Validation control

Parse xsi:nil sensitively

Skip validation process for empty text

As described in before sub section, you can get the ValueElement object, which can accept empty text, by "setNillable(true)". But it only allows the elements with xsi:nil="true" attribute to be empty.

Acceptable document:

    <int xsi:nil="true"/>

Unacceptable document:

    <int/>

In fact, it depends on type specific validation whether empty text is acceptable or not.

For example, "StringElement" can accept empty text even though it does not have xsi:nil="true" attribute, because "empty text" is also "string". On the other hand, "DateTimeElement" (and many of classes derived from ValueElement) rejects it because "empty text" does not satisfy "date time" restriction.

So, ValueElement now provides "setIgnoreEmpty(true)" method to specify skipping validation process for empty text. For example:

IntElement element = new IntElement(parent, null, "int");
element.setIgnoreEmpty(true);

Above element can accept "<int/>", even though it does not have xsi:nil="true" attribute.

Delay validation process

ValueElement validates described text as soon as receiving "endElement" SAX event (= at the end of corresponded tag). But such immediateness prevents you from continuing document processing without invalid elements. For example:

<entry name="1">
  <int>abcd</int> <!-- invalid "int" -->
  <date>2006-12-31</date>
</entry>
<entry name="2">
  <int>1234</int>
  <date>2006/12/31</date> <!-- invalid "date" -->
</entry>
<entry name="3">
  <int>1234</int>
  <date>2006-12-31</date>
</entry>

"Immediate validation" throws SAXException at the end of int element of name="1" entry, and such throwing does not allow continuation of document parsing. So it is not good for the situation that you want to process valid entries(name="3", in this case) and to log information about other invalid entries.

You can prevent ValueElement from "validating described text at the end of element" by "setDelayed(true)" invocation.

This invocation delays validation process until explicit "validate()" invocation. So you can ignore(or detect) invalid "<entry>" by code shown below.

CompositeElement entry = 
    new CompositeElement(parent, null, "entry");

final
IntElement intElement = 
    new IntElement(entry, null, "int");
intElement.setDelayed(true);
entry.addMustItem(intElement);

final
DateElement dateElement = 
    new DateElement(entry, null, "date", ....);
dateElement.setDelayed(true);
entry.addMustItem(dateElement);

entry.addNotification(new Notification(){
    public void elementStarted(Element element,
                               ParseContext context,
                               Attributes attributes)
    { /* nop */ }

    public void elementEnded(Element element,
                             ParseContext context)
    {
        try{
            Integer intValue = 
            (Integer)(intElement.validate(context, false));
            // above invocates "delayed" validation

            Date dateValue =
            (Date)(dateElement.validate(context, false));
            // above invocates "delayed" validation

            /* your custom processing is placed here ..... */
        }
        catch(Exception e){
            /* log validation error detail */
        }
    }
});

By the way, using "addOptionalItem()" instead of "addMustItem()" allows you to ignore(or detect) incomplete "<entry>".