UnsupportedMediaType[Status]Exception reports body type

Issue: SPR-16805

spring-web/src/main/java/org/springframework/web/server/UnsupportedMediaTypeStatusException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,7 @@ package org.springframework.web.server;
 import java.util.Collections;
 import java.util.List;
 
+import org.springframework.core.ResolvableType;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.lang.Nullable;
@@ -37,6 +38,9 @@ public class UnsupportedMediaTypeStatusException extends ResponseStatusException
 
 	private final List<MediaType> supportedMediaTypes;
 
+	@Nullable
+	private final ResolvableType bodyType;
+
 
 	/**
 	 * Constructor for when the specified Content-Type is invalid.
@@ -45,16 +49,32 @@ public class UnsupportedMediaTypeStatusException extends ResponseStatusException
 		super(HttpStatus.UNSUPPORTED_MEDIA_TYPE, reason);
 		this.contentType = null;
 		this.supportedMediaTypes = Collections.emptyList();
+		this.bodyType = null;
 	}
 
 	/**
 	 * Constructor for when the Content-Type can be parsed but is not supported.
 	 */
-	public UnsupportedMediaTypeStatusException(@Nullable MediaType contentType, List<MediaType> supportedMediaTypes) {
-		super(HttpStatus.UNSUPPORTED_MEDIA_TYPE,
-				"Content type '" + (contentType != null ? contentType : "") + "' not supported");
+	public UnsupportedMediaTypeStatusException(@Nullable MediaType contentType, List<MediaType> supportedTypes) {
+		this(contentType, supportedTypes, null);
+	}
+
+	/**
+	 * Constructor for when trying to encode from or decode to a specific Java type.
+	 * @since 5.1
+	 */
+	public UnsupportedMediaTypeStatusException(@Nullable MediaType contentType, List<MediaType> supportedTypes,
+			@Nullable ResolvableType bodyType) {
+
+		super(HttpStatus.UNSUPPORTED_MEDIA_TYPE, initReason(contentType, bodyType));
 		this.contentType = contentType;
-		this.supportedMediaTypes = Collections.unmodifiableList(supportedMediaTypes);
+		this.supportedMediaTypes = Collections.unmodifiableList(supportedTypes);
+		this.bodyType = bodyType;
+	}
+
+	private static String initReason(@Nullable MediaType contentType, @Nullable ResolvableType bodyType) {
+		return "Content type '" + (contentType != null ? contentType : "") + "' not supported" +
+				(bodyType != null ? " for bodyType=" + bodyType.toString() : "");
 	}
 
 
@@ -75,4 +95,16 @@ public class UnsupportedMediaTypeStatusException extends ResponseStatusException
 		return this.supportedMediaTypes;
 	}
 
+	/**
+	 * Return the body type in the context of which this exception was generated.
+	 * This is applicable when the exception was raised as a result trying to
+	 * encode from or decode to a specific Java type.
+	 * @return the body type, or {@code null}
+	 * @since 5.1
+	 */
+	@Nullable
+	public ResolvableType getBodyType() {
+		return this.bodyType;
+	}
+
 }

spring-webflux/src/main/java/org/springframework/web/reactive/function/BodyExtractors.java

@@ -252,7 +252,7 @@ public abstract class BodyExtractors {
 							.flatMap(reader -> reader.getReadableMediaTypes().stream())
 							.collect(Collectors.toList());
 					UnsupportedMediaTypeException error =
-							new UnsupportedMediaTypeException(contentType, supportedMediaTypes);
+							new UnsupportedMediaTypeException(contentType, supportedMediaTypes, elementType);
 					return unsupportedError.apply(error);
 				});
 	}

spring-webflux/src/main/java/org/springframework/web/reactive/function/BodyInserters.java

@@ -327,7 +327,7 @@ public abstract class BodyInserters {
 								.flatMap(reader -> reader.getWritableMediaTypes().stream())
 								.collect(Collectors.toList());
 						UnsupportedMediaTypeException error =
-								new UnsupportedMediaTypeException(contentType, supportedMediaTypes);
+								new UnsupportedMediaTypeException(contentType, supportedMediaTypes, bodyType);
 						return Mono.error(error);
 					});
 		};

spring-webflux/src/main/java/org/springframework/web/reactive/function/UnsupportedMediaTypeException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,7 @@ import java.util.Collections;
 import java.util.List;
 
 import org.springframework.core.NestedRuntimeException;
+import org.springframework.core.ResolvableType;
 import org.springframework.http.MediaType;
 import org.springframework.lang.Nullable;
 
@@ -37,6 +38,9 @@ public class UnsupportedMediaTypeException extends NestedRuntimeException {
 
 	private final List<MediaType> supportedMediaTypes;
 
+	@Nullable
+	private final ResolvableType bodyType;
+
 
 	/**
 	 * Constructor for when the specified Content-Type is invalid.
@@ -45,15 +49,32 @@ public class UnsupportedMediaTypeException extends NestedRuntimeException {
 		super(reason);
 		this.contentType = null;
 		this.supportedMediaTypes = Collections.emptyList();
+		this.bodyType = null;
 	}
 
 	/**
 	 * Constructor for when the Content-Type can be parsed but is not supported.
 	 */
-	public UnsupportedMediaTypeException(@Nullable MediaType contentType, List<MediaType> supportedMediaTypes) {
-		super("Content type '" + (contentType != null ? contentType : "") + "' not supported");
+	public UnsupportedMediaTypeException(@Nullable MediaType contentType, List<MediaType> supportedTypes) {
+		this(contentType, supportedTypes, null);
+	}
+
+	/**
+	 * Constructor for when trying to encode from or decode to a specific Java type.
+	 * @since 5.1
+	 */
+	public UnsupportedMediaTypeException(@Nullable MediaType contentType, List<MediaType> supportedTypes,
+			@Nullable ResolvableType bodyType) {
+
+		super(initReason(contentType, bodyType));
 		this.contentType = contentType;
-		this.supportedMediaTypes = Collections.unmodifiableList(supportedMediaTypes);
+		this.supportedMediaTypes = Collections.unmodifiableList(supportedTypes);
+		this.bodyType = bodyType;
+	}
+
+	private static String initReason(@Nullable MediaType contentType, @Nullable ResolvableType bodyType) {
+		return "Content type '" + (contentType != null ? contentType : "") + "' not supported" +
+				(bodyType != null ? " for bodyType=" + bodyType.toString() : "");
 	}
 
 
@@ -74,4 +95,16 @@ public class UnsupportedMediaTypeException extends NestedRuntimeException {
 		return this.supportedMediaTypes;
 	}
 
+	/**
+	 * Return the body type in the context of which this exception was generated.
+	 * This is applicable when the exception was raised as a result trying to
+	 * encode from or decode to a specific Java type.
+	 * @return the body type, or {@code null}
+	 * @since 5.1
+	 */
+	@Nullable
+	public ResolvableType getBodyType() {
+		return this.bodyType;
+	}
+
 }

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/DefaultServerRequest.java

@@ -62,7 +62,8 @@ class DefaultServerRequest implements ServerRequest {
 
 	private static final Function<UnsupportedMediaTypeException, UnsupportedMediaTypeStatusException> ERROR_MAPPER =
 			ex -> (ex.getContentType() != null ?
-					new UnsupportedMediaTypeStatusException(ex.getContentType(), ex.getSupportedMediaTypes()) :
+					new UnsupportedMediaTypeStatusException(
+							ex.getContentType(), ex.getSupportedMediaTypes(), ex.getBodyType()) :
 					new UnsupportedMediaTypeStatusException(ex.getMessage()));
 
 

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/AbstractMessageReaderArgumentResolver.java

@@ -191,7 +191,7 @@ public abstract class AbstractMessageReaderArgumentResolver extends HandlerMetho
 		if (contentType == null && method != null && SUPPORTED_METHODS.contains(method)) {
 			Flux<DataBuffer> body = request.getBody().doOnNext(o -> {
 				// Body not empty, back to 415..
-				throw new UnsupportedMediaTypeStatusException(mediaType, this.supportedMediaTypes);
+				throw new UnsupportedMediaTypeStatusException(mediaType, this.supportedMediaTypes, elementType);
 			});
 			if (isBodyRequired) {
 				body = body.switchIfEmpty(Mono.error(() -> handleMissingBody(bodyParam)));
@@ -199,7 +199,7 @@ public abstract class AbstractMessageReaderArgumentResolver extends HandlerMetho
 			return (adapter != null ? Mono.just(adapter.fromPublisher(body)) : Mono.from(body));
 		}
 
-		return Mono.error(new UnsupportedMediaTypeStatusException(mediaType, this.supportedMediaTypes));
+		return Mono.error(new UnsupportedMediaTypeStatusException(mediaType, this.supportedMediaTypes, elementType));
 	}
 
 	private Throwable handleReadError(MethodParameter parameter, Throwable ex) {