Tweaked getComponentType() and added getMapValueType() to PersistentProperty.

Changed implementation of getComponentType() to use the TypeInformation instance backing the BasicPersistentProperty.

spring-data-commons-core/src/main/java/org/springframework/data/mapping/BasicPersistentProperty.java

@@ -28,14 +28,14 @@ import org.springframework.data.util.TypeInformation;
 import java.beans.PropertyDescriptor;
 import java.lang.reflect.Field;
 import java.lang.reflect.Modifier;
-import java.lang.reflect.ParameterizedType;
-import java.lang.reflect.Type;
 import java.util.Collection;
-import java.util.List;
 import java.util.Map;
 
 /**
+ * Simple impementation of {@link PersistentProperty}.
+ * 
  * @author Jon Brisbin <jbrisbin@vmware.com>
+ * @author Oliver Gierke
  */
 public class BasicPersistentProperty implements PersistentProperty {
 
@@ -147,7 +147,7 @@ public class BasicPersistentProperty implements PersistentProperty {
 
   @Override
   public boolean isComplexType() {
-    if (isCollection() || isArray()) {
+    if (isCollection() || isArray()) { 
       return !MappingBeanHelper.isSimpleType(getComponentType());
     } else {
       return !MappingBeanHelper.isSimpleType(getType());
@@ -160,19 +160,16 @@ public class BasicPersistentProperty implements PersistentProperty {
   }
 
   @Override
-  public Class<?> getComponentType() {
-    if (isCollection()) {
-      Type genericType = field.getGenericType();
-      if (genericType instanceof ParameterizedType) {
-        Type[] genericTypes = ((ParameterizedType) genericType).getActualTypeArguments();
-        for (Type t : genericTypes) {
-          if (t instanceof Class) {
-            return (Class<?>) t;
-          }
-        }
-      }
-    }
-    return getType().getComponentType();
+  public Class<?> getComponentType() { 
+    return isMap() || isCollection() ? information.getComponentType().getType() : null;
+  }
+  
+  /* (non-Javadoc)
+   * @see org.springframework.data.mapping.model.PersistentProperty#getMapValueType()
+   */
+  @Override
+  public Class<?> getMapValueType() {
+    return isMap() ? information.getMapValueType().getType() : null;
   }
 
   @Override

spring-data-commons-core/src/main/java/org/springframework/data/mapping/model/PersistentProperty.java

@@ -5,10 +5,12 @@ import org.springframework.data.util.TypeInformation;
 
 import java.beans.PropertyDescriptor;
 import java.lang.reflect.Field;
+import java.util.Collection;
+import java.util.Map;
 
 /**
  * @author Graeme Rocher
- * @since 1.0
+ * @author Oliver Gierke
  */
 public interface PersistentProperty {
 
@@ -62,7 +64,20 @@ public interface PersistentProperty {
    */
   boolean isEntity();
 
+  /**
+   * Returns the component type of the type if it is a {@link Collection}. Will return the type of the key if the
+   * property is a {@link Map}.
+   * 
+   * @return the component type, the map's key type or {@literal null} if neither {@link Collection} nor {@link Map}. 
+   */
   Class<?> getComponentType();
+  
+  /**
+   * Returns the type of the values if the property is a {@link Map}.
+   * 
+   * @return the map's value type or {@literal null} if no {@link Map}
+   */
+  Class<?> getMapValueType();
 
   boolean isIdProperty();
 }

spring-data-commons-core/src/test/java/org/springframework/data/util/ClassTypeInformationUnitTests.java

@@ -22,7 +22,10 @@ public class ClassTypeInformationUnitTests {
     TypeInformation discoverer = new ClassTypeInformation(
         ConcreteType.class);
     assertEquals(ConcreteType.class, discoverer.getType());
-    assertEquals(String.class, discoverer.getProperty("content").getType());
+    TypeInformation content = discoverer.getProperty("content");
+    assertEquals(String.class, content.getType());
+    assertNull(content.getComponentType());
+    assertNull(content.getMapValueType());
   }
 
   @Test