/*
* Copyright 2002-2016 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.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.web.bind.annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.springframework.core.annotation.AliasFor;
/**
* Annotation to bind a method parameter to a request attribute.
*
* <p>The main motivation is to provide convenient access to request attributes
* from a controller method with an optional/required check and a cast to the
* target method parameter type.
*
* @author Rossen Stoyanchev
* @since 4.3
* @see RequestMapping
* @see SessionAttribute
*/
@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface RequestAttribute {
/**
* Alias for {@link #name}.
*/
@AliasFor("name")
String value() default "";
/**
* The name of the request attribute to bind to.
* <p>The default name is inferred from the method parameter name.
*/
@AliasFor("value")
String name() default "";
/**
* Whether the request attribute is required.
* <p>Defaults to {@code true}, leading to an exception being thrown if
* the attribute is missing. Switch this to {@code false} if you prefer
* a {@code null} or Java 8 {@code java.util.Optional} if the attribute
* doesn't exist.
*/
boolean required() default true;
}