DATAREDIS-423 - Polishing.

Extend documentation. Reformat JavaDoc. Adjust test method names.

Original pull request: #197.

Author: mp911de

src/main/asciidoc/reference/redis.adoc

@@ -363,9 +363,9 @@ Hash mappers are converters to map objects to a `Map<K, V>` and back. `HashMappe
 
 Multiple implementations are available out of the box:
 
-1. `BeanUtilsHashMapper` using Spring's http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/beans/BeanUtils.html[BeanUtils]
-2. `ObjectHashMapper` using <<redis.repositories.mapping>>
-3. `Jackson2HashMapper` using https://github.com/FasterXML/jackson[FasterXML Jackson].
+1. `BeanUtilsHashMapper` using Spring's http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/beans/BeanUtils.html[BeanUtils].
+2. `ObjectHashMapper` using <<redis.repositories.mapping>>.
+3. <<redis.hashmappers.jackson2,`Jackson2HashMapper`>> using https://github.com/FasterXML/jackson[FasterXML Jackson].
 
 [source,java]
 ----
@@ -397,6 +397,67 @@ public class HashMapping {
 }
 ----
 
+[[redis.hashmappers.jackson2]]
+=== Jackson2HashMapper
+
+`Jackson2HashMapper` provides Redis Hash mapping for domain objects using https://github.com/FasterXML/jackson[FasterXML Jackson].
+`Jackson2HashMapper` can map data map top-level properties as Hash field names and optionally flatten the structure.
+Simple types map to simple values. Complex types (nested objects, collections, maps) are represented as nested JSON.
+
+Flattening creates individual hash entries for all nested properties and resolves complex types into simple types, as far as possible.
+
+[source,java]
+----
+public class Person {
+  String firstname;
+  String lastname;
+  Address address;
+}
+
+public class Address {
+  String city;
+  String country;
+}
+----
+
+.Normal Mapping
+[width="80%",cols="<1,<2",options="header"]
+|====
+|Hash Field
+|Value
+
+|firstname
+|`Jon`
+
+|lastname
+|`Snow`
+
+|address
+|`{ "city" : "Castle Black", "country" : "The North" }`
+|====
+
+.Flat Mapping
+[width="80%",cols="<1,<2",options="header"]
+|====
+|Hash Field
+|Value
+
+|firstname
+|`Jon`
+
+|lastname
+|`Snow`
+
+|address.city
+|`Castle Black`
+
+|address.country
+|`The North`
+|====
+
+NOTE: Flattening requires all property names to not interfere with the JSON path. Using dots or brackets in map keys
+or as property names is not supported using flattening. The resulting hash cannot be mapped back into an Object.
+
 
 :leveloffset: 2
 include::{referenceDir}/redis-messaging.adoc[]

src/main/java/org/springframework/data/redis/hash/Jackson2HashMapper.java

@@ -43,8 +43,13 @@
 
 /**
  * {@link ObjectMapper} based {@link HashMapper} implementation that allows flattening. Given an entity {@code Person}
- * with an {@code Address} like below the flattening will create individual hash entries for all nested properties.
+ * with an {@code Address} like below the flattening will create individual hash entries for all nested properties and
+ * resolve complex types into simple types, as far as possible.
+ * <p>
+ * Flattening requires all property names to not interfere with JSON paths. Using dots or brackets in map keys or as
+ * property names is not supported using flattening. The resulting hash cannot be mapped back into an Object.
  *
+ * <strong>Example</strong>
  * <pre>
  * <code>
  * class Person {
@@ -60,24 +65,25 @@
  * </code>
  * </pre>
  *
- * <pre>
- * <strong>Normal</strong><br />
+ * <strong>Normal</strong>
  * <table>
+ *   <tr><th>Hash field</th><th>Value<th></tr>
  *   <tr><td>firstname</td><td>Jon<td></tr>
  *   <tr><td>lastname</td><td>Snow<td></tr>
- *   <tr><td>address</td><td>{ city : Castle Black, country : The North }<td></tr>
+ *   <tr><td>address</td><td>{ "city" : "Castle Black", "country" : "The North" }<td></tr>
  * </table>
- *
- * <strong>Flat</strong>: <br />
+ * <br />
+ * <strong>Flat</strong>:
  * <table>
+ *   <tr><th>Hash field</th><th>Value<th></tr>
  *   <tr><td>firstname</td><td>Jon<td></tr>
  *   <tr><td>lastname</td><td>Snow<td></tr>
  *   <tr><td>address.city</td><td>Castle Black<td></tr>
  *   <tr><td>address.country</td><td>The North<td></tr>
  * </table>
- * </pre>
  *
  * @author Christoph Strobl
+ * @author Mark Paluch
  * @since 1.8
  */
 public class Jackson2HashMapper implements HashMapper<Object, String, Object> {

src/test/java/org/springframework/data/redis/mapping/Jackson2HashMapperTests.java

@@ -82,7 +82,7 @@ public void setUp() {
 	 * @see DATAREDIS-423
 	 */
 	@Test
-	public void shouldWriteReadHashCorrtectly() {
+	public void shouldWriteReadHashCorrectly() {
 
 		Person jon = new Person("jon", "snow", 19);
 		Address adr = new Address();

src/test/java/org/springframework/data/redis/mapping/Jackson2HashMapperUnitTests.java

@@ -73,7 +73,7 @@ public void shouldMapTypedListOfSimpleType() {
 	 * @see DATAREDIS-423
 	 */
 	@Test
-	public void shouldMapTypledListOfComplexType() {
+	public void shouldMapTypedListOfComplexType() {
 
 		WithList source = new WithList();