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Dynamic client introduction and basic usage

A Java GraphQL client. The main difference from the typesafe client is that while the typesafe client behaves like a typesafe proxy very similar to the MicroProfile REST Client, the dynamic client is more like the JAX-RS client from the package. Instead of working with model classes directly, the dynamic client focuses on programmatically working with GraphQL documents representing GraphQL requests and responses. It still offers the option to convert between documents and model classes when necessary.

In the current implementation, Vert.x HTTP client is used for handling the underlying traffic.

Basic Usage

Given the following GraphQL service on the server side:

class SuperHeroesApi {
    List<SuperHero> allHeroesIn(String location) {
        // ....

class SuperHero {
    private String name;
    private List<String> superPowers;

Such service can be queried this way:

package examples.dynamicclient;

import examples.typesafeclient.SuperHero;
import io.smallrye.graphql.client.Response;
import io.smallrye.graphql.client.core.Document;
import io.smallrye.graphql.client.dynamic.api.DynamicGraphQLClient;

import javax.inject.Inject;
import javax.json.JsonArray;
import java.util.List;
import java.util.concurrent.ExecutionException;

import static io.smallrye.graphql.client.core.Argument.arg;
import static io.smallrye.graphql.client.core.Argument.args;
import static io.smallrye.graphql.client.core.Document.document;
import static io.smallrye.graphql.client.core.Field.field;
import static io.smallrye.graphql.client.core.Operation.operation;

public class MyClientUsage {

    DynamicGraphQLClient client;

    public void execute() throws ExecutionException, InterruptedException {
        Document document = document(   // <1>
                args(arg("location", "Outer Space")),
        Response response = client.executeSync(document); // <2>

        JsonArray heroesArray = response.getData().getJsonArray("allHeroesIn");  // <3>
        List<SuperHero> heroes = response.getList(SuperHero.class, "allHeroesIn"); // <4>
  • <1> Creating the document representing the request. We used static imports to make the code easy to read, they all come from the classes in the io.smallrye.graphql.client.core package.

  • <2> Executing the request. You can either do that in a blocking way, or request a Uni if you prefer the reactive style.

  • <3> Obtaining the resulting list of heroes as a JsonArray.

  • <4> Obtaining the resulting list of heroes as instances of the model class. This is optional, you can continue working with the data as a JsonArray if you prefer.

Initializing the client instance

There are two ways to obtain a client instance.

Using CDI injection where the configuration values are defined in system properties:

DynamicGraphQLClient client;

// assuming that this system property exists:
// superheroes/mp-graphql/url=

Programmatically using a builder:

DynamicGraphQLClient client = DynamicGraphQLClientBuilder.newBuilder()

Configuration properties

These properties apply when you’re using CDI to inject named client instances (the first example in the previous section).

  • CLIENT_NAME/mp-graphql/url - defines the URL where the client should connect

  • CLIENT_NAME/mp-graphql/header/KEY - this property declares that the client will add a HTTP header named KEY to all requests (with a value being the value of this property)