Question

I’ve got the following h:commandButton:

<h:commandButton action="#{myBean.myAction}" value="Send">
    <f:param name="myFlag" value="true" />
</h:commandButton>

I want to gain access to myFlag insinde a Validator, that’s attached to another element with f:validator.

Unfortunately, when I want to retrieve the parameter through the FacesContext, I only get null returned.

Is it that the parameters are only sent once all validators have been invoked?

Answer 1

The <f:param> inside <h:commandButton> is only supported since JSF 2.0, but you’re using JSF 1.2. The <f:param> is then only supported in <h:commandLink>.

<h:commandLink action="#{myBean.myAction}" value="Send">
    <f:param name="myFlag" value="true" />
</h:commandLink>

There are alternatives, such as a <h:inputHidden> or <f:setPropertyActionListener> or <f:attribute> or in this case perhaps just plain <input type="hidden"> (the hidden input component and the action listener will only set their value during update model values which is later than validations phase; the attribute tag has better to be set on the component which invokes the validator). As the functional requirement is unclear, it’s not possible to suggest the best alternative.

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Update as per the comments, apparently all you need to know is if the particular button is pressed or not; in that case just give it and the parent form a fixed ID

<h:form id="form">
    <h:commandButton id="send" ...>

this way it will have a fixed request parameter name of form:send and you could check on that in the validator:

if (externalContext.getRequestParameterMap().containsKey("form:send")) {
    // Send button is pressed.
}

You can by the way also check for that in the required validators as follows:

<h:inputText ... required="#{not empty param['form:send']}" />

See also:

• Action dependent requireness