ClassCastException on deserialization

[Olivier Z.]

I have a JSON string like this:
{"sectionIdStats":"","cdArtist":"xyz","length":220,"sectionId":11,"cdTitle":"track #12","comment":"","clipBase":"/3/2/2/1/075596061223-1-5","dates":"","id":{"value":33012},"discNumber":1,"pickflag":"","trackNumber":12,"idValue":33012}

The object I am deserializng this into has the following setters:
    public void setSectionId(int id)
    {
        //...
    }

    public void setSectionId(String id)
    {
              //...
    }

(from past experience it seems that I need both -- not sure why but that's another issue it seems).

When I call JSONObject.fromString()

I get:
com.[snipsnip].musicops.json.JsonUtil$JsonSerializationException: Error in Deserialization of class com.[snipsnip].mgpi2.model.classical.ClassicalTrack for JSONObject: {"sectionIdStats":"","cdArtist":"XYZ","length":220,"sectionId":11,"cdTitle":"track #12","comment":"","clipBase":"/3/2/2/1/075596061223-1-5","dates":"","id":{"value":33012},"discNumber":1,"pickflag":"","trackNumber":12,"idValue":33012} -- java.lang.IllegalArgumentException: Cannot invoke com.[snipsnip].mgpi2.model.classical.ClassicalTrack.setSectionId - java.lang.ClassCastException@bb12
        at com.[snipsnip].musicops.json.JsonUtil.deserialize(JsonUtil.java:299)
        at com.[snipsnip].musicops.json.JsonUtil.deserialize(JsonUtil.java:323)
        at com.[snipsnip].mgpi2.model.classical.ClassicalModelTest.testAssignTrackSection(ClassicalModelTest.java:554)
Caused by: net.sf.json.JSONException: java.lang.IllegalArgumentException: Cannot invoke com.[snipsnip].mgpi2.model.classical.ClassicalTrack.setSectionId - java.lang.ClassCastException@bb12
        at net.sf.json.JSONObject.toBean(JSONObject.java:682)
        at net.sf.json.JSONObject.toBean(JSONObject.java:554)
        at com.[snipsnip].musicops.json.JsonUtil.deserialize(JsonUtil.java:295)
        ... 67 more
Caused by: java.lang.IllegalArgumentException: Cannot invoke com.[snipsnip].mgpi2.model.classical.ClassicalTrack.setSectionId - java.lang.ClassCastException@bb12
        at org.apache.commons.beanutils.PropertyUtilsBean.invokeMethod(PropertyUtilsBean.java:1778)
        at org.apache.commons.beanutils.PropertyUtilsBean.setSimpleProperty(PropertyUtilsBean.java:1759)
        at org.apache.commons.beanutils.PropertyUtilsBean.setNestedProperty(PropertyUtilsBean.java:1648)
        at org.apache.commons.beanutils.PropertyUtilsBean.setProperty(PropertyUtilsBean.java:1677)
        at org.apache.commons.beanutils.PropertyUtils.setProperty(PropertyUtils.java:559)
        at net.sf.json.JSONObject.setProperty(JSONObject.java:781)
        at net.sf.json.JSONObject.setProperty(JSONObject.java:761)
        at net.sf.json.JSONObject.toBean(JSONObject.java:638)
        ... 69 more

Besides the "why is this happening", is there a way to gather more information on which Class it was trying to cast into what?

Thanks.

[aalmiray]

It looks like you have a property with two setters, the PropertyDescriptor will try its best to determine which is the correct pair of methods for read/write, which I think will be the ones that match the return type with the set type (I'm assuming the return type of sectionId is int). Following that train of thought I created a bean with two properties (int,String) which will have their appropriate setter/getter and an extra setter with another type, so far the tests are green with the latest version from cvs. So either there was a bug that has been corrected or I misunderstood your problem. I'm attaching the code for your perusal.

public class Bean {
   private int integer;
   private String string;

   public int getInteger() {return integer;}
   public String getString() {return string;}
   public void setInteger( int integer ) {this.integer = integer;}
   public void setInteger( String integer )
   {this.integer = new Integer( integer ).intValue();}
   public void setString( int string )
   {this.string = String.valueOf( string );}
   public void setString( String string )
   {this.string = string;}
}

import junit.framework.TestCase;
import net.sf.json.JSONObject;

public class TestBean extends TestCase {
   public void testBean_from_json1() {
      JSONObject json = JSONObject.fromObject( "{'integer':11,'string':12}" );
      Bean b = (Bean) JSONObject.toBean( json, Bean.class );
      assertBean( b );
   }

   public void testBean_from_json2() {
      JSONObject json = JSONObject.fromObject( "{'integer':'11','string':'12'}" );
      Bean b = (Bean) JSONObject.toBean( json, Bean.class );
      assertBean( b );
   }

   public void testBean_with_integers() {
      Bean bean = new Bean();
      bean.setInteger( 11 );
      bean.setString( 12 );
      JSONObject json = JSONObject.fromObject( bean );
      Bean b = (Bean) JSONObject.toBean( json, Bean.class );
      assertBean( b );
   }

   public void testBean_with_strings() {
      Bean bean = new Bean();
      bean.setInteger( "11" );
      bean.setString( "12" );
      JSONObject json = JSONObject.fromObject( bean );
      Bean b = (Bean) JSONObject.toBean( json, Bean.class );
      assertBean( b );
   }

   private void assertBean( Bean b ) {
      assertEquals( 11, b.getInteger() );
      assertEquals( "12", b.getString() );
   }
}

[Olivier Z.]

thanks for the reply. Your test case matches my situation except for the fact that the sectionId which figures as an int in the Json string is actually a class itself with setters. So maybe the introspection doesn't go 'deep enough' or as you said there was a bug that has been fixed. I tried the 2.02a but found some backward compatibility problems so I didn't pursue it.

However, the best thing would be for the ClassCastException message to be more explicit so I can determine what type it is trying (I assume it is 'int' but I cannot be sure) and which method(s) it is trying. Is it possible to turn o some verbose mode that would indicate all this?

Thanks.

[aalmiray]

Hmmm can you send a sample of your code to get more insight? it seems like PropetyUtils catches an IllegalArgumentException and throws a ClassCastException, which is later wrapped in a JSONException, meaning that perhaps there may be an opportunity to know more about the error.

[Olivier Z.]

can I reach you by email? That'll be easier if we start exchanging code. I sent you an email through your sourceforge account, or you can do the same through my sourceforge account.