ronald-d-rogers / graphql-java-servlet

Servlet endpoint for GraphQL Java

GraphQL Servlet

This module implements a GraphQL Java Servlet. It also supports Relay.js, Apollo and OSGi out of the box.

Downloading

You can download releases from maven central:

repositories {
    mavenCentral()
}

dependencies {
    compile 'com.graphql-java:graphql-java-servlet:4.6.1'
}

<dependency>
    <groupId>com.graphql-java</groupId>
    <artifactId>graphql-java-servlet</artifactId>
    <version>4.6.1</version>
</dependency>

Usage

The servlet supports the following request formats:

• GET request to ../schema.json: Get the result of an introspection query.
• GET request with query parameters (query only, no mutation):
  • query
  • operationName (optional)
  • variables (optional)
• POST body JSON object with fields:
  • query
  • operationName (optional)
  • variables (optional)
• POST multipart part named "graphql" containing JSON object with fields:
  • query
  • operationName (optional)
  • variables (optional)
• POST multipart parts named "query", "operationName" (optional), and "variables" (optional)

Standalone servlet

The simplest form of the servlet takes a graphql-java GraphQLSchema and an ExecutionStrategy:

GraphQLServlet servlet = new SimpleGraphQLServlet(schema, executionStrategy);

// or

GraphQLServlet servlet = new SimpleGraphQLServlet(schema, executionStrategy, operationListeners, servletListeners);

Servlet Listeners

You can also add servlet listeners to an existing servlet. These listeners provide hooks into query execution (before, success, failure, and finally) and servlet execution (before, success, error, and finally):

servlet.addListener(new GraphQLServletListener() {
    @Override
    GraphQLServletListener.RequestCallback onRequest(HttpServletRequest request, HttpServletResponse response) {

        return new GraphQLServletListener.RequestCallback() {
            @Override
            void onSuccess(HttpServletRequest request, HttpServletResponse response) {

            }

            @Override
            void onError(HttpServletRequest request, HttpServletResponse response, Throwable throwable) {

            }

            @Override
            void onFinally(HttpServletRequest request, HttpServletResponse response) {

            }
        }
    }

    @Override
    GraphQLServletListener.OperationCallback onOperation(GraphQLContext context, String operationName, String query, Map<String, Object> variables) {

        return new GraphQLServletListener.OperationCallback() {
            @Override
            void onSuccess(GraphQLContext context, String operationName, String query, Map<String, Object> variables, Object data) {

            }

            @Override
            void onError(GraphQLContext context, String operationName, String query, Map<String, Object> variables, Object data, List<GraphQLError> errors) {

            }

            @Override
            void onFinally(GraphQLContext context, String operationName, String query, Map<String, Object> variables, Object data) {

            }
        }
    }
})

Relay.js support

Relay.js support is provided by the EnhancedExecutionStrategy of graphql-java-annotations. You MUST pass this execution strategy to the servlet for Relay.js support.

This is the default execution strategy for the OsgiGraphQLServlet, and must be added as a dependency when using that servlet.

Apollo support

Query batching is supported, no configuration required.

Spring Framework support

To use the servlet with Spring Framework, either use the Spring Boot starter or simply define a ServletRegistrationBean in a web app:

@Bean
ServletRegistrationBean graphQLServletRegistrationBean(GraphQLSchema schema, ExecutionStrategy executionStrategy, List<GraphQLOperationListener> operationListeners) {
    return new ServletRegistrationBean(new SimpleGraphQLServlet(schema, executionStrategy, operationListeners), "/graphql");
}

OSGI support

The OsgiGraphQLServlet uses a "provider" model to supply the servlet with the required objects:

• GraphQLQueryProvider: Provides query fields to the GraphQL schema.
• GraphQLMutationProvider: Provides mutation fields to the GraphQL schema.
• GraphQLTypesProvider: Provides type information to the GraphQL schema.
• ExecutionStrategyProvider: Provides an execution strategy for running each query.
• GraphQLContextBuilder: Builds a context for running each query.

Examples

You can now find some example on how to use graphql-java-servlet.

OSGi Examples

Requirements

The OSGi examples use Maven as a build tool because it requires plugins that are not (yet) available for Gradle. Therefore you will need Maven 3.2+.

Building & running the OSGi examples

You can build the OSGi examples sub-projects by simply executing the following command from the examples/osgi directory:

mvn clean install

This will generate a complete Apache Karaf distribution in the following files:

 examples/osgi/apache-karaf-package/target/graphql-java-servlet-osgi-examples-apache-karaf-package-VERSION.tar.gz(.zip)

You can simply uncompress this file and launch the OSGi server using the command from the uncompressed directory:

bin/karaf

You should then be able to access the GraphQL endpoint at the following URL once the server is started:

http://localhost:8181/graphql/schema.json

If you see the JSON result of an introspection query, then all is ok. If not, check the data/log/karaf.log file for any errors.

We also provide a script file to do all of the building and running at once (only for Linux / MacOS ):

./buildAndRun.sh

Deploying inside Apache Karaf server

You can use the graphql-java-servlet as part of an Apache Karaf feature, as you can see in the example project here:

• pom.xml

And here is a sample src/main/feature/feature.xml file to add some dependencies on other features:

• feature.xml

Example GraphQL provider implementation

Here's an example of a GraphQL provider that implements three interfaces at the same time.

• ExampleGraphQLProvider