Java Code Examples for org.springframework.web.bind.WebDataBinder#getBindingResult()

/**
 * Throws MethodArgumentNotValidException if validation fails.
 * @throws HttpMessageNotReadableException if {@link RequestBody#required()}
 * is {@code true} and there is no body content or if there is no suitable
 * converter to read the content with.
 */
@Override
public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
		NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {

	parameter = parameter.nestedIfOptional();
	Object arg = readWithMessageConverters(webRequest, parameter, parameter.getNestedGenericParameterType());
	String name = Conventions.getVariableNameForParameter(parameter);

	if (binderFactory != null) {
		WebDataBinder binder = binderFactory.createBinder(webRequest, arg, name);
		if (arg != null) {
			validateIfApplicable(binder, parameter);
			if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {
				throw new MethodArgumentNotValidException(parameter, binder.getBindingResult());
			}
		}
		if (mavContainer != null) {
			mavContainer.addAttribute(BindingResult.MODEL_KEY_PREFIX + name, binder.getBindingResult());
		}
	}

	return adaptArgumentIfNecessary(arg, parameter);
}
 

protected void validateComponent(WebDataBinder binder, MethodParameter parameter) throws BindException {

        boolean validateParameter = validateParameter(parameter);
        Annotation[] annotations = binder.getTarget().getClass().getAnnotations();
        for (Annotation annot : annotations) {
            if (annot.annotationType().getSimpleName().startsWith("Valid") && validateParameter) {
                Object hints = AnnotationUtils.getValue(annot);
                binder.validate(hints instanceof Object[] ? (Object[]) hints : new Object[]{hints});
            }
        }

        if (binder.getBindingResult().hasErrors()) {
            if (isBindExceptionRequired(binder, parameter)) {
                throw new BindException(binder.getBindingResult());
            }
        }
    }
 

/**
 * 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 {@code @java.validation.Valid} is present on the argument.
 * @throws BindException if data binding and validation result in an error
 * and the next method parameter is not of type {@link Errors}.
 * @throws Exception if WebDataBinder initialization fails.
 */
@Override
public final Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
		NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {

	String name = ModelFactory.getNameForParameter(parameter);
	Object attribute = (mavContainer.containsAttribute(name) ?
			mavContainer.getModel().get(name) : createAttribute(name, parameter, binderFactory, webRequest));

	WebDataBinder binder = binderFactory.createBinder(webRequest, attribute, name);
	if (binder.getTarget() != null) {
		bindRequestParameters(binder, webRequest);
		validateIfApplicable(binder, parameter);
		if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {
			throw new BindException(binder.getBindingResult());
		}
	}

	// Add resolved attribute and BindingResult at the end of the model
	Map<String, Object> bindingResultModel = binder.getBindingResult().getModel();
	mavContainer.removeAttributes(bindingResultModel);
	mavContainer.addAllAttributes(bindingResultModel);

	return binder.convertIfNecessary(binder.getTarget(), parameter.getParameterType(), parameter);
}
 

/**
 * Throws MethodArgumentNotValidException if validation fails.
 * @throws HttpMessageNotReadableException if {@link RequestBody#required()}
 * is {@code true} and there is no body content or if there is no suitable
 * converter to read the content with.
 */
@Override
public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
		NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {

	Object arg = readWithMessageConverters(webRequest, parameter, parameter.getGenericParameterType());
	String name = Conventions.getVariableNameForParameter(parameter);

	WebDataBinder binder = binderFactory.createBinder(webRequest, arg, name);
	if (arg != null) {
		validateIfApplicable(binder, parameter);
		if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {
			throw new MethodArgumentNotValidException(parameter, binder.getBindingResult());
		}
	}
	mavContainer.addAttribute(BindingResult.MODEL_KEY_PREFIX + name, binder.getBindingResult());

	return arg;
}
 

/**
 * Throws MethodArgumentNotValidException if validation fails.
 * @throws HttpMessageNotReadableException if {@link RequestBody#required()}
 * is {@code true} and there is no body content or if there is no suitable
 * converter to read the content with.
 */
@Override
public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
		NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {

	parameter = parameter.nestedIfOptional();
	Object arg = readWithMessageConverters(webRequest, parameter, parameter.getNestedGenericParameterType());
	String name = Conventions.getVariableNameForParameter(parameter);

	WebDataBinder binder = binderFactory.createBinder(webRequest, arg, name);
	if (arg != null) {
		validateIfApplicable(binder, parameter);
		if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {
			throw new MethodArgumentNotValidException(parameter, binder.getBindingResult());
		}
	}
	mavContainer.addAttribute(BindingResult.MODEL_KEY_PREFIX + name, binder.getBindingResult());

	return adaptArgumentIfNecessary(arg, parameter);
}
 

protected void validateComponent(WebDataBinder binder, MethodParameter parameter) throws BindException {

        boolean validateParameter = validateParameter(parameter);
        Annotation[] annotations = binder.getTarget().getClass().getAnnotations();
        for (Annotation annot : annotations) {
            if (annot.annotationType().getSimpleName().startsWith("Valid") && validateParameter) {
                Object hints = AnnotationUtils.getValue(annot);
                binder.validate(hints instanceof Object[] ? (Object[]) hints : new Object[]{hints});
            }
        }

        if (binder.getBindingResult().hasErrors()) {
            if (isBindExceptionRequired(binder, parameter)) {
                throw new BindException(binder.getBindingResult());
            }
        }
    }
 

/**
 * Throws MethodArgumentNotValidException if validation fails.
 * @throws HttpMessageNotReadableException if {@link RequestBody#required()}
 * is {@code true} and there is no body content or if there is no suitable
 * converter to read the content with.
 */
@Override
public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
		NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {

	parameter = parameter.nestedIfOptional();
	Object arg = readWithMessageConverters(webRequest, parameter, parameter.getNestedGenericParameterType());
	String name = Conventions.getVariableNameForParameter(parameter);

	if (binderFactory != null) {
		WebDataBinder binder = binderFactory.createBinder(webRequest, arg, name);
		if (arg != null) {
			validateIfApplicable(binder, parameter);
			if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {
				throw new MethodArgumentNotValidException(parameter, binder.getBindingResult());
			}
		}
		if (mavContainer != null) {
			mavContainer.addAttribute(BindingResult.MODEL_KEY_PREFIX + name, binder.getBindingResult());
		}
	}

	return adaptArgumentIfNecessary(arg, parameter);
}
 

/**
 * 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 {@code @java.validation.Valid} is present on the argument.
 *
 * @throws org.springframework.validation.BindException
 *                   if data binding and validation result in an error
 *                   and the next method parameter is not of type {@link org.springframework.validation.Errors}.
 * @throws Exception if WebDataBinder initialization fails.
 */
public final Object resolveArgument(MethodParameter parameter,
                                    ModelAndViewContainer mavContainer,
                                    NativeWebRequest request,
                                    WebDataBinderFactory binderFactory) throws Exception {
    String name = parameter.getParameterAnnotation(FormModel.class).value();

    Object target = (mavContainer.containsAttribute(name)) ?
            mavContainer.getModel().get(name) : createAttribute(name, parameter, binderFactory, request);

    WebDataBinder binder = binderFactory.createBinder(request, target, name);
    target = binder.getTarget();
    if (target != null) {
        bindRequestParameters(mavContainer, binderFactory, binder, request, parameter);

        validateIfApplicable(binder, parameter);
        if (binder.getBindingResult().hasErrors()) {
            if (isBindExceptionRequired(binder, parameter)) {
                throw new BindException(binder.getBindingResult());
            }
        }
    }

    target = binder.convertIfNecessary(binder.getTarget(), parameter.getParameterType());
    mavContainer.addAttribute(name, target);

    return target;
}
 

/**
 * 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 {@code @java.validation.Valid} is present on the argument.
 * @throws BindException if data binding and validation result in an error
 * and the next method parameter is not of type {@link Errors}.
 * @throws Exception if WebDataBinder initialization fails.
 */
@Override
public final Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
		NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {

	String name = ModelFactory.getNameForParameter(parameter);
	Object attribute = (mavContainer.containsAttribute(name) ? mavContainer.getModel().get(name) :
			createAttribute(name, parameter, binderFactory, webRequest));

	if (!mavContainer.isBindingDisabled(name)) {
		ModelAttribute ann = parameter.getParameterAnnotation(ModelAttribute.class);
		if (ann != null && !ann.binding()) {
			mavContainer.setBindingDisabled(name);
		}
	}

	WebDataBinder binder = binderFactory.createBinder(webRequest, attribute, name);
	if (binder.getTarget() != null) {
		if (!mavContainer.isBindingDisabled(name)) {
			bindRequestParameters(binder, webRequest);
		}
		validateIfApplicable(binder, parameter);
		if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {
			throw new BindException(binder.getBindingResult());
		}
	}

	// Add resolved attribute and BindingResult at the end of the model
	Map<String, Object> bindingResultModel = binder.getBindingResult().getModel();
	mavContainer.removeAttributes(bindingResultModel);
	mavContainer.addAllAttributes(bindingResultModel);

	return binder.convertIfNecessary(binder.getTarget(), parameter.getParameterType(), parameter);
}
 

private void doBind(WebDataBinder binder, NativeWebRequest webRequest, boolean validate,
		Object[] validationHints, boolean failOnErrors) throws Exception {

	doBind(binder, webRequest);
	if (validate) {
		binder.validate(validationHints);
	}
	if (failOnErrors && binder.getBindingResult().hasErrors()) {
		throw new BindException(binder.getBindingResult());
	}
}
 

private void doBind(WebDataBinder binder, NativeWebRequest webRequest, boolean validate,
		Object[] validationHints, boolean failOnErrors) throws Exception {

	doBind(binder, webRequest);
	if (validate) {
		binder.validate(validationHints);
	}
	if (failOnErrors && binder.getBindingResult().hasErrors()) {
		throw new BindException(binder.getBindingResult());
	}
}
 

/**
 * Converts {@link TeapotMapping} to {@link Teapot} domain object. Apply
 * binding on {@link Teapot}.
 */
@Override
public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
        NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {

    /* Read mapping from request */
    TeapotMapping mapping = (TeapotMapping) readWithMessageConverters(
            webRequest, parameter, TeapotMapping.class);
    String name = Conventions.getVariableNameForParameter(parameter);

    /* Convert mapping to domain object */
    Teapot teapot = mapper.fromMapping(mapping);

    WebDataBinder binder = binderFactory
            .createBinder(webRequest, teapot, name);

    if (teapot != null) {
        validateIfApplicable(binder, parameter);
        if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {
            throw new MethodArgumentNotValidException(parameter, binder.getBindingResult());
        }
    }

    mavContainer.addAttribute(BindingResult.MODEL_KEY_PREFIX + name, binder.getBindingResult());

    return teapot;
}
 

/**
 * {@inheritDoc}
 */
@Override
public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
        NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
    String name = UifConstants.DEFAULT_MODEL_NAME;

    Object attribute = null;
    if (mavContainer.containsAttribute(name)) {
        attribute = mavContainer.getModel().get(name);
    }

    WebDataBinder binder = binderFactory.createBinder(webRequest, attribute, name);
    if (binder.getTarget() != null) {
        ServletRequest servletRequest = webRequest.getNativeRequest(ServletRequest.class);
        ServletRequestDataBinder servletBinder = (ServletRequestDataBinder) binder;
        servletBinder.bind(servletRequest);

        if (binder.getBindingResult().hasErrors()) {
            if (isBindExceptionRequired(parameter)) {
                throw new BindException(binder.getBindingResult());
            }
        }
    }

    Map<String, Object> bindingResultModel = binder.getBindingResult().getModel();
    mavContainer.removeAttributes(bindingResultModel);
    mavContainer.addAllAttributes(bindingResultModel);

    return binder.getTarget();
}
 

/**
 * 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 {@code @java.validation.Valid} is present on the argument.
 *
 * @throws org.springframework.validation.BindException
 *                   if data binding and validation result in an error
 *                   and the next method parameter is not of type {@link org.springframework.validation.Errors}.
 * @throws Exception if WebDataBinder initialization fails.
 */
public final Object resolveArgument(MethodParameter parameter,
                                    ModelAndViewContainer mavContainer,
                                    NativeWebRequest request,
                                    WebDataBinderFactory binderFactory) throws Exception {
    String name = parameter.getParameterAnnotation(FormModel.class).value();

    Object target = (mavContainer.containsAttribute(name)) ?
            mavContainer.getModel().get(name) : createAttribute(name, parameter, binderFactory, request);

    WebDataBinder binder = binderFactory.createBinder(request, target, name);
    target = binder.getTarget();
    if (target != null) {
        bindRequestParameters(mavContainer, binderFactory, binder, request, parameter);

        validateIfApplicable(binder, parameter);
        if (binder.getBindingResult().hasErrors()) {
            if (isBindExceptionRequired(binder, parameter)) {
                throw new BindException(binder.getBindingResult());
            }
        }
    }

    target = binder.convertIfNecessary(binder.getTarget(), parameter.getParameterType());
    mavContainer.addAttribute(name, target);

    return target;
}
 

/**
 * 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 {@code @java.validation.Valid} is present on the argument.
 * @throws BindException if data binding and validation result in an error
 * and the next method parameter is not of type {@link Errors}
 * @throws Exception if WebDataBinder initialization fails
 */
@Override
@Nullable
public final Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
		NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {

	Assert.state(mavContainer != null, "ModelAttributeMethodProcessor requires ModelAndViewContainer");
	Assert.state(binderFactory != null, "ModelAttributeMethodProcessor requires WebDataBinderFactory");

	String name = ModelFactory.getNameForParameter(parameter);
	ModelAttribute ann = parameter.getParameterAnnotation(ModelAttribute.class);
	if (ann != null) {
		mavContainer.setBinding(name, ann.binding());
	}

	Object attribute = null;
	BindingResult bindingResult = null;

	if (mavContainer.containsAttribute(name)) {
		attribute = mavContainer.getModel().get(name);
	}
	else {
		// Create attribute instance
		try {
			attribute = createAttribute(name, parameter, binderFactory, webRequest);
		}
		catch (BindException ex) {
			if (isBindExceptionRequired(parameter)) {
				// No BindingResult parameter -> fail with BindException
				throw ex;
			}
			// Otherwise, expose null/empty value and associated BindingResult
			if (parameter.getParameterType() == Optional.class) {
				attribute = Optional.empty();
			}
			bindingResult = ex.getBindingResult();
		}
	}

	if (bindingResult == null) {
		// Bean property binding and validation;
		// skipped in case of binding failure on construction.
		WebDataBinder binder = binderFactory.createBinder(webRequest, attribute, name);
		if (binder.getTarget() != null) {
			if (!mavContainer.isBindingDisabled(name)) {
				bindRequestParameters(binder, webRequest);
			}
			validateIfApplicable(binder, parameter);
			if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {
				throw new BindException(binder.getBindingResult());
			}
		}
		// Value type adaptation, also covering java.util.Optional
		if (!parameter.getParameterType().isInstance(attribute)) {
			attribute = binder.convertIfNecessary(binder.getTarget(), parameter.getParameterType(), parameter);
		}
		bindingResult = binder.getBindingResult();
	}

	// Add resolved attribute and BindingResult at the end of the model
	Map<String, Object> bindingResultModel = bindingResult.getModel();
	mavContainer.removeAttributes(bindingResultModel);
	mavContainer.addAllAttributes(bindingResultModel);

	return attribute;
}
 

@Override
@UsesJava8
public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
		NativeWebRequest request, WebDataBinderFactory binderFactory) throws Exception {

	HttpServletRequest servletRequest = request.getNativeRequest(HttpServletRequest.class);
	assertIsMultipartRequest(servletRequest);

	MultipartHttpServletRequest multipartRequest =
			WebUtils.getNativeRequest(servletRequest, MultipartHttpServletRequest.class);

	Class<?> paramType = parameter.getParameterType();
	boolean optional = paramType.getName().equals("java.util.Optional");
	if (optional) {
		parameter.increaseNestingLevel();
		paramType = parameter.getNestedParameterType();
	}

	String partName = getPartName(parameter);
	Object arg;

	if (MultipartFile.class == paramType) {
		Assert.notNull(multipartRequest, "Expected MultipartHttpServletRequest: is a MultipartResolver configured?");
		arg = multipartRequest.getFile(partName);
	}
	else if (isMultipartFileCollection(parameter)) {
		Assert.notNull(multipartRequest, "Expected MultipartHttpServletRequest: is a MultipartResolver configured?");
		arg = multipartRequest.getFiles(partName);
	}
	else if (isMultipartFileArray(parameter)) {
		Assert.notNull(multipartRequest, "Expected MultipartHttpServletRequest: is a MultipartResolver configured?");
		List<MultipartFile> files = multipartRequest.getFiles(partName);
		arg = files.toArray(new MultipartFile[files.size()]);
	}
	else if ("javax.servlet.http.Part".equals(paramType.getName())) {
		assertIsMultipartRequest(servletRequest);
		arg = servletRequest.getPart(partName);
	}
	else if (isPartCollection(parameter)) {
		assertIsMultipartRequest(servletRequest);
		arg = new ArrayList<Object>(servletRequest.getParts());
	}
	else if (isPartArray(parameter)) {
		assertIsMultipartRequest(servletRequest);
		arg = RequestPartResolver.resolvePart(servletRequest);
	}
	else {
		try {
			HttpInputMessage inputMessage = new RequestPartServletServerHttpRequest(servletRequest, partName);
			arg = readWithMessageConverters(inputMessage, parameter, parameter.getNestedGenericParameterType());
			WebDataBinder binder = binderFactory.createBinder(request, arg, partName);
			if (arg != null) {
				validateIfApplicable(binder, parameter);
				if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {
					throw new MethodArgumentNotValidException(parameter, binder.getBindingResult());
				}
			}
			mavContainer.addAttribute(BindingResult.MODEL_KEY_PREFIX + partName, binder.getBindingResult());
		}
		catch (MissingServletRequestPartException ex) {
			// handled below
			arg = null;
		}
	}

	RequestPart requestPart = parameter.getParameterAnnotation(RequestPart.class);
	boolean isRequired = ((requestPart == null || requestPart.required()) && !optional);

	if (arg == null && isRequired) {
		throw new MissingServletRequestPartException(partName);
	}
	if (optional) {
		arg = Optional.ofNullable(arg);
	}

	return arg;
}
 

@Override
@Nullable
public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
		NativeWebRequest request, @Nullable WebDataBinderFactory binderFactory) throws Exception {

	HttpServletRequest servletRequest = request.getNativeRequest(HttpServletRequest.class);
	Assert.state(servletRequest != null, "No HttpServletRequest");

	RequestPart requestPart = parameter.getParameterAnnotation(RequestPart.class);
	boolean isRequired = ((requestPart == null || requestPart.required()) && !parameter.isOptional());

	String name = getPartName(parameter, requestPart);
	parameter = parameter.nestedIfOptional();
	Object arg = null;

	Object mpArg = MultipartResolutionDelegate.resolveMultipartArgument(name, parameter, servletRequest);
	if (mpArg != MultipartResolutionDelegate.UNRESOLVABLE) {
		arg = mpArg;
	}
	else {
		try {
			HttpInputMessage inputMessage = new RequestPartServletServerHttpRequest(servletRequest, name);
			arg = readWithMessageConverters(inputMessage, parameter, parameter.getNestedGenericParameterType());
			if (binderFactory != null) {
				WebDataBinder binder = binderFactory.createBinder(request, arg, name);
				if (arg != null) {
					validateIfApplicable(binder, parameter);
					if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {
						throw new MethodArgumentNotValidException(parameter, binder.getBindingResult());
					}
				}
				if (mavContainer != null) {
					mavContainer.addAttribute(BindingResult.MODEL_KEY_PREFIX + name, binder.getBindingResult());
				}
			}
		}
		catch (MissingServletRequestPartException | MultipartException ex) {
			if (isRequired) {
				throw ex;
			}
		}
	}

	if (arg == null && isRequired) {
		if (!MultipartResolutionDelegate.isMultipartRequest(servletRequest)) {
			throw new MultipartException("Current request is not a multipart request");
		}
		else {
			throw new MissingServletRequestPartException(name);
		}
	}
	return adaptArgumentIfNecessary(arg, parameter);
}
 

/**
 * 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 {@code @java.validation.Valid} is present on the argument.
 * @throws BindException if data binding and validation result in an error
 * and the next method parameter is not of type {@link Errors}
 * @throws Exception if WebDataBinder initialization fails
 */
@Override
@Nullable
public final Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
		NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {

	Assert.state(mavContainer != null, "ModelAttributeMethodProcessor requires ModelAndViewContainer");
	Assert.state(binderFactory != null, "ModelAttributeMethodProcessor requires WebDataBinderFactory");

	String name = ModelFactory.getNameForParameter(parameter);
	ModelAttribute ann = parameter.getParameterAnnotation(ModelAttribute.class);
	if (ann != null) {
		mavContainer.setBinding(name, ann.binding());
	}

	Object attribute = null;
	BindingResult bindingResult = null;

	if (mavContainer.containsAttribute(name)) {
		attribute = mavContainer.getModel().get(name);
	}
	else {
		// Create attribute instance
		try {
			attribute = createAttribute(name, parameter, binderFactory, webRequest);
		}
		catch (BindException ex) {
			if (isBindExceptionRequired(parameter)) {
				// No BindingResult parameter -> fail with BindException
				throw ex;
			}
			// Otherwise, expose null/empty value and associated BindingResult
			if (parameter.getParameterType() == Optional.class) {
				attribute = Optional.empty();
			}
			bindingResult = ex.getBindingResult();
		}
	}

	if (bindingResult == null) {
		// Bean property binding and validation;
		// skipped in case of binding failure on construction.
		WebDataBinder binder = binderFactory.createBinder(webRequest, attribute, name);
		if (binder.getTarget() != null) {
			if (!mavContainer.isBindingDisabled(name)) {
				bindRequestParameters(binder, webRequest);
			}
			validateIfApplicable(binder, parameter);
			if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {
				throw new BindException(binder.getBindingResult());
			}
		}
		// Value type adaptation, also covering java.util.Optional
		if (!parameter.getParameterType().isInstance(attribute)) {
			attribute = binder.convertIfNecessary(binder.getTarget(), parameter.getParameterType(), parameter);
		}
		bindingResult = binder.getBindingResult();
	}

	// Add resolved attribute and BindingResult at the end of the model
	Map<String, Object> bindingResultModel = bindingResult.getModel();
	mavContainer.removeAttributes(bindingResultModel);
	mavContainer.addAllAttributes(bindingResultModel);

	return attribute;
}
 

@Override
@Nullable
public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
		NativeWebRequest request, @Nullable WebDataBinderFactory binderFactory) throws Exception {

	HttpServletRequest servletRequest = request.getNativeRequest(HttpServletRequest.class);
	Assert.state(servletRequest != null, "No HttpServletRequest");

	RequestPart requestPart = parameter.getParameterAnnotation(RequestPart.class);
	boolean isRequired = ((requestPart == null || requestPart.required()) && !parameter.isOptional());

	String name = getPartName(parameter, requestPart);
	parameter = parameter.nestedIfOptional();
	Object arg = null;

	Object mpArg = MultipartResolutionDelegate.resolveMultipartArgument(name, parameter, servletRequest);
	if (mpArg != MultipartResolutionDelegate.UNRESOLVABLE) {
		arg = mpArg;
	}
	else {
		try {
			HttpInputMessage inputMessage = new RequestPartServletServerHttpRequest(servletRequest, name);
			arg = readWithMessageConverters(inputMessage, parameter, parameter.getNestedGenericParameterType());
			if (binderFactory != null) {
				WebDataBinder binder = binderFactory.createBinder(request, arg, name);
				if (arg != null) {
					validateIfApplicable(binder, parameter);
					if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {
						throw new MethodArgumentNotValidException(parameter, binder.getBindingResult());
					}
				}
				if (mavContainer != null) {
					mavContainer.addAttribute(BindingResult.MODEL_KEY_PREFIX + name, binder.getBindingResult());
				}
			}
		}
		catch (MissingServletRequestPartException | MultipartException ex) {
			if (isRequired) {
				throw ex;
			}
		}
	}

	if (arg == null && isRequired) {
		if (!MultipartResolutionDelegate.isMultipartRequest(servletRequest)) {
			throw new MultipartException("Current request is not a multipart request");
		}
		else {
			throw new MissingServletRequestPartException(name);
		}
	}
	return adaptArgumentIfNecessary(arg, parameter);
}