9 Replies Latest reply on Apr 29, 2011 12:02 PM by nbelaevski

How to walk the viewroot before render response?

tomba Feb 3, 2011 6:08 AM

For various reasons, I need to change some attributes on a few components before my facelet is rendered to the browser. Hence, I'm doing this in beforePhase of RENDER_RESPONSE, and it works nicely on a POST request (so when running through the completely JSF lifecycle).

However... I want to also apply my rules when I request a page for the first time. In that case, jsf processing jumps immediately to render_response, and in the beforephase of that, the ViewRoot is not filled in (it doesn't have any child components).

I tried adding a public buildView() method to the faceletviewhandler, but I have now found that org.ajax4jsf.event.InitPhaseListener wraps it with an AjaxViewHandler, hard coded in the phase listener.

Hence a few questions:

- Is there a way that I can build the viewroot earlier, even on a normal GET request?

- Or how can I implement my own InitPhaseListener to make sure it can use my own ViewHandler?

Thanks,

Steven

1. How to walk the viewroot before render response?

tomba Feb 4, 2011 4:17 AM (in response to tomba)

No straightforward solution then?
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2. Re: How to walk the viewroot before render response?

boy18nj Feb 5, 2011 3:01 PM (in response to tomba)

Hi Steven,

If you want to walk the viewroot before rendering response, you need to use system event, do something like this-

<f:view>
<f:event type="preRenderView" listener="#{user.changeLocale}"/>
<h:head>
<title>...</title>
</h:head>
<h:body>
...
</h:body>
</f:view>

public String changeLocale(ComponentSystemEvent event) {
FacesContext context = FacesContext.getCurrentInstance();
context.getViewRoot().setLocale(new Locale(languageCode));
return null;
}

Note that system events are available only in JSF 2.0
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3. How to walk the viewroot before render response?

nbelaevski Feb 6, 2011 7:05 AM (in response to tomba)

Hi Steven,

Try specifying phaseListener via view root attribute (f:view tag). This will work in JSF 1.2
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4. How to walk the viewroot before render response?

tomba Feb 6, 2011 6:21 PM (in response to nbelaevski)

Aman, I'm aware of the system but I'm stuck with JSF1.2 for now.

Anyway, in my case context.getViewRoot() is not null either, so I could do a setLocale() without problems. However, context.getViewRoot().getChildren() is empty in beforephase(RENDER) when it's a regular GET request. And my problem is exactly that I need to loop the children in the beforephase or RENDER_RESPONSE...

Nick, will a phaselistener on f:view make a difference from one specified in faces-config? I would find that very odd, but I can try...

Thanks
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5. How to walk the viewroot before render response?

nbelaevski Feb 6, 2011 7:26 PM (in response to tomba)

Yes, different. As a complete solution, you can use PhaseListener declared in faces-config.xml to add PhaseListener to created view root,
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6. Re: How to walk the viewroot before render response?

tomba Feb 7, 2011 5:14 AM (in response to nbelaevski)

Nick, I'm stunned.
Previously I had my listener added to the faces-config.xml, but my viewroot had 0 children every time I was in beforephase (render) on a GET request.

Now, by adding <f:phaseListener type="...."/> within the <f:view>...</f:view>, things are now working properly.
I'm still curious to know why this is. Can you explain that?
It's also annoying, as this would require me to add this <f:phaseListener> element to each of my pages
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7. Re: How to walk the viewroot before render response?

nbelaevski Feb 7, 2011 5:28 AM (in response to tomba)

Steven,

This is how JSF works - see details in spec.

And once again:

>> As a complete solution, you can use PhaseListener declared in faces-config.xml to add PhaseListener to created view root/
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8. Re: How to walk the viewroot before render response?

tomba Apr 29, 2011 11:43 AM (in response to nbelaevski)

After running this solution for a bit, I have bumped into a strange problem where ui:repeat appears not to be expanded when my phaselistener in before RENDER_RESPONSE kicks in. Hence, at the time I run through the components in the phaselistener, I have only one component in the repeat, whereas on screen I get 8 elements in the repeat (the latter being correct as I have 8 elements in the list).

Still trying to work out why exactly, but do you have any idea why ui:repeat seems to behave differently from other JSF components?
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9. How to walk the viewroot before render response?

nbelaevski Apr 29, 2011 12:02 PM (in response to tomba)

Steven,

ui:repeat is one of so-called 'stamped' components - only one instance of component (with children components) is present in component tree, and nested components are processed inside iteration.
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