Validate rich:dataTable value size's on form submit

Question

I have a "new item" form that requires a list of dates, with the following components:

• A <rich:calendar> input;
• A <a4j:commandButton> that adds the chosen date to a List<Date> chosenDates in the backing bean;
• A <rich:dataTable> with it's value set to the List<Date> chosenDates attribute;
• A <a4j:commandButton> per dataTable row that removes it's date from theList<Date> chosenDates;

How to validate (JSF's validation phase) the size of the chosenDates list on form submit (creation process)?

RichFaces 4, JSF 2.1 (Mojarra).

Answer 1

I'd advise a cleaner approach with a JSF PhaseListener. The JSF processing will stop skip ahead the other phases if validation fails. Create a PhaseListener that will inspect the size of your list during the validations phase as against during the model update/invoke action phase. Try something like this

1. Create a phase listener for the validations phase

   public class TestPhaseListener implements PhaseListener {
   
      @Override
      public void afterPhase(PhaseEvent event) {
         throw new UnsupportedOperationException("Not supported yet.");
      }
   
      @Override
      public void beforePhase(PhaseEvent event) {
   
         if(event.getPhaseId().equals(PhaseId.PROCESS_VALIDATIONS)){
           FacesContext ctx = event.getFacesContext();
           YourBeanClass theBeanClass = ctx.getApplication().evaluateExpressionGet(ctx, "#{someBean}", YourNeanClass.class); //obtain a reference to the backing bean containing the list
   /*
      inspect the size of the list here and based on that throw the exception below
    */
          throw new ValidatorException(new FacesMessage("Too many dates","Too Many Dates"));
         }
      }
   
       @Override
       public PhaseId getPhaseId() {
          throw new UnsupportedOperationException("Not supported yet.");
       }
    } 
   

2. Register your new listener in the faces_config.xml file

   <lifecycle>
      <phase-listener>your.package.structure.TestPhaseListener</phase-listener>
   </lifecycle>
   

EDIT: Based on your comment, as an alternative, you can hook into the component's lifecycle using the <f:event/> tag and the preValidate or postValidate events (depending on your preference)

1. A listener tag to your component

      <rich:dataTable>
          <f:event type="preValidate" listener="#{yourBean.listener}"/>
      </rich:dataTable>
   

2. Define a listener method in your backing bean to run per your defined event. The method signature must take an argument of type ComponentSystemEvent

       public void preCheck(ComponentSystemEvent evt){
          //You're in your backing bean so you can do pretty much whatever you want. I'd advise you mark the request as validation failed and queue FacesMessages. Obtain a reference to FacesContext and:
   
           facesContext.validationFailed();
   
   
        }