DATACMNS-349 - Opened up SPI in DefaultTypeMapper to allow subclasses to resolve TypeAliases.

Added getAliasFor(TypeInformation) method in DefaultTypeMapper to allow subclasses to resolve TypeAliases.

Author: Thomas Darimont

src/main/java/org/springframework/data/convert/DefaultTypeMapper.java

@@ -35,6 +35,7 @@
  * respectively.
  * 
  * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 public class DefaultTypeMapper<S> implements TypeMapper<S> {
 
@@ -193,12 +194,30 @@ public void writeType(TypeInformation<?> info, S sink) {
 
 		Assert.notNull(info);
 
+		Object alias = getAliasFor(info);
+		if (alias != null) {
+			accessor.writeTypeTo(sink, alias);
+		}
+	}
+
+	/**
+	 * Returns the alias to be used for the given {@link TypeInformation}.
+	 * 
+	 * @param info must not be {@literal null}
+	 * @return the alias for the given {@link TypeInformation} or {@literal null} of none was found or all mappers
+	 *         returned {@literal null}.
+	 */
+	protected final Object getAliasFor(TypeInformation<?> info) {
+
+		Assert.notNull(info);
+
 		for (TypeInformationMapper mapper : mappers) {
 			Object alias = mapper.createAliasFor(info);
 			if (alias != null) {
-				accessor.writeTypeTo(sink, alias);
-				return;
+				return alias;
 			}
 		}
+
+		return null;
 	}
 }

src/test/java/org/springframework/data/convert/DefaultTypeMapperUnitTests.java

@@ -39,15 +39,14 @@
 @RunWith(MockitoJUnitRunner.class)
 public class DefaultTypeMapperUnitTests {
 
+	static final TypeInformation<String> STRING_TYPE_INFO = ClassTypeInformation.from(String.class);
 	static final String STRING = String.class.getName();
 
-	@Mock
-	TypeAliasAccessor<Map<String, String>> accessor;
+	@Mock TypeAliasAccessor<Map<String, String>> accessor;
 
-	@Mock
-	TypeInformationMapper mapper;
+	@Mock TypeInformationMapper mapper;
 
-	TypeMapper<Map<String, String>> typeMapper;
+	DefaultTypeMapper<Map<String, String>> typeMapper;
 	Map<String, String> source;
 
 	@Before
@@ -58,18 +57,30 @@ public void setUp() {
 		this.source = Collections.singletonMap("key", STRING);
 
 		when(accessor.readAliasFrom(source)).thenReturn(STRING);
-		when(mapper.resolveTypeFrom(STRING)).thenReturn((TypeInformation) ClassTypeInformation.from(String.class));
+		when(mapper.resolveTypeFrom(STRING)).thenReturn((TypeInformation) STRING_TYPE_INFO);
 	}
 
 	@Test
 	@SuppressWarnings("rawtypes")
 	public void cachesResolvedTypeInformation() {
 
 		TypeInformation<?> information = typeMapper.readType(source);
-		assertThat(information, is((TypeInformation) ClassTypeInformation.from(String.class)));
+		assertThat(information, is((TypeInformation) STRING_TYPE_INFO));
 		verify(mapper, times(1)).resolveTypeFrom(STRING);
 
 		typeMapper.readType(source);
 		verify(mapper, times(1)).resolveTypeFrom(STRING);
 	}
+
+	/**
+	 * @see DATACMNS-349
+	 */
+	@Test
+	public void returnsTypeAliasForInformation() {
+
+		Object alias = "alias";
+		when(mapper.createAliasFor(STRING_TYPE_INFO)).thenReturn(alias);
+
+		assertThat(this.typeMapper.getAliasFor(STRING_TYPE_INFO), is(alias));
+	}
 }