Why can't JSF calls method with parameter?

[Pamungkas Timotius]

I have error when trying to execute a simple function. Let's just said I have following method in my backing bean

public void foo(String bar) {
  if (bar.equals("boo")) {
    // do something
  } else {
    return;
  }
}

When I call the method from my JSF, using this code :

<h:commandLink value="#{fooBean.foo(bar)}">
  <h:outputText value="FooBar" />
</h:commandLink>

It displays following error:

foo must be used with a prefix when a default namespace is not specified


Well, I found a link in google. I suppose this will also happen using non-JSF EL in standard JSP page. The problem is how can I fix this in JSF (or JSP) EL?

Does JSF (or JSP) does not support parameterized method?? Why??

[Leonardo Rafaeli]

doesn't support =(

BUT JBOSS SEAM SUPPORTS! exactly like your code ;D

I think you are using a default JSF Implementation, so, in fact myfaces, RI, Rave, ADF , IceFaces and so on really don't support it

there are two ways to you send parameters to your backing bean

your component

<h:commandButton value="Hello" actionListener="#{myBean.myMethod}">
  <f:attribute name="myAttribute" value="hello" />
</h:commandButton>

your backing bean

public class MyBean() {
  public void myMethod( ActionEvent e ) {
    String myAttribute = e.getComponent().getAttributes().get( "myAttrybute" ).toString()
    Log.info( result );
    // Output: hello
  }
}

the second way is using a f:param to send a parameter to your backingbean by request. The main difference of the last way is because this second way can pass parameters when you are calling a action method and not only a actionListener method(I MUST CONFIRM, I DON'T REALLY remember if this affirmation is true hahaha, so you can try and tell us if this way works calling an action :P)

your component:

<h:commandButton value="Hello" actionListener="#{myBean.myMethod}">
  <f:param name="myParam" value="hello" />
</h:commandButton>

your backing bean:

public class MyBean() {
  public void myMethod( ActionEvent e ) {
    String myParam = FacesContext.getCurrentInstance().getExternalContext().getRequestMap().get( "myParam" ).toString();
    Log.info( result );
    // Output: hello
  }
}

did you understand how it works?

I hope so

Leo

[Pamungkas Timotius]

it works..
thanks for your help

[Ian Dunsirn]

Hello,

I tried the first option of Leonardo's response (using attributes) and I got a null pointer exception. Is there any reason this should occur?

[Mark Spritzler]

Originally posted by Ian Dunsirn:
Hello,

I tried the first option of Leonardo's response (using attributes) and I got a null pointer exception. Is there any reason this should occur?

Did you just copy and paste, because in his first one there is a spelling error in the get. Should be "attribute" but is showing "attybute" in the post above.

Mark

[Ian Dunsirn]

No copy and paste at all.

[Bauke Scholtz]

get( "myParam" ).toString();

That's dangerous. What if the param value is null? Just cast the value to String.

You may find this article useful too: http://balusc.blogspot.com/2006/06/communication-in-jsf.html

[Mustafa AYDIN]

f:param works only on h:commandLink and hutputLink:
<h:commandLink value="Hello" actionListener="#{reservationAction.getParam}">
<f:param name="myParam" value="hello" />
</h:commandLink>

public void getParam( ActionEvent e ) {
String myParam = ""+FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("myParam");
System.out.println(myParam);
}

[Bauke Scholtz]

Was it really needed to resurrect an old, dead and already answered topic?