Convert string to lowercase for property binding within xhtml?

Question

How could I always convert the property username to lower case?

This does not work:

<h:inputText value="#{userService.user.username.toLowerCase()}" />

as target gets "unreachable" by this. How could I else do this?

how bout changing its getter `return username.toLowerCase();` (do some null check too) — Daniel, Oct 30 '12 at 08:36

BalusC · Accepted Answer · 2016-01-13T18:39:54.993

8

<h:inputText value="#{userService.user.username.toLowerCase()}" />

You can't perform a "set" operation on the given EL expression, while this is mandatory in order to update the model value with the submitted value. The toLowerCase() method expression doesn't have a corresponding setter method.

Technically, you should be creating a Converter for the job. Here's a kickoff example:

@FacesConverter("toLowerCaseConverter")
public class ToLowerCaseConverter implements Converter {

    @Override
    public String getAsString(FacesContext context, UIComponent component, Object modelValue) {
        if (!(modelValue instanceof String)) { 
            return null; // Or throw ConverterException.
        }

        return ((String) modelValue).toLowerCase();
    }

    @Override
    public Object getAsObject(FacesContext context, UIComponent component, String submittedValue) {
        if (submittedValue == null) { 
            return null;
        }

        return submittedValue.toLowerCase();
    }

}

Use it as follows:

<h:inputText value="#{userService.user.username}" converter="toLowerCaseConverter" />

You should preferably not clutter the model with conversion strategies.

edited Jan 13 '16 at 18:39

answered Oct 30 '12 at 09:01

BalusC

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Which converter is extended here? `import org.apache.myfaces.config.element.Converter;` would not work here as it would require a lot of override methods like `getConverterClass` `getConverterId` `getForClass` – membersound Oct 30 '12 at 09:39
Just the standard JSF converter. Have you never created one? It's the [`javax.faces.convert.Converter`](http://docs.oracle.com/javaee/6/api/javax/faces/convert/Converter.html). – BalusC Oct 30 '12 at 09:41
Ok we have to use *implements* here instead extends. Then it works, additionaly changing the *void* to String or Object. – membersound Oct 30 '12 at 09:42
Oops, sorry for that. Didn't had enough coffee at 05:00 am. Answer is been fixed. I should have used an IDE instead of the SO message editor. – BalusC Oct 30 '12 at 09:43
no problem, anyway this is probably the best solution for lower case. It worked of course with the conversation within the setter, but as you said cluttering the model should be avoided. – membersound Oct 30 '12 at 09:44
One more suggestion to have a complete example here: `if (!(value instanceof String)) { return ""; }` as we cannot return an object if method is a String. – membersound Oct 30 '12 at 09:47
@ᴠɪɴᴄᴇɴᴛ: I usually don't add imports unless there's ambiguity. Just let IDE autocomplete imports and verify if it compiles. Moreover, the `Converter` link in my answers points to the javadoc. – BalusC Jan 12 '16 at 20:51
@ᴠɪɴᴄᴇɴᴛ: missed that due to the double comment, I only saw last one. – BalusC Jan 13 '16 at 18:40

Kishor Sharma · Answer 2 · 2012-10-30T09:01:00.347

4

You can use jstl function for this

include: <%@ taglib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn" %>

and use < h:inputText value="${fn:toLowerCase(string)}"/>

Or you can make username in lowercase in java by .toLowerCase().

edited Oct 30 '12 at 09:01

answered Oct 30 '12 at 08:37

Kishor Sharma

599
8
15

Wrong. You cannot perform a "set" operation on a function expression. – BalusC Oct 30 '12 at 08:57

score 1 · Answer 3 · answered Oct 30 '12 at 08:37

1

This way should work. As soon as you set the name, the name is lowecased.

String name;

public void setName(String name){
 this.name = name.toLowerCase();
}

answered Oct 30 '12 at 08:37

Averroes

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Convert string to lowercase for property binding within xhtml?

3 Answers3