OmniFaces validateOrder disabling

Question

I'm trying to use validateOrder component to validate two java.util.Date objects. It is similar to showcase example on this link (PrimeFaces example). Everything works perfect, but i have one question:

What if 2nd date field is not required?

In that case i'm getting nullpointer exception, and since validateOrder has "disabled" attribute, i was wondering is it worth/possible enabling/disabling it via ajax every time the 2nd date is inserted/removed. If not, i guess i'll stick to Balus' approach for JSF2.0 cross-field validation that you can read about on this link.

Answer 1

Let the disabled attribute check if the 2nd field is filled in. If it's not filled in, the request parameter value associated with field's client ID will be empty. Use exaclty that to let disabled attribute evaluate to true.

<p:calendar ... binding="#{endDate}" />
...
<o:validateOrder ... disabled="#{empty param[endDate.clientId]}" />

Code is as-is. No additional backing bean property necessary for binding.

See also:

• How does the 'binding' attribute work in JSF? When and how should it be used?