How can I show/hide a JSF datatable column with ajax?

Question

I have an ajax call that refreshes the following table. Can I have the "Score" column (it is a BigDecimal) hidden if all values are null, otherwise it should display?

<h:dataTable id="theTable" value="#{MyBean.people}" var="person">
  <h:column>
    <f:facet name="header">
      <h:outputText value="Name" />
    </f:facet>
    #{person.name}
  </h:column> 
  <h:column rendered="#{person.score != null}">
    <f:facet name="header">
      <h:outputText value="The Score" />
    </f:facet>
    #{person.score}
  </h:column> 
</h:dataTable>

The current rendered always makes the column NOT render, even when the scores are not null.

Answer 1

There's no "easy" way to do that, you have to look at the complete collection yourself. You could write helper method that checks your list for null values:

public boolean isAllScoresNull() {
    for(Person p : people) {
        if(p.getScore != null) return false;
    }
    return true;
}

and use that via EL in your page:

...
<h:column rendered="#{myBeanController.allScoresNull}">
...

You could also define a TagFunction for that task.