#750 Documentation update for @Named

core-common/src/main/java/org/mapstruct/Named.java

@@ -35,6 +35,53 @@ import java.lang.annotation.Target;
  * <li>{@link MapMapping#valueQualifiedByName() }</li>
  * </ul>
  *
+ * <p>
+ * Example:
+ *
+ * <pre>
+ * <code>
+ * &#64;Named("TitleTranslator")
+ * public class Titles {
+ *
+ *   &#64;Named("EnglishToGerman")
+ *   public String translateTitleEG(String title) {
+ *       // some mapping logic
+ *   }
+ *
+ *   &#64;Named("GermanToEnglish")
+ *   public String translateTitleGE(String title) {
+ *       // some mapping logic
+ *   }
+ * }
+ *
+ * &#64;Mapper( uses = Titles.class )
+ * public interface MovieMapper {
+ *
+ *    &#64;Mapping( target = "title", qualifiedByName = { "TitleTranslator", "EnglishToGerman" } )
+ *    GermanRelease toGerman( OriginalRelease movies );
+ *
+ * }
+ *
+ * Will generate:
+ *
+ *  private final Titles titles = new Titles();
+ *
+ *  &#64;Override
+ *  public GermanRelease toGerman(OriginalRelease movies) {
+ *      if ( movies == null ) {
+ *          return null;
+ *      }
+ *
+ *      GermanRelease germanRelease = new GermanRelease();
+ *
+ *      germanRelease.setTitle( titles.translateTitleEG( movies.getTitle() ) );
+ *
+ *      return germanRelease;
+ *  }
+ * </code>
+ * </pre>
+ *
+ *
  * @author Sjaak Derksen
  */
 @Target( { ElementType.TYPE, ElementType.METHOD } )

documentation/src/main/asciidoc/mapstruct-reference-guide.asciidoc

@@ -796,7 +796,7 @@ public interface MovieMapper {
 
 }
 ----
-====
+====  
 
 .Custom mapper qualifying the methods it provides
 ====
@@ -829,6 +829,50 @@ A class / method annotated with a qualifier will not qualify anymore for mapping
 The same mechanism is also present on bean mappings: `@BeanMapping#qualifiedBy`: it selects the factory method marked with the indicated qualifier.
 ====
 
+In many occasions, declaring a new annotation to aid the selection process can be too much for what you try to achieve. For those situations, MapStruct has the `@Named` annotation. This annotation is a pre-defined qualifier (annotated with `@Qualifier` itself) and can be used to name a Mapper or, more directly a mapping method by means of its value. The same example above would look like:
+
+.Custom mapper, annotating the methods to qualify by means of `@Named`
+====
+[source, java, linenums]
+[subs="verbatim,attributes"]
+----
+@Named("TitleTranslator")
+public class Titles {
+
+    @Named("EnglishToGerman")
+    public String translateTitleEG(String title) {
+        // some mapping logic
+    }
+
+    @Named("GermanToEnglish")
+    public String translateTitleGE(String title) {
+        // some mapping logic
+    }
+}
+----
+====
+
+.Mapper using named
+====
+[source, java, linenums]
+[subs="verbatim,attributes"]
+----
+@Mapper( uses = Titles.class )
+public interface MovieMapper {
+
+     @Mapping( target = "title", qualifiedByName = { "TitleTranslator", "EnglishToGerman" } )
+     GermanRelease toGerman( OriginalRelease movies );
+
+}
+----
+====  
+
+[WARNING]
+====
+Although the used mechanism is the same, the user has to be a bit more careful. Refactoring the name of a defined qualifier in an IDE will neatly refactor all other occurrences as well. This is obviously not the case for changing a name.
+====
+
+
 [[mapping-collections]]
 == Mapping collections