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jsfelmanaged-bean

Evaluate EL expression from bean in JSF page

Is there any way to execute EL expression received from bean in JSF page?

Bean method

public class Bean {

    public String getExpr() {
        return "#{emtpy row.prop ? row.anotherProp : row.prop}";
    }

}

JSF page:

<p:dataTable value="#{bean.items}" var="row">
    <p:column>
        <h:outputText value="#{bean.expr}" />
    </p:column>
</p:dataTable>
Solution

  • Either use JSF Application#evaluateExpressionGet() in getter to programmatically evaluate an EL expression on the current context. This is in this specific case only fishy as you're basically tight-coupling view logic in the controller/model.

    public String getExpr() {
    FacesContext context = FacesContext.getCurrentInstance();
    return context.getApplication().evaluateExpressionGet(context, "#{emtpy row.prop ? row.anotherProp : row.prop}", String.class);
}

    Or use JSTL <c:set> (without scope!) in view to create an alias of an EL expression in the view in case your actual concern is the length of the EL expression.

    <c:set var="expr" value="#{emtpy row.prop ? row.anotherProp : row.prop}" />

<p:dataTable value="#{bean.items}" var="row">
    <p:column>
        <h:outputText value="#{expr}" />
    </p:column>
</p:dataTable>

    Needless to say that JSTL way is way much cleaner.

    See also: