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SPR-6801 @ModelAttribute instantiation refinement. 

Instantiate the model attribute from a URI var or a request param only
if the name matches and there is a registered Converter<String, ?>.
This commit is contained in:
Rossen Stoyanchev 2011-09-27 22:48:12 +00:00
parent 34956d30b3
commit b08c7f6e00
4 changed files with 136 additions and 42 deletions
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101
org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/mvc/method/annotation/support/ServletModelAttributeMethodProcessor.java
View File

@ -22,6 +22,10 @@ import java.util.Map;
import javax.servlet.ServletRequest;
import org.springframework.core.MethodParameter;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.core.convert.converter.Converter;
import org.springframework.util.StringUtils;
import org.springframework.validation.DataBinder;
import org.springframework.web.bind.ServletRequestDataBinder;
import org.springframework.web.bind.WebDataBinder;
@ -36,9 +40,9 @@ import org.springframework.web.servlet.mvc.method.annotation.ServletRequestDataB
* A Servlet-specific {@link ModelAttributeMethodProcessor} that applies data
* binding through a WebDataBinder of type {@link ServletRequestDataBinder}.
*
* <p>Adds a fall-back strategy to instantiate a model attribute from a
* URI template variable combined with type conversion, if the model attribute
* name matches to a URI template variable name.
* <p>Also adds a fall-back strategy to instantiate the model attribute from a
* URI template variable or from a request parameter if the name matches the
* model attribute name and there is an appropriate type conversion strategy.
*
* @author Rossen Stoyanchev
* @since 3.1
@ -56,36 +60,89 @@ public class ServletModelAttributeMethodProcessor extends ModelAttributeMethodPr
}
/**
* Add a fall-back strategy to instantiate the model attribute from a URI
* template variable with type conversion, if the model attribute name
* matches to a URI variable name.
* Instantiate the model attribute from a URI template variable or from a
* request parameter if the name matches to the model attribute name and
* if there is an appropriate type conversion strategy. If none of these
* are true delegate back to the base class.
* @see #createAttributeFromUriValue
*/
@Override
protected Object createAttribute(String attributeName,
MethodParameter parameter,
WebDataBinderFactory binderFactory,
NativeWebRequest request) throws Exception {
Map<String, String> uriVariables = getUriTemplateVariables(request);
if (uriVariables.containsKey(attributeName)) {
DataBinder binder = binderFactory.createBinder(request, null, attributeName);
return binder.convertIfNecessary(uriVariables.get(attributeName), parameter.getParameterType());
protected final Object createAttribute(String attributeName,
MethodParameter parameter,
WebDataBinderFactory binderFactory,
NativeWebRequest request) throws Exception {
String value = getRequestValueForAttribute(attributeName, request);
if (value != null) {
Object attribute = createAttributeFromRequestValue(value, attributeName, parameter, binderFactory, request);
if (attribute != null) {
return attribute;
}
}
return super.createAttribute(attributeName, parameter, binderFactory, request);
}
/**
* Obtain a value from the request that may be used to instantiate the
* model attribute through type conversion from String to the target type.
* <p>The default implementation looks for the attribute name to match
* a URI variable first and then a request parameter.
* @param attributeName the model attribute name
* @param request the current request
* @return the request value to try to convert or {@code null}
*/
protected String getRequestValueForAttribute(String attributeName, NativeWebRequest request) {
Map<String, String> variables = getUriTemplateVariables(request);
if (StringUtils.hasText(variables.get(attributeName))) {
return variables.get(attributeName);
}
else if (StringUtils.hasText(request.getParameter(attributeName))) {
return request.getParameter(attributeName);
}
else {
return null;
}
}
@SuppressWarnings("unchecked")
private Map<String, String> getUriTemplateVariables(NativeWebRequest request) {
Map<String, String> uriTemplateVars =
protected final Map<String, String> getUriTemplateVariables(NativeWebRequest request) {
Map<String, String> variables =
(Map<String, String>) request.getAttribute(
HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, RequestAttributes.SCOPE_REQUEST);
return (uriTemplateVars != null) ? uriTemplateVars : Collections.<String, String>emptyMap();
return (variables != null) ? variables : Collections.<String, String>emptyMap();
}
/**
* Create a model attribute from a String request value (e.g. URI template
* variable, request parameter) using type conversion.
* <p>The default implementation converts only if there a registered
* {@link Converter} that can perform the conversion.
* @param sourceValue the source value to create the model attribute from
* @param attributeName the name of the attribute, never {@code null}
* @param parameter the method parameter
* @param binderFactory for creating WebDataBinder instance
* @param request the current request
* @return the created model attribute, or {@code null}
* @throws Exception
*/
protected Object createAttributeFromRequestValue(String sourceValue,
String attributeName,
MethodParameter parameter,
WebDataBinderFactory binderFactory,
NativeWebRequest request) throws Exception {
DataBinder binder = binderFactory.createBinder(request, null, attributeName);
ConversionService conversionService = binder.getConversionService();
if (conversionService != null) {
TypeDescriptor source = TypeDescriptor.valueOf(String.class);
TypeDescriptor target = new TypeDescriptor(parameter);
if (conversionService.canConvert(source, target)) {
return binder.convertIfNecessary(sourceValue, parameter.getParameterType(), parameter);
}
}
return null;
}
/**
* {@inheritDoc}
* <p>Downcast {@link WebDataBinder} to {@link ServletRequestDataBinder} before binding.

64
org.springframework.web.servlet/src/test/java/org/springframework/web/servlet/mvc/method/annotation/SerlvetModelAttributeMethodProcessorTests.java
View File

@ -27,8 +27,10 @@ import org.junit.Before;
import org.junit.Test;
import org.springframework.beans.TestBean;
import org.springframework.core.MethodParameter;
import org.springframework.core.convert.support.DefaultConversionService;
import org.springframework.mock.web.MockHttpServletRequest;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.support.ConfigurableWebBindingInitializer;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.context.request.ServletWebRequest;
@ -60,44 +62,72 @@ public class SerlvetModelAttributeMethodProcessorTests {
@Before
public void setUp() throws Exception {
processor = new ServletModelAttributeMethodProcessor(false);
this.processor = new ServletModelAttributeMethodProcessor(false);
Method method = getClass().getDeclaredMethod("modelAttribute",
TestBean.class, TestBeanWithoutStringConstructor.class);
testBeanModelAttr = new MethodParameter(method, 0);
testBeanWithoutStringConstructorModelAttr = new MethodParameter(method, 1);
this.testBeanModelAttr = new MethodParameter(method, 0);
this.testBeanWithoutStringConstructorModelAttr = new MethodParameter(method, 1);
binderFactory = new ServletRequestDataBinderFactory(null, null);
mavContainer = new ModelAndViewContainer();
ConfigurableWebBindingInitializer initializer = new ConfigurableWebBindingInitializer();
initializer.setConversionService(new DefaultConversionService());
request = new MockHttpServletRequest();
webRequest = new ServletWebRequest(request);
this.binderFactory = new ServletRequestDataBinderFactory(null, initializer );
this.mavContainer = new ModelAndViewContainer();
this.request = new MockHttpServletRequest();
this.webRequest = new ServletWebRequest(request);
}
@Test
public void createAttributeViaPathVariable() throws Exception {
public void createAttributeUriTemplateVar() throws Exception {
Map<String, String> uriTemplateVars = new HashMap<String, String>();
uriTemplateVars.put("testBean1", "pathy");
request.setAttribute(HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, uriTemplateVars);
uriTemplateVars.put("testBean1", "Patty");
this.request.setAttribute(HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, uriTemplateVars);
// Type conversion from "pathy" to TestBean via TestBean(String) constructor
// Type conversion from "Patty" to TestBean via TestBean(String) constructor
TestBean testBean =
(TestBean) processor.resolveArgument(testBeanModelAttr, mavContainer, webRequest, binderFactory);
(TestBean) this.processor.resolveArgument(
this.testBeanModelAttr, this.mavContainer, this.webRequest, this.binderFactory);
assertEquals("pathy", testBean.getName());
assertEquals("Patty", testBean.getName());
}
@Test
public void createAttributeAfterPathVariableConversionError() throws Exception {
public void createAttributeUriTemplateVarCannotConvert() throws Exception {
Map<String, String> uriTemplateVars = new HashMap<String, String>();
uriTemplateVars.put("testBean1", "pathy");
uriTemplateVars.put("testBean2", "Patty");
request.setAttribute(HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, uriTemplateVars);
TestBeanWithoutStringConstructor testBean =
(TestBeanWithoutStringConstructor) processor.resolveArgument(
testBeanWithoutStringConstructorModelAttr, mavContainer, webRequest, binderFactory);
(TestBeanWithoutStringConstructor) this.processor.resolveArgument(
this.testBeanWithoutStringConstructorModelAttr, this.mavContainer, this.webRequest, this.binderFactory);
assertNotNull(testBean);
}
@Test
public void createAttributeRequestParameter() throws Exception {
this.request.addParameter("testBean1", "Patty");
// Type conversion from "Patty" to TestBean via TestBean(String) constructor
TestBean testBean =
(TestBean) this.processor.resolveArgument(
this.testBeanModelAttr, this.mavContainer, this.webRequest, this.binderFactory);
assertEquals("Patty", testBean.getName());
}
@Test
public void createAttributeRequestParameterCannotConvert() throws Exception {
this.request.addParameter("testBean1", "Patty");
TestBeanWithoutStringConstructor testBean =
(TestBeanWithoutStringConstructor) this.processor.resolveArgument(
this.testBeanWithoutStringConstructorModelAttr, this.mavContainer, this.webRequest, this.binderFactory);
assertNotNull(testBean);
}

8
org.springframework.web/src/test/java/org/springframework/web/method/annotation/InitBinderDataBinderFactoryTests.java
View File

@ -99,6 +99,14 @@ public class InitBinderDataBinderFactoryTests {
assertNull(dataBinder.getDisallowedFields());
}
@Test
public void createBinderNullAttrName() throws Exception {
WebDataBinderFactory factory = createBinderFactory("initBinderWithAttributeName", WebDataBinder.class);
WebDataBinder dataBinder = factory.createBinder(webRequest, null, null);
assertNull(dataBinder.getDisallowedFields());
}
@Test(expected=IllegalStateException.class)
public void returnValueNotExpected() throws Exception {
WebDataBinderFactory factory = createBinderFactory("initBinderReturnValue", WebDataBinder.class);

5
spring-framework-reference/src/mvc.xml
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@ -1607,9 +1607,8 @@ public String save(@ModelAttribute("account") Account account) {
<para>In this example the name of the model attribute (i.e. "account")
matches the name of a URI template variable. If you register
<classname>Converter&lt;String, Account&gt;</classname>
(or <classname>PropertyEditor</classname>) that can turn the
<literal>String</literal>-based account into an <classname>Account</classname>
<classname>Converter&lt;String, Account&gt;</classname> that can turn the
<literal>String</literal> account value into an <classname>Account</classname>
instance, then the above example will work without the need for an
<interfacename>@ModelAttribute</interfacename> method.</para>