001    // Copyright May 16, 2006 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    package org.apache.tapestry.dojo;
015    
016    import java.text.ParseException;
017    
018    import org.apache.hivemind.ApplicationRuntimeException;
019    import org.apache.tapestry.IBinding;
020    import org.apache.tapestry.IComponent;
021    import org.apache.tapestry.json.JSONObject;
022    
023    /**
024     * @author andyhot
025     * @since 4.1
026     */
027    public final class DojoUtils
028    {
029        /* defeat instantiation */
030        private DojoUtils() { }
031        
032        /**
033         * Converts a parameter of an {@link IComponent} to an instance of {@link JSONObject}.
034         * 
035         * @param component
036         * @param parameterName
037         * @return The parameter parsed into a json structure.
038         */
039        public static JSONObject parseJSONParameter(IComponent component, String parameterName)
040        {
041            IBinding binding = component.getBinding(parameterName);
042            if (binding == null || binding.getObject() == null)
043                return new JSONObject();
044            
045            try
046            {
047                return new JSONObject((String) binding.getObject(String.class));
048            }
049            catch (ParseException ex)
050            {
051                throw new ApplicationRuntimeException( DojoMessages.mustUseValidJsonInParameter(parameterName), 
052                        binding.getLocation() , ex);
053            }
054        }
055    }