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Re: Help with custom tag attribute

by FkJ :: Rate this Message:

Thanks for the help.

I'll try to explain better. My component doesn't have a Java class, its only a tag. It looks like this:

<ui:composition
    xmlns:h="http://java.sun.com/jsf/html"
    xmlns:ui="http://java.sun.com/jsf/facelets"
>
    <h:panelGrid
        columns="2"
        cellpadding="0"
        cellspacing="0"
    >
        <h:selectBooleanCheckbox
            id="#{id}"
            value="#{value}"
        >
            <ui:insert />
        </h:selectBooleanCheckbox>
        <h:outputLabel
            value="#{label}"
            for="#{id}"
        />
    </h:panelGrid>
</ui:composition>

The id attribute is expecting a value, so every time I use the component I have to set it, otherwise I'll get an IllegalArgumentException. If I hardcode the id I'll get a duplicated id exception if I have more than 1 component on the page. If I had a Java class for the component I could simply do something like this:

if(id != null && !id.trim().isEmpty())
{
component.setId(id);
}

How to achieve this on the tag? As I mentioned above f:attribute is not working as expected.

Thanks,
Felipe

2009/6/19 Fırat KÜÇÜK <firatkucuk@...>

Hi,
i didn't understand exactly what you mean. But may be this will helps you.

this is my jsf managed bean:
-----------------------------
package mypackage;

public class Sample {

private String label = "label";
private String value = "value";
private int id = 0;

public Sample() {
}

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

public String getLabel() {
    return label;
}

public void setLabel(String label) {
    this.label = label;
}

public String getValue() {
    return value;
}

public void setValue(String value) {
    this.value = value;
}

public String submit() {
    label = value;
    return null;
}
}

--------------------------------------------------
and this is facelets file:

<?xml version='1.0' encoding='UTF-8' ?>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"

      xmlns:c="http://java.sun.com/jstl/core"
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:ui="http://java.sun.com/jsf/facelets"
      xmlns:h="http://java.sun.com/jsf/html">

<body>
    <h:form>
      <h:outputLabel value="#{sample.label}" />
      <h:outputLabel value="#{sample.id}" />
      <h:messages />
      <h:inputText label="#{sample.label}" value="#{sample.value}">
        <f:convertNumber />
      </h:inputText>
      <h:commandButton value="submit" action="#{sample.submit}">
        <c:if test="#{!empty sample.id}">
          <f:setPropertyActionListener target="#{sample.id}" value="#{sample.value}" />
        </c:if>
      </h:commandButton>
    </h:form>
</body>
</html>

2009/6/19 Felipe Jaekel <fkjaekel@...>

Actually the problem is that f:attribute is not evaluating the the EL. If I pass the value literally it accepts, but if I pass #{maxlength} it is trying to set the string "#{maxlength}" as maxleght, so thats why the I get the ClassCastException.

<h:outputLabel value="#{label}" />
    <h:inputText
        label="#{label}"
        value="#{value}"
    >
        <c:if test="#{! empty id}">
            <f:attribute
                name="id"
                value="#{id}"
            />
        </c:if>
        <ui:insert />
    </h:inputText>

The id attribute is a better exemple of what I'm trying to do. When it's not set in the custom tag I'd like that it is not set in the h:inputText tag so that JSF generates the id. Otherwise always when I use the custom tag I'll have to set the id or write some crazy workaround to generate it so that I don't get a duplicated id exception.

Any ideias? Does f:attribute only accepts literals?

Thanks,
Felipe

2009/5/6 joseph j marini <josephjmarini@...>

Try mapping value to a backing bean #{foo.maxLength}
in your backing if max length is optional return null, else return
Integer object with value set. It will get converted automatically.

/Joe

--------------------------------------------------
From: "Zarar Siddiqi" <zarars@...>
Sent: Wednesday, May 06, 2009 11:26 AM
To: <users@...>
Subject: Re: Help with custom tag attribute

There's a difference between saying something is optional by passing
in a null, entirely another to pass in a string and expect it to be
ignored just because its not an integer.

What is the value of maxlength when you pass it in? Is it null or a string?

On Fri, Apr 24, 2009 at 1:16 PM, Felipe Jaekel <fkjaekel@...> wrote:

I have a custom tag that is composed by a <h:outputLabel /> + <h:inputText
/>. I need the maxlength attribute to be optional. The problem is that when
I use <f:attribute /> I get a class cast exception.

Tag:

<ui:composition
xmlns:h="http://java.sun.com/jsf/html"
xmlns:c="http://java.sun.com/jstl/core"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:ui="http://java.sun.com/jsf/facelets"
>
<h:outputLabel value="#{label}" />
<h:inputText
label="#{label}"
value="#{value}"
>
<c:if test="#{! empty maxlength}">
<f:attribute
name="maxlength"
value="#{maxlength}"
/>
</c:if>
<ui:insert />
</h:inputText>
</ui:composition>

Exception:

java.lang.ClassCastException: java.lang.String cannot be cast to
java.lang.Integer

Any ideas?

Thanks,
Felipe

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FIRAT KÜÇÜK

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