HHH-8854 Resolve any TypeVariables to Class or ParameterizedType when

creating AttributeConverterDefinition

Author: Svein

hibernate-core/src/main/java/org/hibernate/cfg/AttributeConverterDefinition.java

@@ -156,6 +156,7 @@ private ParameterizedType extractAttributeConverterParameterizedType(Type base)
 			types.add( clazz.getGenericSuperclass() );
 			types.addAll( Arrays.asList( clazz.getGenericInterfaces() ) );
 			for ( Type type : types ) {
+				type = resolveType( type, base );
 				if ( ParameterizedType.class.isInstance( type ) ) {
 					final ParameterizedType parameterizedType = (ParameterizedType) type;
 					if ( AttributeConverter.class.equals( parameterizedType.getRawType() ) ) {
@@ -171,6 +172,54 @@ private ParameterizedType extractAttributeConverterParameterizedType(Type base)
 		return null;
 	}
 
+	private static Type resolveType(Type target, Type context) {
+		if ( target instanceof ParameterizedType ) {
+			return resolveParameterizedType( (ParameterizedType) target, context );
+		}
+		else if ( target instanceof TypeVariable ) {
+			return resolveTypeVariable( (TypeVariable) target, (ParameterizedType) context );
+		}
+		return target;
+	}
+
+	private static ParameterizedType resolveParameterizedType(final ParameterizedType parameterizedType, Type context) {
+		Type[] actualTypeArguments = parameterizedType.getActualTypeArguments();
+
+		final Type[] resolvedTypeArguments = new Type[actualTypeArguments.length];
+		for ( int idx = 0; idx < actualTypeArguments.length; idx++ ) {
+			resolvedTypeArguments[idx] = resolveType( actualTypeArguments[idx], context );
+		}
+		return new ParameterizedType() {
+
+			@Override
+			public Type[] getActualTypeArguments() {
+				return resolvedTypeArguments;
+			}
+
+			@Override
+			public Type getRawType() {
+				return parameterizedType.getRawType();
+			}
+
+			@Override
+			public Type getOwnerType() {
+				return parameterizedType.getOwnerType();
+			}
+
+		};
+	}
+
+	private static Type resolveTypeVariable(TypeVariable typeVariable, ParameterizedType context) {
+		Class clazz = extractClass( context.getRawType() );
+		TypeVariable[] typeParameters = clazz.getTypeParameters();
+		for ( int idx = 0; idx < typeParameters.length; idx++ ) {
+			if ( typeVariable.getName().equals( typeParameters[idx].getName() ) ) {
+				return resolveType( context.getActualTypeArguments()[idx], context );
+			}
+		}
+		return typeVariable;
+	}
+
 	public AttributeConverter getAttributeConverter() {
 		return attributeConverter;
 	}

hibernate-core/src/test/java/org/hibernate/test/type/AttributeConverterOnSuperclassTest.java

@@ -2,6 +2,8 @@
 
 import static org.junit.Assert.assertEquals;
 
+import java.util.List;
+
 import javax.persistence.AttributeConverter;
 
 import org.hibernate.cfg.AttributeConverterDefinition;
@@ -11,7 +13,8 @@
 
 /**
  * Test the ability to interpret and understand AttributeConverter impls when the base class does not
- * explicitly implement AttributeConverter but implements it via an interface or superclass.
+ * explicitly implement AttributeConverter but implements it via an interface or superclass. This also
+ * involves resolving any TypeVariables to Class or ParameterizedType.
  * 
  * @author Svein Baardsen
  */
@@ -62,4 +65,38 @@ public void testAttributeConverterOnInterface() {
 		assertEquals( String.class, def.getEntityAttributeType() );
 	}
 
+	public static class NoopAttributeConverter<T> implements AttributeConverter<T, T> {
+
+		@Override
+		public T convertToDatabaseColumn(T attribute) {
+			return attribute;
+		}
+
+		@Override
+		public T convertToEntityAttribute(T dbData) {
+			return dbData;
+		}
+	}
+
+	public static class StringNoopAttributeConverter extends NoopAttributeConverter<String> {
+	}
+
+	@Test
+	public void testTypeVariableAttributeConverterTypeArguments() {
+		AttributeConverterDefinition def = AttributeConverterDefinition.from( StringNoopAttributeConverter.class );
+		assertEquals( String.class, def.getEntityAttributeType() );
+	}
+
+	public static class ListNoopAttributeConverter<T> extends NoopAttributeConverter<List<T>> {
+	}
+
+	public static class StringListNoopAttributeConverter extends ListNoopAttributeConverter<String> {
+	}
+
+	@Test
+	public void testParameterizedTypeWithTypeVariableAttributeConverterTypeArguments() {
+		AttributeConverterDefinition def = AttributeConverterDefinition.from( StringListNoopAttributeConverter.class );
+		assertEquals( List.class, def.getEntityAttributeType() );
+	}
+	
 }