }
        ],
        "data": {
            ...
        }
    }

1 | The error code

## Additional Notes

If you are using the `smallrye-graphql` extension and the `micrometer` metrics extension is present and metrics are enabled, you may encounter a `java.lang.NoClassDefFoundError` as some versions of the `smallrye-graphql` extension have runtime requirements on the Microprofile Metrics API. Add the following MicroProfile Metrics API dependency to resolve the issue:

pom.xml

    <dependency>
        <groupId>org.eclipse.microprofile.metrics</groupId>
        <artifactId>microprofile-metrics-api</artifactId>
    </dependency>

build.gradle

    implementation("org.eclipse.microprofile.metrics:microprofile-metrics-api")

## Conclusion

SmallRye GraphQL enables clients to retrieve the exact data that is required preventing `Over-fetching` and `Under-fetching`.

The GraphQL API can be expanded without breaking previous queries enabling easy API `evolution`.

## Configuration Reference

Configuration property fixed at build time - All other configuration properties are overridable at runtime

Configuration property | Type | Default
--- | --- | ---
`quarkus.smallrye-graphql.root-path` The rootPath under which queries will be served. Default to graphql By default, this value will be resolved as a path relative to `${quarkus.http.root-path}`. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_ROOT_PATH` | string | `graphql`
`quarkus.smallrye-graphql.federation.enabled` Enable Apollo Federation. If this value is unspecified, then federation will be enabled automatically if any GraphQL Federation annotations are detected in the application. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_FEDERATION_ENABLED` | boolean |
`quarkus.smallrye-graphql.federation.batch-resolving-enabled` Enable batch resolving for federation. Disabled by default. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_FEDERATION_BATCH_RESOLVING_ENABLED` | boolean |
`quarkus.smallrye-graphql.metrics.enabled` Enable metrics. By default, this is false. If set to true, a metrics extension is required. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_METRICS_ENABLED` | boolean |
`quarkus.smallrye-graphql.tracing.enabled` Enable tracing. By default, this will be enabled if the tracing extension is added. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_TRACING_ENABLED` | boolean |
`quarkus.smallrye-graphql.events.enabled` Enable eventing. Allow you to receive events on bootstrap and execution. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_EVENTS_ENABLED` | boolean | `false`
`quarkus.smallrye-graphql.nonblocking.enabled` Enable non-blocking support. Default is true. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_NONBLOCKING_ENABLED` | boolean |
`quarkus.smallrye-graphql.http.get.enabled` Enable GET Requests. Allow queries via HTTP GET. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_HTTP_GET_ENABLED` | boolean |
`quarkus.smallrye-graphql.http.post.queryparameters.enabled` Enable Query parameter on POST Requests. Allow POST request to override or supply values in a query parameter. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_HTTP_POST_QUERYPARAMETERS_ENABLED` | boolean |
`quarkus.smallrye-graphql.auto-name-strategy` Change the type naming strategy. All possible strategies are: default, merge-inner-class, full Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_AUTO_NAME_STRATEGY` | string | `Default`
`quarkus.smallrye-graphql.error-extension-fields` List of extension fields that should be included in the error response. By default, none will be included. Examples of valid values include [exception,classification,code,description,validationErrorType,queryPath] Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_ERROR_EXTENSION_FIELDS` | list of string |
`quarkus.smallrye-graphql.default-error-message` The default error message that will be used for hidden exception messages. Defaults to "Server Error" Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_DEFAULT_ERROR_MESSAGE` | string |
`quarkus.smallrye-graphql.print-data-fetcher-exception` Print the data fetcher exception to the log file. Default `true` in dev and test mode, default `false` in prod. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_PRINT_DATA_FETCHER_EXCEPTION` | boolean |
`quarkus.smallrye-graphql.schema-available` Make the schema available over HTTP. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_SCHEMA_AVAILABLE` | boolean | `true`
`quarkus.smallrye-graphql.schema-include-scalars` Include the Scalar definitions in the schema. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_SCHEMA_INCLUDE_SCALARS` | boolean | `false`
`quarkus.smallrye-graphql.schema-include-schema-definition` Include the schema internal definition in the schema. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_SCHEMA_INCLUDE_SCHEMA_DEFINITION` | boolean | `false`
`quarkus.smallrye-graphql.schema-include-directives` Include Directives in the schema. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_SCHEMA_INCLUDE_DIRECTIVES` | boolean | `false`
`quarkus.smallrye-graphql.schema-include-introspection-types` Include Introspection Types in the schema. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_SCHEMA_INCLUDE_INTROSPECTION_TYPES` | boolean | `false`
`quarkus.smallrye-graphql.log-payload` Log the payload (and optionally variables) to System out. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_LOG_PAYLOAD` | `off`, `query-only`, `query-and-variables` | `off`
`quarkus.smallrye-graphql.unwrap-exceptions` Exceptions that should be unwrapped (class names). Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_UNWRAP_EXCEPTIONS` | list of string |
`quarkus.smallrye-graphql.websocket-subprotocols` Subprotocols that should be supported by the server for graphql-over-websocket use cases. Allowed subprotocols are "graphql-ws" and "graphql-transport-ws". By default, both are enabled. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_WEBSOCKET_SUBPROTOCOLS` | list of string |
`quarkus.smallrye-graphql.parser-capture-ignored-chars` Set to true if ignored chars should be captured as AST nodes. Default to false Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_PARSER_CAPTURE_IGNORED_CHARS` | boolean |
`quarkus.smallrye-graphql.parser-capture-line-comments` Set to true if `graphql.language.Comment`s should be captured as AST nodes Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_PARSER_CAPTURE_LINE_COMMENTS` | boolean |
`quarkus.smallrye-graphql.parser-capture-source-location` Set to true true if `graphql.language.SourceLocation`s should be captured as AST nodes. Default to true Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_PARSER_CAPTURE_SOURCE_LOCATION` | boolean |
`quarkus.smallrye-graphql.parser-max-tokens` The maximum number of raw tokens the parser will accept, after which an exception will be thrown. Default to 15000 Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_PARSER_MAX_TOKENS` | int |
`quarkus.smallrye-graphql.parser-max-whitespace-tokens` The maximum number of raw whitespace tokens the parser will accept, after which an exception will be thrown. Default to 200000 Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_PARSER_MAX_WHITESPACE_TOKENS` | int |
`quarkus.smallrye-graphql.instrumentation-query-complexity` Abort a query if the total number of data fields queried exceeds the defined limit. Default to no limit Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_INSTRUMENTATION_QUERY_COMPLEXITY` | int |
`quarkus.smallrye-graphql.instrumentation-query-depth` Abort a query if the total depth of the query exceeds the defined limit. Default to no limit Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_INSTRUMENTATION_QUERY_DEPTH` | int |
`quarkus.smallrye-graphql.extra-scalars` Additional scalars to register in the schema. These are taken from the `graphql-java-extended-scalars` library. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_EXTRA_SCALARS` | list of `uuid` |
`quarkus.smallrye-graphql.ui.enable` If GraphQL UI should be enabled. By default, GraphQL UI is enabled if it is included (see `always-include`). Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_UI_ENABLE` | boolean | `true`
`quarkus.smallrye-graphql.field-visibility` Specifies the field visibility for the GraphQL schema. This configuration item allows you to define comma-separated list of patterns (GraphQLType.GraphQLField). These patterns are used to determine which fields should be excluded from the schema. Special value `no-introspection` will disable introspection fields. For more info see graphql-java documentation Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_FIELD_VISIBILITY` | string | `default`
`quarkus.smallrye-graphql.exclude-null-fields-in-responses` Excludes all the 'null' fields in the GraphQL response’s `data` field, except for the non-successfully resolved fields (errors). Disabled by default. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_EXCLUDE_NULL_FIELDS_IN_RESPONSES` | boolean |
`quarkus.smallrye-graphql.show-runtime-exception-message` List of Runtime Exceptions class names that should show the error message. By default, Runtime Exception messages will be hidden and a generic `Server Error` message will be returned. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_SHOW_RUNTIME_EXCEPTION_MESSAGE` | list of string |
`quarkus.smallrye-graphql.hide-checked-exception-message` List of Checked Exceptions class names that should hide the error message. By default, Checked Exception messages will show the exception message. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_HIDE_CHECKED_EXCEPTION_MESSAGE` | list of string |
SmallRye GraphQL UI configuration | Type | Default
`quarkus.smallrye-graphql.ui.root-path` The path where GraphQL UI is available. The value `/` is not allowed as it blocks the application from serving anything else. By default, this URL will be resolved as a path relative to `${quarkus.http.non-application-root-path}`. Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_UI_ROOT_PATH` | string | `graphql-ui`
`quarkus.smallrye-graphql.ui.always-include` Always include the UI. By default, this will only be included in dev and test. Setting this to true will also include the UI in Prod Environment variable: `QUARKUS_SMALLRYE_GRAPHQL_UI_ALWAYS_INCLUDE` | boolean | `false`