org.apache.juneau.rest.vars.RequestHeaderVar Maven / Gradle / Ivy

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package org.apache.juneau.rest.vars;

import org.apache.juneau.http.response.*;
import org.apache.juneau.rest.*;
import org.apache.juneau.svl.*;

/**
 * Request header variable resolver.
 *
 * 
 * The format for this var is "$RH{key1[,key2...]}".
 *
 * 

 * Used to resolve values returned by {@link RestRequest#getHeader(String)}.
 * 
When multiple keys are used, returns the first non-null/empty value.
 *
 * 
Example:
 * 
 * 	String foo = restRequest.getVarResolver().resolve("$RH{foo}");
 * 	String fooOrBar = restRequest.getVarResolver().resolve("$RH{foo,bar}");
 * 
 *
 * Notes:

 * 	
 * 		This variable resolver requires that a {@link RestRequest} bean be available in the session bean store.
 * 	

 * 		For security reasons, nested and recursive variables are not resolved.
 * 
 *
 * See Also:

 * 	SVL Variables
 * 
 */
public class RequestHeaderVar extends MultipartResolvingVar {

	/** The name of this variable. */
	public static final String NAME = "RH";

	/**
	 * Constructor.
	 */
	public RequestHeaderVar() {
		super(NAME);
	}

	@Override /* Var */
	protected boolean allowNested() {
		return false;
	}

	@Override /* Var */
	protected boolean allowRecurse() {
		return false;
	}

	@Override /* Var */
	public String resolve(VarResolverSession session, String key) {
		return session.getBean(RestRequest.class).orElseThrow(InternalServerError::new).getHeaderParam(key).orElse(null);
	}

	@Override /* Var */
	public boolean canResolve(VarResolverSession session) {
		return session.getBean(RestRequest.class).isPresent();
	}
}