h:dataTable composite component, cc.attrs.var, Ill

问题:

I'm trying to create my own dataTable like the primefaces one. The problem is that cc.attrs.var when used throws a IllegalArgumentException. So I'm wondering how I can have the var attribute like Primefaces.

<cc:interface>
    <cc:attribute name="value"/>
    <cc:attribute name="var"/>
    <cc:attribute name="styleClass"/>
</cc:interface>

<cc:implementation>

    <div>Previous</div>
    <div>Next</div>

    <h:dataTable value="#{cc.attrs.value}" var="#{cc.attrs.var}" styleClass="#{cc.attrs.styleClass}">
        <ui:insert/>
    </h:dataTable>

</cc:implementation>

回答1:

As per the UIData#setValueExpression() javadoc, it's not allowed to have an EL expression in var attribute.

Throws: IllegalArgumentException - if name is one of id, parent, var, or rowIndex

Your best bet is to create a backing component wherein you manually evaluate and set the var attribute of the UIData component bound to <h:dataTable> during the postAddToView event.

<cc:interface componentType="yourTableComposite">
    <cc:attribute name="value" />
    <cc:attribute name="var" />
</cc:interface>
<cc:implementation>
    <f:event type="postAddToView" listener="#{cc.init}" />

    <h:dataTable binding="#{cc.table}" value="#{cc.attrs.value}">
        <cc:insertChildren />
    </h:dataTable>
</cc:implementation>

@FacesComponent("yourTableComposite")
public class YourTableComposite extends UINamingContainer {

    private UIData table;

    public void init() {
        table.setVar((String) getAttributes().get("var"));
    }

    public UIData getTable() {
        return table;
    }

    public void setTable(UIData table) {
        this.table = table;
    }

}

Note that I fixed the <ui:insert> to be <cc:insertChildren>. The <ui:insert> can only be used in <ui:composition>/<ui:decorate>.

See also:

• Initialize a composite component based on the provided attributes
• How does the 'binding' attribute work in JSF? When and how should it be used?