SPR-6709 Handle RequestBodyNotValidException and update reference docs

org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/mvc/method/annotation/support/RequestBodyNotValidException.java

@@ -17,6 +17,7 @@
 package org.springframework.web.servlet.mvc.method.annotation.support;
 
 import org.springframework.validation.Errors;
+import org.springframework.validation.ObjectError;
 import org.springframework.web.bind.annotation.RequestBody;
 
 /**
@@ -45,4 +46,14 @@ public class RequestBodyNotValidException extends RuntimeException {
 		return errors;
 	}
 
+	@Override
+	public String getMessage() {
+		StringBuilder sb = new StringBuilder("Request body content validation failed: ");
+		sb.append(errors.getErrorCount()).append(" errors");
+		for (ObjectError error : errors.getAllErrors()) {
+			sb.append('\n').append(error);
+		}
+		return sb.toString();
+	}
+	
 }

org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/mvc/support/DefaultHandlerExceptionResolver.java

@@ -16,13 +16,14 @@
 
 package org.springframework.web.servlet.mvc.support;
 
+import java.io.IOException;
 import java.util.List;
+
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-
 import org.springframework.beans.ConversionNotSupportedException;
 import org.springframework.beans.TypeMismatchException;
 import org.springframework.core.Ordered;
@@ -37,6 +38,7 @@ import org.springframework.web.HttpRequestMethodNotSupportedException;
 import org.springframework.web.bind.MissingServletRequestParameterException;
 import org.springframework.web.servlet.ModelAndView;
 import org.springframework.web.servlet.handler.AbstractHandlerExceptionResolver;
+import org.springframework.web.servlet.mvc.method.annotation.support.RequestBodyNotValidException;
 import org.springframework.web.servlet.mvc.multiaction.NoSuchRequestHandlingMethodException;
 
 /**
@@ -116,6 +118,9 @@ public class DefaultHandlerExceptionResolver extends AbstractHandlerExceptionRes
 			else if (ex instanceof HttpMessageNotWritableException) {
 				return handleHttpMessageNotWritable((HttpMessageNotWritableException) ex, request, response, handler);
 			}
+			else if (ex instanceof RequestBodyNotValidException) {
+				return handleRequestBodyNotValidException((RequestBodyNotValidException) ex, request, response, handler);
+			}
 		}
 		catch (Exception handlerException) {
 			logger.warn("Handling of [" + ex.getClass().getName() + "] resulted in Exception", handlerException);
@@ -314,4 +319,20 @@ public class DefaultHandlerExceptionResolver extends AbstractHandlerExceptionRes
 		return new ModelAndView();
 	}
 
+	/**
+	 * Handle the case where the object created from the body of a request has failed validation. The default
+	 * implementation sends an HTTP 500 error along with a message containing the errors.
+	 * @param request current HTTP request
+	 * @param response current HTTP response
+	 * @param handler the executed handler, or <code>null</code> if none chosen
+	 * at the time of the exception (for example, if multipart resolution failed)
+	 * @return a ModelAndView to render, or <code>null</code> if handled directly
+	 * @throws Exception an Exception that should be thrown as result of the servlet request
+	 */
+	protected ModelAndView handleRequestBodyNotValidException(RequestBodyNotValidException ex,
+			HttpServletRequest request, HttpServletResponse response, Object handler) throws IOException {
+ 		response.sendError(HttpServletResponse.SC_BAD_REQUEST, ex.getMessage());
+		return new ModelAndView();
+	}
+
 }

org.springframework.web.servlet/src/test/java/org/springframework/web/servlet/mvc/method/annotation/support/RequestResponseBodyMethodProcessorTests.java

@@ -23,9 +23,9 @@ import static org.easymock.EasyMock.isA;
 import static org.easymock.EasyMock.replay;
 import static org.easymock.EasyMock.reset;
 import static org.easymock.EasyMock.verify;
-import static org.junit.Assert.*;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
@@ -49,7 +49,6 @@ import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.StringHttpMessageConverter;
 import org.springframework.mock.web.MockHttpServletRequest;
 import org.springframework.mock.web.MockHttpServletResponse;
-import org.springframework.validation.DataBinder;
 import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
 import org.springframework.web.HttpMediaTypeNotAcceptableException;
 import org.springframework.web.HttpMediaTypeNotSupportedException;

spring-framework-reference/src/mvc.xml

@@ -1369,9 +1369,18 @@ public void handle(@RequestBody String body, Writer writer) throws IOException {
 <bean id="castorMarshaller" class="org.springframework.oxm.castor.CastorMarshaller"/>
 </programlisting>
 
+        <para>An <classname>@RequestBody</classname> method parameter can be annotated with 
+        <classname>@Valid</classname>, in which case it will validated using the configured
+        <classname>Validator</classname> instance. When using the MVC namespace a JSR-303 
+        validator is configured automatically assuming a JSR-303 implementation is available 
+        on the classpath. If validation fails a <classname>RequestBodyNotValidException</classname>
+        is raised. The exception is handled by the <classname>DefaultHandlerExceptionResolver</classname>
+        and results in a <literal>500</literal> error send back to the client along with
+        a message containing the validation errors.</para>
+
         <note>
           <para> Also see <xref linkend="mvc-annotation-driven"/> for information on 
-          configuring message converters through the MVC namespace.</para>
+          configuring message converters and a validator through the MVC namespace.</para>
         </note>
       </section>