Problems with conditionals in JSF

Question

I have the code bellow:

<c:set var="show" value="#{cartBean.itemsAdded}" />

<c:if test="${show}">
    <h:form id="test1">
        <h:commandLink action="#{cartBean.foo}">this doesn't work</h:commandLink>           
    </h:form>
</c:if>

<h:form id="test2">
    <h:commandLink action="#{cartBean.foo}">this works!</h:commandLink>         
</h:form>

When show=false, show only the second link. And it works. I can reach server (I'm using debug to see this).

When show=true, both links appears. But ONLY second link works. The link inside conditional doesn't trigger the action in server.

Someone, can, please, help me?

Note: the same thing happens when I use a4j:outputPanel rendered="#{show}"

Answer 1

During processing of the form submit, JSF will re-evaluate whether the command button/link is been rendered. If it is not rendered, then it will simply skip the action.

You need to ensure that the expression #{cartBean.itemsAdded} returns true as well when the form submit is been processed by JSF. An easy test is to put the bean in the session scope (and I assume that the isItemsAdded() is a pure getter, i.e. it contains only return itemsAdded;).

If that did fix the problem and you'd like to keep the bean in the request scope, then add a <a4j:keepAlive> to retain the bean properties in the subsequent request.

<a4j:keepAlive beanName="#{cartBean}" />

See also:

• Commandlink is not being invoked

---

Unrelated to the concrete problem, you should prefer JSF tags/attributes over JSTL ones as much as possible. In this particular case, you should get rid of both JSTL <c:> tags and use the JSF-provided rendered attribute instead:

<h:form id="test1" rendered="#{cartBean.itemsAdded}">
    <h:commandLink action="#{cartBean.foo}">this doesn't work</h:commandLink>           
</h:form>

Answer 2

WORKARROUND:

I don't want to use sessionScope, because of the danger of use this in a huge system (my case). I don't like to use keepAlive neighter, because I'm in a clutered server and many attributes are not serializable.

Anyway, I've found this workarround:

1. Send a parameter in request (like show=true)
2. Change the check method, adding a OR in return to see this new parameter.

---

MANAGED BEAN:

Before:

public boolean itemsAdded() {
    return foo; // my initial check
}

After:

public HttpServletRequest getRequest() {
        return (HttpServletRequest) FacesContext.getCurrentInstance().getExternalContext().getRequest();
}

public boolean itemsAdded() {
    return foo || getRequest().getParameter("show") != null;
}

---

XHTML:

Before:

<c:set var="show" value="#{cartBean.itemsAdded}" />
<c:if test="${show}">
    <h:form id="test1">
        <h:commandLink action="#{cartBean.foo}">link</h:commandLink>           
    </h:form>
</c:if>

After:

<c:set var="show" value="#{cartBean.itemsAdded}" />
<c:if test="${show}">
    <h:form id="test1">
       <h:commandLink action="#{cartBean.foo}">link
          <f:param name="show" value="true"/>
       </h:commandLink> 
    </h:form>
</c:if>

Answer 3

IMPROVED (and tiny) WORKARROUND:

Change only XHTML:

Before:

<c:if test="#{cartBean.itemsAdded}">
    <h:form id="test1">
        <h:commandLink action="#{cartBean.foo}">link</h:commandLink>           
    </h:form>
</c:if>

After:

<c:if test="#{cartBean.itemsAdded || params['show']}">
    <h:form id="test1">
       <h:commandLink action="#{cartBean.foo}">link
          <f:param name="show" value="true"/>
       </h:commandLink> 
    </h:form>
</c:if>