ResourceQuery.java

/*
 * JBoss, Home of Professional Open Source
 * Copyright 2008, Red Hat Middleware LLC, and individual contributors
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jboss.seam.resteasy;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.List;

import javax.ws.rs.DefaultValue;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.GenericEntity;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

import org.jboss.resteasy.annotations.providers.jaxb.Wrapped;
import org.jboss.seam.annotations.Create;
import org.jboss.seam.framework.EntityQuery;
import org.jboss.seam.framework.Query;

import static javax.ws.rs.core.Response.Status.UNSUPPORTED_MEDIA_TYPE;
import static javax.ws.rs.core.Response.Status.BAD_REQUEST;

/**
 * This component exposes EntityQuery component as a REST resource responding to
 * HTTP GET request.
 *
 * @author Jozef Hartinger
 * @param <T> entity type
 */
// Empty @Path because it's ignored by second-stage bootstrap if not subclassed or in components.xml
// but we need it as a marker so we'll find components.xml declarations during first stage of bootstrap.
@Path("")
public class ResourceQuery<T> extends AbstractResource<T>
{

   private Query<?, T> entityQuery = null;

   /**
    * Called at component instantiation.
    */
   @Create
   public void create()
   {
      this.entityQuery = getEntityQuery();
      if (entityQuery == null)
      {
         this.entityQuery = createEntityQuery();
      }
   }

   /**
    * Called by RESTEasy to respond for an HTTP GET request. Retrieves a list of
    * entities matching criteria set by query parameters from database and
    * returns it wrapped in Response instance.
    *
    * @param start first entity in the list
    * @param show  maximum size of the list
    * @return representation of a list of database entries
    * @see #getEntityList
    */
   @GET
   @Wrapped
   public Response getResourceList(@QueryParam("start") @DefaultValue("0") int start, @QueryParam("show") @DefaultValue("25") int show)
   {
      MediaType selectedMediaType = selectResponseMediaType();
      if (selectedMediaType == null)
      {
         return Response.status(UNSUPPORTED_MEDIA_TYPE).build();
      }

      if ((start < 0) || (show < 0))
      {
         return Response.status(BAD_REQUEST).build();
      }

      final List<T> result = getEntityList(start, show);
      // create a proper response type
      Type responseType = new ParameterizedType()
      {

         public Type getRawType()
         {
            return result.getClass();
         }

         public Type getOwnerType()
         {
            return null;
         }

         public Type[] getActualTypeArguments()
         {
            return new Type[]{getEntityClass()};
         }
      };
      return Response.ok(new GenericEntity(result, responseType)
      {
      }, selectedMediaType).build();
   }

   /**
    * Retrieve a list of database entities.
    *
    * @param start first entity in the list
    * @param show  maximum size of the list, 0 for unlimited
    * @return list of database entries
    */
   public List<T> getEntityList(int start, int show)
   {
      entityQuery.setFirstResult(start);
      if (show > 0) // set 0 for unlimited
      {
         entityQuery.setMaxResults(show);
      }
      return entityQuery.getResultList();
   }

   /**
    * EntityQuery getter
    *
    * @return EntityQuery instance
    */
   public Query<?, T> getEntityQuery()
   {
      return entityQuery;
   }

   public void setEntityQuery(Query<?, T> query)
   {
      this.entityQuery = query;
   }

   public Query<?, T> createEntityQuery()
   {
      Query<?, T> entityQuery = new EntityQuery<T>();
      entityQuery.setEjbql("select entity from " + getEntityClass().getName() + " entity");
      return entityQuery;
   }
}