[castor-user] Marshalling optional attributes?

[Jeff Crump]

Hello,

I'm having trouble with optional (i.e., required=false) attributes in my
input XML.  My Java object looks like this:

class MyElement {
  public Integer val = null;
  public void setVal(int n) { val = new Integer(n); }
  public Integer getVal() return val;
}

The mapping file defines the 'val' field as required=false:

<field name="val" type="int" required="false">
   <bind-xml name="val" node="attribute">
</field>

With an input document like this:

<MyElement/>

the unmarshalling of this is working fine -- if 'val' is not provided in the
input, the setter method does not get called.

My problem is on the marshalling side.  When I re-marshall this object into
XML, the output contains a 'val' attribute set to 0:

<MyElement val="0"/>

How can I tell the marshaller to not create this attribute?  I'd like the
output to be semantically the same as the input, and with this behavior, it
isn't.

Thanks,

Jeff