Re: [jibx-users] XML union support in Xsd2Jibx tool

[Dennis Sosnoski]

I personally think unions are an especially ugly kludge in schema, but 
understand that since schema defines them people need to work with them. 
The best way I can suggest for handling them is by creating a class that 
has members matching the components of the union along with some form of 
mode field to say which type of component is used by this particular 
instance, then use a custom serializer/deserializer for converting to 
and from instances of this class. This gets ugly - the deserializer code 
first has to look at the data provided to determine the actual 
deserializer to be used, and then call that type-specific deserializer 
and store the result in the appropriate member field, along with setting 
the mode field value to match.

So for this very simple union:
<simpleType name="volumeControl">
 <union>
   <simpleType>
     <restriction base="int">
       <minInclusive value="0"/>
       <maxInclusive value="10"/>
     </restriction>
   </simpleType>
   <simpleType>
     <restriction base="token">
       <enumeration value="quiet"/>
       <enumeration value="loud"/>
       <enumeration value="really loud"/>
     </restriction>
   </simpleType>
 </union>
</simpleType>
you'd need a structure like:
public class VolumeControlType
{
   private int m_type;  // 0 for int, 1 for token
   private int m_intValue;
   private String m_tokenValue;
  
   public static VolumeControlType deserialize(String value) {
       if (value.size() == 0 || !Character.isDigit(value.charAt(0))) {
           m_type = 1;
           m_tokenValue = value;  // except really should check the 
actual values
       } else {
           m_type = 0;
           m_intValue = ...deserializerInt(value);
       }
   }
   // plus getter/setters, etc.
}

Generating this would be a mess, especially if you try to do it with the 
existing Xsd2Jibx code. My current plans with Xsd2Jibx are to release 
the current CVS version as beta 1 along with JiBX RC0 next week, then 
ignore it. It'd be great if someone could come up with a better 
alternative; I've discussed some options with Cameron, the original 
author of the current code, and have also suggested on this list the 
possibility of taking Castor's code generation and modifying it to leave 
out the Castor-specific stuff while also generating JiBX bindings.

 - Dennis
Dave Lucek wrote:
Hi,
  Does anyone know where in the Xsd2Jibx source code where I should 
look in order to add support for

XML unions?  Or, how can I get this tool to work with XML unions?
 

Thanks
 

  

 

 


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