DATAREST-95 - Add support for PATCH to partially update entities.

Added general support for HTTP PATCH to partially update entities and amend property resources.

.gitignore

@@ -8,4 +8,5 @@ target/
 .project
 .settings
 *.log
-vf.gf.*
+vf.gf.*
+out/

spring-data-rest-core/src/main/java/org/springframework/data/rest/core/support/DomainObjectMerger.java

@@ -61,7 +61,7 @@ public class DomainObjectMerger {
 	 * @param from can be {@literal null}.
 	 * @param target can be {@literal null}.
 	 */
-	public void merge(Object from, Object target) {
+	public void merge(Object from, Object target, final MergeNullPolicy nullPolicy) {
 
 		if (null == from || null == target) {
 			return;
@@ -88,7 +88,9 @@ public class DomainObjectMerger {
 				}
 
 				if (!ObjectUtils.nullSafeEquals(sourceValue, targetValue)) {
-					targetWrapper.setProperty(persistentProperty, sourceValue);
+					if (nullPolicy == MergeNullPolicy.APPLY_NULLS || sourceValue != null) {
+						targetWrapper.setProperty(persistentProperty, sourceValue);
+					}
 				}
 			}
 		});
@@ -110,4 +112,15 @@ public class DomainObjectMerger {
 			}
 		});
 	}
+
+	/**
+	 * A switch on whether or not to ignore nulls.
+	 * NOTE: This could have been a simple boolean flag but the enumerated value clearly
+	 * denotes which version is being used.
+	 */
+	public static enum MergeNullPolicy {
+		APPLY_NULLS, IGNORE_NULLS;
+	}
+
+
 }

spring-data-rest-core/src/test/java/org/springframework/data/rest/core/support/DomainObjectMergerTests.java

@@ -57,7 +57,7 @@ public class DomainObjectMergerTests {
 		Person existingDomainObject = new Person("Frodo", "Baggins");
 
 		DomainObjectMerger merger = new DomainObjectMerger(repositories, conversionService);
-		merger.merge(incoming, existingDomainObject);
+		merger.merge(incoming, existingDomainObject, DomainObjectMerger.MergeNullPolicy.APPLY_NULLS);
 
 		assertThat(existingDomainObject.getFirstName(), equalTo(incoming.getFirstName()));
 		assertThat(existingDomainObject.getLastName(), equalTo(incoming.getLastName()));
@@ -76,7 +76,7 @@ public class DomainObjectMergerTests {
 		Person existingDomainObject = new Person("Frodo", "Baggins");
 
 		DomainObjectMerger merger = new DomainObjectMerger(repositories, conversionService);
-		merger.merge(incoming, existingDomainObject);
+		merger.merge(incoming, existingDomainObject, DomainObjectMerger.MergeNullPolicy.APPLY_NULLS);
 
 		assertThat(existingDomainObject.getFirstName(), equalTo(incoming.getFirstName()));
 		assertThat(existingDomainObject.getLastName(), equalTo(incoming.getLastName()));

spring-data-rest-webmvc/src/main/java/org/springframework/data/rest/webmvc/RepositoryEntityController.java

@@ -17,11 +17,15 @@ package org.springframework.data.rest.webmvc;
 
 import static org.springframework.data.rest.webmvc.ControllerUtils.*;
 
+import java.io.IOException;
 import java.net.URI;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.context.ApplicationEventPublisher;
@@ -57,10 +61,7 @@ import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.HttpRequestMethodNotSupportedException;
-import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.*;
-import org.springframework.web.bind.annotation.RequestMapping;
-import org.springframework.web.bind.annotation.RequestMethod;
-import org.springframework.web.bind.annotation.ResponseBody;
 
 /**
  * @author Jon Brisbin
@@ -238,7 +239,7 @@ class RepositoryEntityController extends AbstractRepositoryRestController implem
 			return createNewEntity(resourceInformation, incoming);
 		}
 
-		domainObjectMerger.merge(incoming.getContent(), domainObj);
+		domainObjectMerger.merge(incoming.getContent(), domainObj, DomainObjectMerger.MergeNullPolicy.APPLY_NULLS);
 
 		publisher.publishEvent(new BeforeSaveEvent(incoming.getContent()));
 		Object obj = invoker.invokeSave(domainObj);
@@ -255,6 +256,36 @@ class RepositoryEntityController extends AbstractRepositoryRestController implem
 		}
 	}
 
+	@RequestMapping(value = BASE_MAPPING + "/{id}", method = RequestMethod.PATCH, consumes = { "application/json" })
+	public ResponseEntity<? extends ResourceSupport> patchEntity(
+			RepositoryRestRequest request, PersistentEntityResource<Object> incoming,
+			@PathVariable String id) {
+
+		RepositoryInvoker invoker = request.getRepositoryInvoker();
+		if (null == invoker || !invoker.exposesSave() || !invoker.exposesFindOne()) {
+			return new ResponseEntity<Resource<?>>(HttpStatus.METHOD_NOT_ALLOWED);
+		}
+
+		Object domainObj = converter.convert(id, STRING_TYPE,
+				TypeDescriptor.valueOf(request.getPersistentEntity().getType()));
+		if (null == domainObj) {
+			return new ResponseEntity<Resource<?>>(HttpStatus.NOT_FOUND);
+		}
+
+		domainObjectMerger.merge(incoming.getContent(), domainObj, DomainObjectMerger.MergeNullPolicy.IGNORE_NULLS);
+
+		publisher.publishEvent(new BeforeSaveEvent(domainObj));
+		Object obj = invoker.invokeSave(domainObj);
+		publisher.publishEvent(new AfterSaveEvent(domainObj));
+
+		if (config.isReturnBodyOnUpdate()) {
+			return ControllerUtils.toResponseEntity(HttpStatus.OK, null, perAssembler.toResource(obj));
+		} else {
+			return ControllerUtils.toEmptyResponse(HttpStatus.NO_CONTENT);
+		}
+
+	}
+
 	@RequestMapping(value = BASE_MAPPING + "/{id}", method = RequestMethod.DELETE)
 	public ResponseEntity<?> deleteEntity(final RootResourceInformation resourceInformation, @PathVariable final String id)
 			throws ResourceNotFoundException, HttpRequestMethodNotSupportedException {

spring-data-rest-webmvc/src/test/java/org/springframework/data/rest/webmvc/AbstractWebIntegrationTests.java

@@ -37,6 +37,7 @@ import org.springframework.hateoas.Link;
 import org.springframework.hateoas.LinkDiscoverer;
 import org.springframework.hateoas.LinkDiscoverers;
 import org.springframework.hateoas.MediaTypes;
+import org.springframework.http.HttpMethod;
 import org.springframework.http.MediaType;
 import org.springframework.mock.web.MockHttpServletResponse;
 import org.springframework.test.context.ContextConfiguration;
@@ -47,6 +48,7 @@ import org.springframework.test.web.servlet.MvcResult;
 import org.springframework.test.web.servlet.ResultActions;
 import org.springframework.test.web.servlet.ResultMatcher;
 import org.springframework.test.web.servlet.request.MockHttpServletRequestBuilder;
+import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
 import org.springframework.test.web.servlet.setup.MockMvcBuilders;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
@@ -172,6 +174,18 @@ public abstract class AbstractWebIntegrationTests {
 		return request(response.getHeader("Location"));
 	}
 
+	protected MockHttpServletResponse patchAndGet(Link link, Object payload, MediaType mediaType) throws Exception {
+
+		String href = link.isTemplated() ? link.expand().getHref() : link.getHref();
+
+		MockHttpServletResponse response = mvc.perform(MockMvcRequestBuilders.request(HttpMethod.PATCH, href).//
+				content(payload.toString()).contentType(mediaType)).//
+				andExpect(status().isNoContent()).//
+				andReturn().getResponse();
+
+		return request(href);
+	}
+
 	protected MockHttpServletResponse deleteAndGet(Link link, MediaType mediaType) throws Exception {
 
 		String href = link.isTemplated() ? link.expand().getHref() : link.getHref();

spring-data-rest-webmvc/src/test/java/org/springframework/data/rest/webmvc/jpa/JpaWebTests.java

@@ -27,6 +27,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Scanner;
 
+import com.jayway.jsonpath.JsonPath;
 import org.junit.Before;
 import org.junit.Test;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -34,9 +35,11 @@ import org.springframework.core.io.ClassPathResource;
 import org.springframework.data.rest.core.mapping.ResourceMappings;
 import org.springframework.data.rest.webmvc.AbstractWebIntegrationTests;
 import org.springframework.hateoas.Link;
+import org.springframework.http.HttpMethod;
 import org.springframework.http.MediaType;
 import org.springframework.mock.web.MockHttpServletResponse;
 import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
 import org.springframework.transaction.annotation.Transactional;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
@@ -176,6 +179,34 @@ public class JpaWebTests extends AbstractWebIntegrationTests {
 		).andExpect(status().isCreated());
 	}
 
+	/**
+	 * @see DATAREST-95
+	 */
+	@Test
+	public void createThenPatch() throws Exception {
+
+		MockHttpServletResponse bilbo = postAndGet(new Link("/people/"),//
+				"{ \"firstName\" : \"Bilbo\", \"lastName\" : \"Baggins\" }",//
+				MediaType.APPLICATION_JSON);
+
+		Link bilboLink = assertHasLinkWithRel("self", bilbo);
+
+		assertThat((String) JsonPath.read(bilbo.getContentAsString(), "$.firstName"),
+				equalTo("Bilbo"));
+		assertThat((String) JsonPath.read(bilbo.getContentAsString(), "$.lastName"),
+				equalTo("Baggins"));
+
+		MockHttpServletResponse frodo = patchAndGet(bilboLink,//
+				"{ \"firstName\" : \"Frodo\" }",//
+				MediaType.APPLICATION_JSON);
+
+		assertThat((String) JsonPath.read(frodo.getContentAsString(), "$.firstName"),
+				equalTo("Frodo"));
+		assertThat((String) JsonPath.read(frodo.getContentAsString(), "$.lastName"),
+				equalTo("Baggins"));
+	}
+
+
 	@Test
 	public void listsSiblingsWithContentCorrectly() throws Exception {