Question

In my JSF application I have two <h:inputText> components. I need to make sure that value is entered in at least one of them. How can I implement such a validator?

I am aware that I can use JavaScript for this, but I’d prefer to do the checks in the server side.

Answer 1

Bind the components to the view, create a <h:inputHidden value="true"> which you put before the components wherein you attach the validator and pass the components as attributes.

E.g.

<h:inputHidden value="true" requiredMessage="Please fill in at least one of those fields">
    <f:validator validatorId="oneOrMoreValidator" />
    <f:attribute name="component1" value="#{component1}" />
    <f:attribute name="component2" value="#{component2}" />
</h:inputHidden>

<h:inputText binding="#{component1}" ... />
<h:inputText binding="#{component2}" ... />

with this @FacesValidator("oneOrMoreValidator") implementation:

@Override
public void validate(FacesContext context, UIComponent component, Object value) throws ValidatorException {
    List<UIInput> inputs = new ArrayList<UIInput>();
    boolean hasValue = false;

    for (int i = 1; i < Integer.MAX_VALUE; i++) {
        UIInput input = (UIInput) component.getAttributes().get("component" + i);

        if (input != null) {
            inputs.add(input);

            if (!hasValue) {
                Object submittedValue = input.getSubmittedValue();
                hasValue |= (submittedValue != null && !String.valueOf(submittedValue).isEmpty());
            }
        } else {
            break;
        }
    }

    if (!inputs.isEmpty() && !hasValue) {
        for (UIInput input : inputs) {
            input.setValid(false);
        }

        String requiredMessage = (String) component.getAttributes().get("requiredMessage");
        throw new ValidatorException(new FacesMessage(FacesMessage.SEVERITY_ERROR, requiredMessage, null));
    }
}