Re: [castor-dev] Instantiating extension types using XML mapping

[Naresh Bhatia]

Title: Message

Hope this post did not get lost in the "weekend shuffle" :-). I am really stuck on this problem. Could somebody please comment on whether this is expected to work using XML mapping? It appears that Castor is getting confused by the two classes that map to the same XML element, namely <message>, but in fact are distinguished by their xsi:type attribute.

 

Thanks.

Naresh

-----Original Message-----
From: Naresh Bhatia
Sent: Saturday, February 22, 2003 11:21 PM
To: [EMAIL PROTECTED]
Subject: [castor-dev] Instantiating extension types using XML mapping

I am having trouble instantiating extension types using XML mapping. Castor is not able to instantiate extended types. Here's my schema:

  <xsd:complexType name="MessageType" abstract="true">
  </xsd:complexType>

  <xsd:complexType name="CreateMeetingMessageType">
    <xsd:complexContent>
      <xsd:extension base="MessageType">
        <xsd:sequence>
          <xsd:element name="meeting" type="MeetingType"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  ...

Here's my mapping file:

  <class name="Message">
    <map-to xml="message" ns-uri="my-schema"/>
  </class>

  <class name="CreateMeetingMessage" extends="Message">
    <map-to xml="message" ns-uri="my-schema"/>
    <field name="meeting" type="Meeting">
      <bind-xml name="meeting"/>
    </field>
  </class>
  ...

Here's my XML instance:

<message
  xmlns="my-schema"  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:type="CreateMeetingMessageType">
  <meeting>
    ...
  </meeting>
</message>

When I try to unmarshall this instance using Castor, I get the following exception:

 org.xml.sax.SAXException: unable to instantiate org.framework.message.Message;
     java.lang.InstantiationException: org.framework.message.Message
     at org.exolab.castor.xml.UnmarshalHandler.startElement(Unknown Source)
     at org.exolab.castor.xml.util.DOMEventProducer.process(Unknown Source)
     at org.exolab.castor.xml.util.DOMEventProducer.process(Unknown Source)
     at org.exolab.castor.xml.util.DOMEventProducer.start(Unknown Source)
     at org.exolab.castor.xml.Unmarshaller.unmarshal(Unknown Source)
     at org.exolab.castor.xml.Unmarshaller.unmarshal(Unknown Source)
     at Test.main(Client.java:81)

I would appreciate any ideas to overcome this problem.

Thanks.
Naresh