CopyToContextParameter

The extension point CopyToContextParameter offers the ability to declare additional parameters, for example, HTTP headers, which then will be added automatically to the GraphQL context during graphql queries.

public class SecurityTokenContextParameter implements CopyToContextParameter<String, String> {

  public static final String HEADER_NAME = "X-SECURITY-TOKEN";
  public static final String NAME_IN_CONTEXT = "securityToken";

  @Override
  public String getName() {
    return HEADER_NAME;
  }

  @Override
  public String getNameInContext() {
    return NAME_IN_CONTEXT;
  }

  @Override
  public ContextValueOrigin getValueOrigin() {
    return ContextValueOrigin.REQUEST_HEADER;
  }

  @Override
  public boolean previewOnly() {
    return false;
  }

}

// Bean factory in the plugin configuration class
@Bean
public SecurityTokenContextParameter securityTokenContextParameter() {
  return new SecurityTokenContextParameter(settingsService);
}

Implementations of this extension point can also be provided within CaasConfig, using the qualifier PluginSupport#QUALIFIER_CAAS_COPY_TO_CONTEXT_PARAMETER at bean creation.

FilterPredicate

Implementations of FilterPredicate are also fed to the ModelMapper during the server start. They can also be provided within CaasConfig, using the qualifier PluginSupport#QUALIFIER_CAAS_FILTER_PREDICATE at bean creation. See Section 4.6, “Filter Predicates” for details.

public class SecurityTokenFilterPredicate implements FilterPredicate<Object> {

  private static final String SERVER_SECRET_TOKEN = "secret-hash-set-by-environment";

  public boolean test(DataFetchingEnvironment dataFetchingEnvironment, Object o) {
    String securityToken = (String) ((Map<String, Object>) dataFetchingEnvironment.getContext()).get(SecurityTokenContextParameter.NAME_IN_CONTEXT);
    return (securityToken != null && SERVER_SECRET_TOKEN.equalsIgnoreCase(securityToken));
  }
}

// Bean factory in the plugin configuration class
@Bean
public SecurityTokenFilterPredicate securityTokenFilterPredicate(
  ContextVariableValueService contextVariableValueService
) {
  return new SecurityTokenFilterPredicate(contextVariableValueService);
}

PluginSchemaAdapterFactory

In conjunction with the plugin resource loading feature for GraphQL schema extensions, so called schema adapters can be invoked to resolve schema properties via the fetch directive using the Spring Expression Language (SpEL). While the out of the box schema adapters can be used without any problems, named schema adapters from within a plugin have to implement the extension point PluginSchemaAdapterFactory, in order to define the adapters name from within the plugin.

Note, that plugin schema adapters can only be used within the SpEL context of the GraphQL schema. For more information about adapters, please see Section 4.8, “Adapter”. An example can be found in the JavaDocs at PluginSchemaAdapterFactory.

CustomScalarType

The extension point CustomScalarType allows the definition of custom scalar types in plugins. Note, that to use a custom scalar type, you need to define it in the GraphQL schema as well as instantiate an instance of CustomScalarType as a Spring bean in the PluginConfiguration.

The custom scalar types of plugins are provided as a Spring bean by the Headless Server using the qualifier PluginSupport#QUALIFIER_PLUGIN_CUSTOM_SCALARS

CaasWiringFactory

This extension point allows to define additional WiringFactory implementations in a plugin by implementing CaasWiringFactory.

Implementations of this extension point are provided as a Spring bean using the qualifier PluginSupport#QUALIFIER_PLUGIN_WIRING_FACTORIES.

All WiringFactory implementations, which are not part of a plugin must be marked with the qualifier PluginSupport#QUALIFIER_CAAS_WIRING_FACTORIES in order to distinguish them from the predicates created inside of Headless Server and merge them with the ones implemented in plugins.

LinkComposer

This extension point allows to define additional LinkComposer implementations in a plugin by implementing the interface UriLinkComposer for URI links or GrapQLLinkComposer for GraphQL links.

Implementations of this extension point can be accessed using the qualifier PluginSupport#QUALIFIER_PLUGIN_LINK_COMPOSERS_URI and PluginSupport#QUALIFIER_PLUGIN_LINK_COMPOSERS_GRAPHQL at bean creation.

The default implementations of LinkComposer are then merged with the ones implemented in plugins.

CustomFilterQuery

A CustomFilterQuery provides the ability to add additional filter queries to the Solr query, using the customFilterQueries parameter of the GraphQL search query.

Implementations of this type are provided as a Spring bean via a Spring configuration class, e.g. CaasConfig or via the means of a plugin.

For details about the implementation please see Section 6.3, “Custom Filter Queries”.