Make Http request and response headers available to repositories and …

…modules #94

HttpRequestContextAware introduced. Instances loaded by ServiceDiscovery are checked for this interfaced and setup accordingly.

crnk-core/src/main/java/io/crnk/core/boot/CrnkBoot.java

@@ -1,14 +1,10 @@
 package io.crnk.core.boot;
 
-import java.util.LinkedList;
-import java.util.List;
-import java.util.Map;
-
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.SerializationFeature;
-
 import io.crnk.core.engine.error.JsonApiExceptionMapper;
 import io.crnk.core.engine.filter.DocumentFilter;
+import io.crnk.core.engine.http.HttpRequestContextAware;
 import io.crnk.core.engine.information.resource.ResourceFieldInformationProvider;
 import io.crnk.core.engine.information.resource.ResourceFieldNameTransformer;
 import io.crnk.core.engine.internal.dispatcher.ControllerRegistry;
@@ -26,11 +22,7 @@
 import io.crnk.core.engine.properties.NullPropertiesProvider;
 import io.crnk.core.engine.properties.PropertiesProvider;
 import io.crnk.core.engine.query.QueryAdapterBuilder;
-import io.crnk.core.engine.registry.DefaultResourceRegistryPart;
-import io.crnk.core.engine.registry.HierarchicalResourceRegistryPart;
-import io.crnk.core.engine.registry.RegistryEntry;
-import io.crnk.core.engine.registry.ResourceRegistry;
-import io.crnk.core.engine.registry.ResourceRegistryPart;
+import io.crnk.core.engine.registry.*;
 import io.crnk.core.engine.url.ConstantServiceUrlProvider;
 import io.crnk.core.engine.url.ServiceUrlProvider;
 import io.crnk.core.module.Module;
@@ -58,6 +50,10 @@
 import io.crnk.legacy.repository.information.DefaultResourceRepositoryInformationBuilder;
 import net.jodah.typetools.TypeResolver;
 
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+
 /**
  * Facilitates the startup of Crnk in various environments (Spring, CDI,
  * JAX-RS, etc.).
@@ -132,6 +128,7 @@ public void setServiceLocator(JsonServiceLocator serviceLocator) {
 	 */
 	public void addModule(Module module) {
 		checkNotConfiguredYet();
+		setupInstance(module);
 		moduleRegistry.addModule(module);
 	}
 
@@ -268,16 +265,16 @@ public void setupModule(ModuleContext context) {
 		module.addRepositoryInformationBuilder(new DefaultRelationshipRepositoryInformationBuilder());
 
 		AnnotationResourceInformationBuilder resourceInformationBuilder =
-			new AnnotationResourceInformationBuilder(resourceFieldNameTransformer, getResourceFieldInformationProviders());
+				new AnnotationResourceInformationBuilder(resourceFieldNameTransformer, getResourceFieldInformationProviders());
 		module.addResourceInformationBuilder(resourceInformationBuilder);
 
-		for (JsonApiExceptionMapper<?> exceptionMapper : serviceDiscovery.getInstancesByType(JsonApiExceptionMapper.class)) {
+		for (JsonApiExceptionMapper<?> exceptionMapper : getInstancesByType(JsonApiExceptionMapper.class)) {
 			module.addExceptionMapper(exceptionMapper);
 		}
-		for (DocumentFilter filter : serviceDiscovery.getInstancesByType(DocumentFilter.class)) {
+		for (DocumentFilter filter : getInstancesByType(DocumentFilter.class)) {
 			module.addFilter(filter);
 		}
-		for (Object repository : serviceDiscovery.getInstancesByType(Repository.class)) {
+		for (Object repository : getInstancesByType(Repository.class)) {
 			setupRepository(module, repository);
 		}
 		for (Object repository : serviceDiscovery.getInstancesByAnnotation(JsonApiResourceRepository.class)) {
@@ -295,6 +292,21 @@ public void setupModule(ModuleContext context) {
 		moduleRegistry.setPropertiesProvider(propertiesProvider);
 	}
 
+	private <T> List<T> getInstancesByType(Class<T> clazz) {
+		List<T> instancesByType = serviceDiscovery.getInstancesByType(clazz);
+		for (T instance : instancesByType) {
+			setupInstance(instance);
+		}
+		return instancesByType;
+	}
+
+	private <T> void setupInstance(T instance) {
+		if (instance instanceof HttpRequestContextAware) {
+			HttpRequestContextAware aware = (HttpRequestContextAware) instance;
+			aware.setHttpRequestContextProvider(moduleRegistry.getHttpRequestContextProvider());
+		}
+	}
+
 	private void setupRepository(SimpleModule module, Object repository) {
 		if (repository instanceof ResourceRepository) {
 			ResourceRepository resRepository = (ResourceRepository) repository;
@@ -319,7 +331,7 @@ private void setupRepository(SimpleModule module, Object repository) {
 	}
 
 	private void addModules() {
-		List<Module> modules = serviceDiscovery.getInstancesByType(Module.class);
+		List<Module> modules = getInstancesByType(Module.class);
 		for (Module module : modules) {
 			moduleRegistry.addModule(module);
 		}

crnk-core/src/main/java/io/crnk/core/engine/http/HttpRequestContextAware.java

@@ -0,0 +1,9 @@
+package io.crnk.core.engine.http;
+
+/**
+ * Can be implemented by repositories to get access to request parameters.
+ */
+public interface HttpRequestContextAware {
+
+	void setHttpRequestContextProvider(HttpRequestContextProvider requestContextProvider);
+}

crnk-core/src/test/java/io/crnk/core/engine/http/HttpRequestContextAwareTest.java

@@ -0,0 +1,31 @@
+package io.crnk.core.engine.http;
+
+import io.crnk.core.boot.CrnkBoot;
+import io.crnk.core.engine.url.ConstantServiceUrlProvider;
+import io.crnk.core.module.Module;
+import io.crnk.core.module.discovery.ReflectionsServiceDiscovery;
+import io.crnk.core.resource.registry.ResourceRegistryBuilderTest;
+import org.junit.Test;
+import org.mockito.Mockito;
+
+import java.io.IOException;
+
+public class HttpRequestContextAwareTest {
+
+	interface HttTestModule extends Module, HttpRequestContextAware {
+
+	}
+
+	@Test
+	public void check() throws IOException {
+		HttTestModule testModule = Mockito.mock(HttTestModule.class);
+
+		CrnkBoot boot = new CrnkBoot();
+		boot.setServiceUrlProvider(new ConstantServiceUrlProvider("http://localhost:8080"));
+		boot.setServiceDiscovery(new ReflectionsServiceDiscovery(ResourceRegistryBuilderTest.TEST_MODELS_PACKAGE));
+		boot.addModule(testModule);
+		boot.boot();
+
+		Mockito.verify(testModule, Mockito.times(1)).setHttpRequestContextProvider(Mockito.any(HttpRequestContextProvider.class));
+	}
+}

crnk-documentation/src/docs/asciidoc/module_development.adoc

@@ -52,6 +52,20 @@ query those `ResourceFilter` and only display information about resources and fi
 of the current re quest. The `ResourceFilterDirectory` makes use of per-request caching as the information
 may be accessed repeatedly for a request.
 
+## Access to HTTP layer
+
+`HttpRequestContext` resp. `HttpRequestContextProvider` provides access to the HTTP requests. Most
+notably to get and set HTTP request and response headers. In many cases, the underlying
+implementation like JAXRS or Servlet provides that access as well. With `HttpRequestContext`
+there is an implementation that is independent of that implementation. As such it is well suited
+for module development, in particular for request filtering. A typical use case is to set and
+access security headers.
+
+`HttpRequestContextProvider.getRequestContext` returns the request context for the currently
+active request. Modules have access to `HttpRequestContextProvider` trough the `ModuleContext`.
+Repositories, filters and modules can implement `HttpRequestContextAware` to get
+access to `HttpRequestContextProvider`.
+
 
 ## Integrate third-party data stores