What are the rules for a JSF id?

Question

It seems like I should be able to find this with a half hour of searching the webs, but since I cannot:

What are the rules for valid JSF ids?

I read a garbled e-mail message that suggested there were limitations on - and _, but I'm getting IllegalArgumentExceptions and I think it's due to the ids.

EDIT

java.lang.IllegalArgumentException: 6a945017207d46fd82b3d3bb7d2795f1
at javax.faces.component.UIComponentBase.validateId(UIComponentBase.java:549)
at javax.faces.component.UIComponentBase.setId(UIComponentBase.java:351)
at com.sun.facelets.tag.jsf.ComponentHandler.apply(ComponentHandler.java:151)

Why don't you just post the exception stacktrace and the code snippet that caused it? — BalusC, May 12 '11 at 01:37
I don't think I can par down the example to anything reasonably simple that would demonstrate the issue, but I'll attach the stack trace. — Adam, May 12 '11 at 01:39

score 18 · Accepted Answer · edited Jun 20 '20 at 09:12

18

It has to be a valid CSS identifier (the ident here) and there should be no duplicates.

In CSS, identifiers (including element names, classes, and IDs in selectors) can contain only the characters [a-zA-Z0-9] and ISO 10646 characters U+00A1 and higher, plus the hyphen (-) and the underscore (_); they cannot start with a digit, or a hyphen followed by a digit. Identifiers can also contain escaped characters and any ISO 10646 character as a numeric code (see next item). For instance, the identifier "B&W?" may be written as "B\&W\?" or "B\26 W\3F".

private static void validateId(String id) {
    if (id == null) {
        return;
    }
    int n = id.length();
    if (n < 1) {
        throw new IllegalArgumentException("Empty id attribute is not allowed");
    }
    for (int i = 0; i < n; i++) {
        char c = id.charAt(i);
        if (i == 0) {
            if (!Character.isLetter(c) && (c != '_')) {
                throw new IllegalArgumentException(id);
            }
        } else {
            if (!Character.isLetter(c) &&
                    !Character.isDigit(c) &&
                    (c != '-') && (c != '_')) {
                throw new IllegalArgumentException(id);
            }
        }
    }
}

It's however a little more strict than the CSS rules. They cannot start with a hyphen as well.

edited Jun 20 '20 at 09:12

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answered May 12 '11 at 01:38

BalusC

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BINGO! can't start with a digit! I appreciate the whole page because I could spend all day replaceing characters and appending text and not get all the rules right 100% of the time. Thanks – Adam May 12 '11 at 01:40
@BalusC is there any reason, to be more restrictive than [HTML rules](http://stackoverflow.com/a/79022/1099452)? Only to allow easier CSS selection? – lucasvc Oct 07 '15 at 15:12
@lucasvc: HTML rules allow `:`, which conflicts naming container separator character. – BalusC Oct 07 '15 at 15:15
@BalusC But container separtor, can be configured, right? And in my case, the problem is with period / dot / `.`. – lucasvc Oct 08 '15 at 05:26
1

@lucasvc: it was only since JSF 2.0 configurable. – BalusC Oct 08 '15 at 07:32
Still, `update=":form-list-users:table-list-users"` cannot be solved. And I was about to rename my ids again. Almost all of them have `-` and still some have `_` in their names. Else only `[a-z]` is included, no numbers at all. `table-list-users` is a `p:dataTable`. – Roland Sep 28 '17 at 20:02
1

@Roland You have actually a different question than the one asked here. Move on to https://stackoverflow.com/q/8634156 – BalusC Sep 29 '17 at 07:55
Yes, maybe it is. I found already the fix for it: I used `p:page` which adds another id fragment to the final id `update` requires. So I set `p:page id="master"` and I can use `update=":master:what-ever-here"` successfully. Thank you replying anyway. – Roland Sep 29 '17 at 19:15

What are the rules for a JSF id?

1 Answers1

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