org.springframework.web.method.annotation

Class ModelAttributeMethodProcessor

java.lang.Object

org.springframework.web.method.annotation.ModelAttributeMethodProcessor

All Implemented Interfaces:

HandlerMethodArgumentResolver, HandlerMethodReturnValueHandler

Direct Known Subclasses:

ServletModelAttributeMethodProcessor

public class ModelAttributeMethodProcessor
extends Object
implements HandlerMethodArgumentResolver, HandlerMethodReturnValueHandler

Resolves method arguments annotated with @ModelAttribute and handles return values from methods annotated with @ModelAttribute.

Model attributes are obtained from the model or if not found possibly created with a default constructor if it is available. Once created, the attributed is populated with request data via data binding and also validation may be applied if the argument is annotated with @javax.validation.Valid.

When this handler is created with annotationNotRequired=true, any non-simple type argument and return value is regarded as a model attribute with or without the presence of an @ModelAttribute.

Since:

3.1

Author:

Rossen Stoyanchev

Field Summary

Fields

Modifier and Type	Field and Description
protected Log	logger

Constructor Summary

Constructors

Constructor and Description
ModelAttributeMethodProcessor(boolean annotationNotRequired)

Method Summary

Modifier and Type	Method and Description
protected void	bindRequestParameters(WebDataBinder binder, NativeWebRequest request) Extension point to bind the request to the target object.
protected Object	createAttribute(String attributeName, MethodParameter methodParam, WebDataBinderFactory binderFactory, NativeWebRequest request) Extension point to create the model attribute if not found in the model.
void	handleReturnValue(Object returnValue, MethodParameter returnType, ModelAndViewContainer mavContainer, NativeWebRequest webRequest) Add non-null return values to the ModelAndViewContainer.
protected boolean	isBindExceptionRequired(WebDataBinder binder, MethodParameter methodParam) Whether to raise a fatal bind exception on validation errors.
Object	resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) Resolve the argument from the model or if not found instantiate it with its default if it is available.
boolean	supportsParameter(MethodParameter parameter) Returns true if the parameter is annotated with ModelAttribute or in default resolution mode, and also if it is not a simple type.
boolean	supportsReturnType(MethodParameter returnType) Return true if there is a method-level @ModelAttribute or if it is a non-simple type when annotationNotRequired=true.
protected void	validateIfApplicable(WebDataBinder binder, MethodParameter methodParam) Validate the model attribute if applicable.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

logger

protected final Log logger

Constructor Detail

ModelAttributeMethodProcessor

public ModelAttributeMethodProcessor(boolean annotationNotRequired)

Parameters:

annotationNotRequired - if "true", non-simple method arguments and return values are considered model attributes with or without a @ModelAttribute annotation.

Method Detail

supportsParameter

public boolean supportsParameter(MethodParameter parameter)

Returns true if the parameter is annotated with ModelAttribute or in default resolution mode, and also if it is not a simple type.

Specified by:

supportsParameter in interface HandlerMethodArgumentResolver

Parameters:

parameter - the method parameter to check

Returns:

true if this resolver supports the supplied parameter; false otherwise

resolveArgument

public final Object resolveArgument(MethodParameter parameter,
                                    ModelAndViewContainer mavContainer,
                                    NativeWebRequest webRequest,
                                    WebDataBinderFactory binderFactory)
                             throws Exception

Resolve the argument from the model or if not found instantiate it with its default if it is available. The model attribute is then populated with request values via data binding and optionally validated if @java.validation.Valid is present on the argument.

Specified by:

resolveArgument in interface HandlerMethodArgumentResolver

Parameters:

parameter - the method parameter to resolve. This parameter must have previously been passed to HandlerMethodArgumentResolver.supportsParameter(org.springframework.core.MethodParameter) which must have returned true.

mavContainer - the ModelAndViewContainer for the current request

webRequest - the current request

binderFactory - a factory for creating WebDataBinder instances

Returns:

the resolved argument value, or null

Throws:

BindException - if data binding and validation result in an error and the next method parameter is not of type Errors.

Exception - if WebDataBinder initialization fails.

createAttribute

protected Object createAttribute(String attributeName,
                                 MethodParameter methodParam,
                                 WebDataBinderFactory binderFactory,
                                 NativeWebRequest request)
                          throws Exception

Extension point to create the model attribute if not found in the model. The default implementation uses the default constructor.

Parameters:

attributeName - the name of the attribute (never null)

methodParam - the method parameter

binderFactory - for creating WebDataBinder instance

request - the current request

Returns:

the created model attribute (never null)

Throws:

Exception

bindRequestParameters

protected void bindRequestParameters(WebDataBinder binder,
                                     NativeWebRequest request)

Extension point to bind the request to the target object.

Parameters:

binder - the data binder instance to use for the binding

request - the current request

validateIfApplicable

protected void validateIfApplicable(WebDataBinder binder,
                                    MethodParameter methodParam)

Validate the model attribute if applicable.

The default implementation checks for @javax.validation.Valid, Spring's Validated, and custom annotations whose name starts with "Valid".

Parameters:

binder - the DataBinder to be used

methodParam - the method parameter

isBindExceptionRequired

protected boolean isBindExceptionRequired(WebDataBinder binder,
                                          MethodParameter methodParam)

Whether to raise a fatal bind exception on validation errors.

Parameters:

binder - the data binder used to perform data binding

methodParam - the method argument

Returns:

true if the next method argument is not of type Errors

supportsReturnType

public boolean supportsReturnType(MethodParameter returnType)

Return true if there is a method-level @ModelAttribute or if it is a non-simple type when annotationNotRequired=true.

Specified by:

supportsReturnType in interface HandlerMethodReturnValueHandler

Parameters:

returnType - the method return type to check

Returns:

true if this handler supports the supplied return type; false otherwise

handleReturnValue

public void handleReturnValue(Object returnValue,
                              MethodParameter returnType,
                              ModelAndViewContainer mavContainer,
                              NativeWebRequest webRequest)
                       throws Exception

Add non-null return values to the ModelAndViewContainer.

Specified by:

handleReturnValue in interface HandlerMethodReturnValueHandler

Parameters:

returnValue - the value returned from the handler method

returnType - the type of the return value. This type must have previously been passed to HandlerMethodReturnValueHandler.supportsReturnType(org.springframework.core.MethodParameter) which must have returned true.

mavContainer - the ModelAndViewContainer for the current request

webRequest - the current request

Throws:

Exception - if the return value handling results in an error