Allow @ProjectedPayload to be used on parameters.

The `@ProjectedPayload` annotation can now be used on parameters. This prepares for the upcoming removal of support for non-annotated projections.

Fixes #3258
Related tickets #2937

Signed-off-by: Chris Bono <[email protected]>

Author: onobc

src/main/java/org/springframework/data/web/ProjectedPayload.java

@@ -15,23 +15,23 @@
  */
 package org.springframework.data.web;
 
-import static java.lang.annotation.ElementType.*;
-import static java.lang.annotation.RetentionPolicy.*;
-
 import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
 /**
  * Annotation to mark projection interfaces that are supposed to be used as projection interface to bind request or
  * response payloads to.
  *
  * @author Oliver Gierke
+ * @author Chris Bono
  * @soundtrack
  * @since 1.13
  */
 @Documented
-@Retention(RUNTIME)
-@Target(TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ ElementType.TYPE, ElementType.PARAMETER })
 public @interface ProjectedPayload {
 }

src/main/java/org/springframework/data/web/ProxyingHandlerMethodArgumentResolver.java

@@ -91,8 +91,8 @@ public boolean supportsParameter(MethodParameter parameter) {
 		}
 
 		// Annotated parameter (excluding multipart @ModelAttribute)
-		if (parameter.hasParameterAnnotation(ProjectedPayload.class) ||
-				(parameter.hasParameterAnnotation(ModelAttribute.class) && !MultipartResolutionDelegate.isMultipartArgument(parameter))) {
+		if ((parameter.hasParameterAnnotation(ProjectedPayload.class) || parameter.hasParameterAnnotation(
+				ModelAttribute.class)) && !MultipartResolutionDelegate.isMultipartArgument(parameter)) {
 			return true;
 		}
 

src/test/java/org/springframework/data/web/ProxyingHandlerMethodArgumentResolverUnitTests.java

@@ -98,6 +98,22 @@ void doesNotSupportAtModelAttributeForMultipartParam() throws Exception {
 		assertThat(resolver.supportsParameter(parameter)).isFalse();
 	}
 
+	@Test // GH-3258
+	void doesSupportAtProjectedPayload() throws Exception {
+
+		var parameter = getParameter("withProjectedPayload", SampleInterface.class);
+
+		assertThat(resolver.supportsParameter(parameter)).isTrue();
+	}
+
+	@Test // GH-3258
+	void doesNotSupportAtProjectedPayloadForMultipartParam() throws Exception {
+
+		var parameter = getParameter("withProjectedPayloadMultipart", MultipartFile.class);
+
+		assertThat(resolver.supportsParameter(parameter)).isFalse();
+	}
+
 	private static MethodParameter getParameter(String methodName, Class<?> parameterType) {
 
 		var method = ReflectionUtils.findMethod(Controller.class, methodName, parameterType);
@@ -124,5 +140,9 @@ interface Controller {
 		void withModelAttribute(@ModelAttribute SampleInterface param);
 
 		void withModelAttributeMultipart(@ModelAttribute MultipartFile file);
+
+		void withProjectedPayload(@ProjectedPayload SampleInterface param);
+
+		void withProjectedPayloadMultipart(@ProjectedPayload MultipartFile file);
 	}
 }