How to conditionally invoke a4j:commandButton oncomplete script depending on action outcome

Question

I have a

<a4j:commandButton action="#{myBean.doCalculation}"
                   oncomplete="redirectBrowser()" />

However, if there is an error at myBean.doCalculation(), then oncomplete attribute is always invoked. How do I let it depend on result of action method?

score 4 · Accepted Answer · edited May 16 '16 at 07:12

4

You can check for errors in the oncomplete event and redirect when none are found. It can be done like this

oncomplete="#{facesContext.maximumSeverity == null ? 'redirectBrowser()' : 'doSomethingElse()'}"

edited May 16 '16 at 07:12

Alexandre Lavoie

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answered Apr 01 '11 at 14:24

Giorgos Dimtsas

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There is really no problem with a4j:commandButton and navigation - it's not designed to be used for navigation. One option is to use for navigation. – Max Katz Apr 05 '11 at 16:33

score 3 · Answer 2 · answered Jan 17 '12 at 18:45

3

If you're on JSF 2.0, you can use FacesContext#isValidationFalied() to check if validation has failed or not:

oncomplete="if (#{not facesContext.validationFailed}) redirectBrowser()"

However, just performing redirect in the action method is more clean:

public String doCalculation() {
    // ...

    if (success) {
        return "nextPage.xhtml?faces-redirect=true";
    } else {
        return null;
    }
}

Yet more clean would be to just do the validation by a Validator. This way the action method will simply not be invoked at all when the validation has failed.

answered Jan 17 '12 at 18:45

BalusC

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Thanks for this answer! It was very helpful. To respectfully disagree with one point, doing the redirect in the action method is less clean -- IMHO allowing redirection by returning a string is a design flaw in Faces... – wprl May 11 '12 at 20:51
2

It's absolutely not a design flaw. PRG is one of the most commonly used web design patterns: http://en.wikipedia.org/wiki/Post/Redirect/Get However, using POST forms for *plain vanilla* navigation from page X to page Y is in turn absolutely a design flaw (by the developer, not by JSF). See also http://stackoverflow.com/questions/4317684/when-should-i-use-houtputlink-instead-of-hcommandlink – BalusC May 11 '12 at 20:52
Sorry, lazy's not the word I was looking for. Nothing wrong with PRG; it's just a clunky syntax is what I'm getting at. It seems odd to return a string rather than call some redirect method. – wprl May 11 '12 at 21:23

score 2 · Answer 3 · answered Jan 17 '12 at 16:48

2

Well, just looking for facesContext.maximumSeverity == null is not enough, there may be a warning as current max severity, that should redirect, too. Instead, write a method that looks if there are any max severities of priority error...

answered Jan 17 '12 at 16:48

Jens Kreidler

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How to conditionally invoke a4j:commandButton oncomplete script depending on action outcome

3 Answers3