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// ***************************************************************************************************************************
// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
// * distributed with this work for additional information regarding copyright ownership.  The ASF licenses this file        *
// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
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// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
// *                                                                                                                         *
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// ***************************************************************************************************************************
package org.apache.juneau.rest.annotation;

import static java.lang.annotation.ElementType.*;
import static java.lang.annotation.RetentionPolicy.*;

import java.lang.annotation.*;

import org.apache.juneau.rest.*;

/**
 * Annotation that can be applied to a parameter of a {@link RestMethod} annotated method to identify whether or not
 * the request has the specified multipart form POST parameter.
 *
 * 
 * Note that this can be used to detect the existence of a parameter when it's not set to a particular value.
 *
 * 
Example:
 * 
 * 	@RestMethod(name=POST)
 * 	public void doPost(@HasFormData("p1") boolean p1) {
 * 		...
 * 	}
 * 
 *
 * 
 * This is functionally equivalent to the following code...
 * 

 * 	@RestMethod(name=POST)
 * 	public void doPost(RestRequest req) {
 * 		boolean p1 = req.hasFormData("p1");
 * 		...
 * 	}
 * 
 *
 * 
 * The following table shows the behavioral differences between @HasFormData and @FormData...
 * 
 * 	
 * 		
 * 		
 * 		
 * 	
 * 	
 * 		
 * 		
 * 		
 * 	
 * 	
 * 		
 * 		
 * 		
 * 	
 * 	
 * 		
 * 		
 * 		
 * 	
 * 	
 * 		
 * 		
 * 		
 * 	
 * Body content @HasFormData("a") @FormData("a")
a=foo true "foo"
a= true ""
a true null
b=foo false null
 *
 * Important note concerning FORM posts
 *
 * This annotation should not be combined with the {@link Body @Body} annotation or {@link RestRequest#getBody()} method
 * for application/x-www-form-urlencoded POST posts, since it will trigger the underlying servlet API to
 * parse the body content as key-value pairs, resulting in empty content.
 *
 * 
 * The {@link HasQuery @HasQuery} annotation can be used to check for the existing of a URL parameter in the URL string
 * without triggering the servlet to drain the body content.
 */
@Documented
@Target(PARAMETER)
@Retention(RUNTIME)
@Inherited
public @interface HasFormData {

	/**
	 * FORM parameter name.
	 */
	String name() default "";

	/**
	 * A synonym for {@link #name()}.
	 *
	 * 
	 * Allows you to use shortened notation if you're only specifying the name.
	 */
	String value() default "";
}
`Body content`	`@HasFormData("a")`	`@FormData("a")`
`a=foo`	true	"foo"
`a=`	true	""
`a`	true	null
`b=foo`	false	null