DATAREST-889 - JsonPatchPatchConverter explicitly rejects unknown paths and values.

JsonPatchPatchConverter now explicitly rejects problematic JSON Patch payloads (e.g. incorrect paths, incorrect values) throwing a PatchException.

Original pull request: #227.

spring-data-rest-webmvc/src/main/java/org/springframework/data/rest/webmvc/json/patch/JsonLateObjectEvaluator.java

@@ -42,7 +42,7 @@ class JsonLateObjectEvaluator implements LateObjectEvaluator {
 		try {
 			return mapper.readValue(valueNode.traverse(), type);
 		} catch (Exception e) {
-			return null;
+			throw new PatchException("JSON deserialization exception", e);
 		}
 	}
 }

spring-data-rest-webmvc/src/main/java/org/springframework/data/rest/webmvc/json/patch/JsonPatchPatchConverter.java

@@ -140,7 +140,6 @@ public class JsonPatchPatchConverter implements PatchConverter<JsonNode> {
 		} else if (valueNode.isObject() || (valueNode.isArray())) {
 			return new JsonLateObjectEvaluator(mapper, valueNode);
 		}
-
-		return null;
+		throw new PatchException("Unrecognized valueNode type at path: " + path + ". valueNode: " + valueNode.toString());
 	}
 }

spring-data-rest-webmvc/src/test/java/org/springframework/data/rest/webmvc/json/patch/JsonPatchTests.java

@@ -18,6 +18,7 @@ package org.springframework.data.rest.webmvc.json.patch;
 import static org.junit.Assert.*;
 
 import java.io.IOException;
+import java.math.BigInteger;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -131,6 +132,36 @@ public class JsonPatchTests {
 		assertEquals(Arrays.asList("one", "two", "three"), patchedTodo.getItems());
 	}
 
+	@Test
+	public void patchUnknownType() throws Exception {
+		Todo todo = new Todo();
+		todo.setAmount(BigInteger.ONE);
+
+		try {
+			Patch patch = readJsonPatch("patch-biginteger.json");
+			assertEquals(1, patch.size());
+			assertEquals(new BigInteger("18446744073709551616"), patch.getOperations().get(0).value);
+		} catch (PatchException e) {
+			assertEquals("Unrecognized valueNode type at path: /amount. valueNode: 18446744073709551616", e.getMessage());
+		}
+	}
+
+	@Test
+	public void failureWithInvalidPatchContent() throws Exception {
+		Todo todo = new Todo();
+		todo.setDescription("Description");
+
+		Patch patch = readJsonPatch("patch-failing-with-invalid-content.json");
+		assertEquals(1, patch.size());
+
+		try {
+			Todo patchedTodo = patch.apply(todo, Todo.class);
+			assertEquals("Description", patchedTodo.getDescription());
+		} catch (PatchException e) {
+			assertEquals("JSON deserialization exception", e.getMessage());
+		}
+	}
+
 	private Patch readJsonPatch(String jsonPatchFile) throws IOException, JsonParseException, JsonMappingException {
 
 		ClassPathResource resource = new ClassPathResource(jsonPatchFile, getClass());

spring-data-rest-webmvc/src/test/java/org/springframework/data/rest/webmvc/json/patch/Todo.java

@@ -16,6 +16,7 @@
 
 package org.springframework.data.rest.webmvc.json.patch;
 
+import java.math.BigInteger;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -37,6 +38,7 @@ class Todo {
 	private boolean complete;
 	private TodoType type = new TodoType();
 	private List<String> items = new ArrayList<String>();
+	private BigInteger amount;
 
 	public Todo(Long id, String description, boolean complete) {
 

spring-data-rest-webmvc/src/test/resources/org/springframework/data/rest/webmvc/json/patch/patch-biginteger.json

@@ -0,0 +1,3 @@
+[
+	{"op":"replace", "path":"/amount", "value": 18446744073709551616 }
+]

spring-data-rest-webmvc/src/test/resources/org/springframework/data/rest/webmvc/json/patch/patch-failing-with-invalid-content.json

@@ -0,0 +1,3 @@
+[
+	{"op":"add", "path":"/description", "value": { "content" : "blabla"}}
+]