001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
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006// *                                                                                                                         *
007// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
008// *                                                                                                                         *
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011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.rest.converters;
014
015import javax.servlet.http.*;
016
017import org.apache.juneau.*;
018import org.apache.juneau.rest.*;
019import org.apache.juneau.transform.*;
020import org.apache.juneau.utils.*;
021
022/**
023 * Converter for enabling of {@link PojoRest} support on response objects returned by a <code>@RestMethod</code> method.
024 * 
025 * <p>
026 * When enabled, objects in a POJO tree returned by the REST method can be addressed through additional URL path
027 * information.
028 * 
029 * <p class='bcode'>
030 *    <jc>// Resource method on resource "http://localhost:8080/sample/addressBook"</jc>
031 *    <ja>@RestMethod</ja>(name=<jsf>GET</jsf>, converters=Traversable.<jk>class</jk>)
032 *    <jk>public void</jk> doGet(RestRequest req, RestResponse res) {
033 *       <jk>return new</jk> AddressBook();
034 *    }
035 * 
036 *    <jc>// Sample usage</jc>
037 *    <jk>public static void</jk> main(String[] args) {
038 *       <jc>// Get the zip code of the 2nd address of the first person in the address book.</jc>
039 *       RestCall r = <jk>new</jk> RestClient().doGet(<js>"http://localhost:8080/sample/addressBook/0/addresses/1/zip"</js>);
040 *       <jk>int</jk> zip = r.getResponse(Integer.<jk>class</jk>);
041 *    }
042 * </p>
043 * 
044 * <h5 class='section'>See Also:</h5>
045 * <ul>
046 *    <li class='jc'>{@link PojoRest} - Additional information on addressing elements in a POJO tree using URL notation.
047 *    <li class='jf'>{@link RestContext#REST_converters} - Registering converters with REST resources.
048 *    <li class='link'><a class="doclink" href="../../../../../overview-summary.html#juneau-rest-server.Converters">Overview &gt; juneau-rest-server &gt; Converters</a>
049 * </ul>
050 */
051public final class Traversable implements RestConverter {
052
053   @Override /* RestConverter */
054   @SuppressWarnings({"rawtypes", "unchecked"})
055   public Object convert(RestRequest req, Object o) throws RestException {
056      if (o == null)
057         return null;
058      
059      String pathRemainder = req.getPathMatch().getRemainder();
060
061      if (pathRemainder != null) {
062         try {
063            BeanSession bs = req.getBeanSession();
064            PojoSwap swap = bs.getClassMetaForObject(o).getPojoSwap(bs);
065            if (swap != null)
066               o = swap.swap(bs, o);
067            PojoRest p = new PojoRest(o, req.getBody().getReaderParser());
068            o = p.get(pathRemainder);
069         } catch (PojoRestException e) {
070            throw new RestException(e.getStatus(), e);
071         } catch (Exception e) {
072            throw new RestException(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, e);
073         }
074      }
075
076      return o;
077   }
078}