SDO handling of simple types for xs:anyType elements

basti — Wed, 01 Dec 2010 13:23:47 +0000

In the specification of SDO is defined that “xs:anyType”s in xml schema documents are represented in a map of DataObject SDO types. This leads to the problem of assigning simple types like String, Integer and Booleans. By assignment of a simple type to an element of anyType, you receive an ClassCastException at runtime. To solve this issue, it is necessary to wrap the simple types to SDO DataObject’s.

Example would be helpful? No problem :)
Assumed we have the following xml schema:

 version="1.0" encoding="UTF-8"?>
 xmlns:xs="http://www.w3.org/2001/XMLSchema xmlns:catify="http://www.catify.com" targetNamespace="http://www.catify.com"> 
   name="document" type="catify:documentType" />
   name="documentType">
    >
       name="property1" type="xs:string" />
       name="property2" type="xs:anyType" />
    >
  >
>

If we assign a simple java.lang.String value to property1, the result is as expected. But when you try to assign a simple java.lang.String to property2 we run to the implied java.lang.ClassCastException. Remember, SDO treats anyType elements as a map of DataObjects.

String property1Value = "property1Value";
String property2Value = "property2Value";
 
// register xml schema
XSDHelper.INSTANCE.define(getXmlSchema());
 
// create instance of document defined in xml schema
DataObject documentType = DataFactory.INSTANCE.create("http://www.catify.com", "documentType");
 
// set first property -> all is fine
documentType.set("property1", property1Value);
 
// if we try it this way -> we receive a java.lang.ClassCastException
documentType.set("property2", property2Value);

So we have to wrap the simple type (java.lang.String in our example) to a DataObject before assigning it to property2.

// create a wrapper for string types
DataObject property2ValueWrapper = DataFactory.INSTANCE.create(String.class);
 
// set the value
property2ValueWrapper.set("value", property2Value);
 
// assign the string wrapper to property2 of document
documentType.set("property2", property2ValueWrapper);

Lastly we need a mechanism to unwrap the assigned value to work further.

String simpleTypeValue = null;
DataObject property2 = documentType.getDataObject("property2");
if (property2.getType() instanceof SDOWrapperType) {
  simpleTypeValue = (String) property2.get("value");
}

The next step is to implement a utility class that provides a wrap and unwrap method to handle simple types as DataObjects. After the information in this post, it must be easy for you to implement such a class. Have fun!

catify » SDO

SDO handling of simple types for xs:anyType elements