siathalysedi / apollo-client-maven-plugin

Generate a Java GraphQL client based on introspection data and predefined queries.

Apollo GraphQL Client Code Generation Maven Plugin

Usage

A full usage example can be found in the test project

Getting Started

NOTE: This plugin requires a nodejs environment to execute the bundled apollo-codegen node module.

1. Add the apollo runtime library and guava to your project's depedencies:

   <dependency>
       <groupId>com.apollographql.apollo</groupId>
       <artifactId>apollo-runtime</artifactId>
       <version>0.4.0</version>
   </dependency>

2. Add the code generator plugin to your project's build (if codegen is desired):

   <plugin>
       <groupId>com.coxautodev</groupId>
       <artifactId>apollo-client-maven-plugin</artifactId>
       <version>1.1.0</version>
       <executions>
           <execution>
               <goals>
                   <goal>generate</goal>
               </goals>
               <configuration>
                   <basePackage>com.my.package.graphql.client</basePackage>
               </configuration>
           </execution>
       </executions>
   </plugin>

3. Create a file src/main/graphql/schema.json with the JSON results of an introspection query
4. Create files for each query you'd like to generate classes for under src/main/graphql:
   1. Query file names must match the name of the query they contain
   2. Query files must end with .graphql
   3. Any subdirectories under src/main/graphql are treated as extra package names to append to packageName in the plugin config.
5. Run mvn clean generate-sources to generate classes for your queries.

Configuration Options

All plugin options and their defaults:

<configuration>
    <outputDirectory>${project.build.directory}/generated-sources/graphql-client</outputDirectory>
    <basePackage>com.example.graphql.client</basePackage>
    <schemaFile>${project.basedir}/src/main/graphql/schema.json</schemaFile>
    <addSourceRoot>true</addSourceRoot>
</configuration>

Using the Client

Assuming a file named src/main/graphql/GetBooks.graphql is defined that contains a query named GetBooks against the given schema.json, the following code demonstrates how that query could be executed.

ApolloClient client = ApolloClient.builder()
    .serverUrl("https://example.com/graphql")
    .okHttpClient(new OkHttpClient.Builder()
        .addInterceptor(new Interceptor() {
            @Override
            Response intercept(Interceptor.Chain chain) throws IOException {
                chain.proceed(chain.request().newBuilder().addHeader("Authorization", "Basic cnllYnJ5ZTpidWJibGVzMTIz").build())
            }
        })
        .build())
    .build()
    
Optional<GetBooks.Data> data = client.newCall(new GetBooks()).execute().data()

if(data.isPresent()) {
    System.out.println("Book count: " + data.get().books().size());
}

Properties specified as nullable in the schema will have an java 8 java.util.optional type.