Question

I am using JSF 2.0.

I have a h:selectOneMenu on my page which contains a list of values and there is one h:inputText on the same page, whose required should depend on the currently selected value of the h:selectOneMenu. Only a certain set of values should trigger the required check, others not.

This is what I have tried:

<h:inputText ... required="#{(selectedPaymentType.value == 'some value') || (selectedPaymentType.value == 'other value')}" />

In the code above #{selectedPaymentType} is definied in h:selectOneMenu binding.

There are 3 more values like this which should trigger the required attribute to true. This looks kind of clumsy. Are there better ways to do so?

Answer 1

Fant has given a hint in the right direction, that you should be using an enum which has a required property, but it seems that you’re not entirely sure how to properly implement it. Admittedly, Fant’s answer is not elaborate enough. So here’s a more elaborate answer.

Basically, you need to replace all dropdown values by an enum which look like this:

public enum PaymentType {
    FOO("Some label for foo", true),
    BAR("Some label for bar", false),
    BAZ("Some label for baz", true);

    private String label;
    private boolean required;

    private PaymentType(String label, boolean required) {
        this.label = label; 
        this.required = required;
    }

    public String getLabel() { 
        return label;
    }

    public boolean isRequired() {
        return required;
    }
}

And use it as follows

<h:selectOneMenu binding="#{selectedPaymentType}" value="#{bean.selectedPaymentType}">
    <f:selectItems value="#{bean.availablePaymentTypes}" var="paymentType"
        itemValue="#{paymentType}" itemLabel="#{paymentType.label}" />
</h:selectOneMenu>
<h:inputText ... required="#{selectedPaymentType.value.required}" />

with

private PaymentType selectedPaymentType; // +getter+setter

public PaymentType[] getAvailablePaymentTypes() { 
    return PaymentType.values();
}

(or if you’re using OmniFaces, use <o:importConstants>, then you don’t need such a getter for the <f:selectItems>; no, you don’t need a converter in any case, JSF/EL has already builtin conversion for enums)

See, the required attribute is now so much more simplified as it’s already definied in the model associated with the selected value.