JSF: Bean method call with parameter

Question

I can't get method calls with parameters to work in JSF 2.0 (MyFaces) and Tomcat 6.

This is how I try it:

<f:selectItems var="item" value="#{bla.someList} itemValue="#{item.value1}" itemLabel="#{item.value2}"> <f:param name="param1" value="0" /> </f:selectItems>

I can't define the method like this, right? And why not?

getSomeList(int a)

So this is what I tried:

getSomeList() {
Integer a = Integer.parseInt(FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("param1")); 
return doSomething(a);
}

And this is what I get:

java.lang.NumberFormatException: null
java.lang.Integer.parseInt(Integer.java:417)

I would be very grateful if someone helped me out. Thanks!

UPDATE: Ah, it worked with #{bla.getSomeList(0)}!

Community · Accepted Answer · 2020-06-20 09:12:55Z

5

I can't define the method like this, right?
getSomeList(int a)

No.

And why not?

Because you're using old Tomcat 6 which doesn't support EL 2.2 where this feature was introduced.

And this is what I get:

java.lang.NumberFormatException: null
java.lang.Integer.parseInt(Integer.java:417)

Because there it is null. The <f:param> works in links/buttons only, not on plain components.

In order to get method calls in EL to work, you need to upgrade to a Servlet 3.0 / EL 2.2 capable container like Tomcat 7, or to replace Tomcat 6's default EL 2.1 implementation by one which supports parameterized method calls. For detail see this answer. Once done that, you can use

<f:selectItems value="#{bla.getSomeList(0)}" ... />

An alternative is to replace List by Map, which can be a custom implementation which does (lazy) loading on get() method.

public Map<String, List<Something>> getSomeMap() {
    return someCustomLazyLoadingMap;
}

with

<f:selectItems value="#{bla.someMap.keyName}" ... />

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Apr 14, 2011 at 16:47

BalusC

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1 Comment

geeehhdaa Over a year ago

Thanks! But it worked with #{bla.getSomeList(0)} instead of #{bla.someList(0)}

aseychell · Accepted Answer · 2011-04-14 16:44:14Z

0

Try using

<f:selectItems var="item" value="#{bla.someList(0)} itemValue="#{item.value1}" itemLabel="#{item.value2}"/>

This works for some implementations of JSF.

answered Apr 14, 2011 at 16:44

aseychell

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2 Comments

BalusC Over a year ago

This is not JSF specific. This is EL specific.

aseychell Over a year ago

Yes you are right. But I knew it was possible in some cases :)

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