EL and accessing .size or isEmpty

tony.herstell1 May 4, 2007 6:18 PM

A coding question ... with EL how do I get to things like .size.. or .isEmpty its seems very hard to get to!!!

I have this...

<h:outputText value="#{messages.no_keywords}" rendered="#{advertisingCampaign.keywords == null}"/>

and want this

<h:outputText value="#{messages.no_keywords}" rendered="#{advertisingCampaign.keywords == null || advertisingCampaign.keywords.size == 0}"/>

But size is "not a property" and incidently nither is isEmpty !!!

keywords is a LinkedHashSet (to ensure retreival order matches insertion order) and I am pretty sure that this is NOT a factor...

1. Re: EL and accessing .size or isEmpty

stu2 May 5, 2007 12:38 AM (in response to tony.herstell1)

You can use the empty keyword, like this:

#{advertisingCampaign.keywords == null || empty advertisingCampaign.keyword}
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2. Re: EL and accessing .size or isEmpty

hstang May 5, 2007 12:40 AM (in response to tony.herstell1)
Use Facelets' built-in Jstl Function library.

<h:outputText value="#{messages.no_keywords}" rendered="#{fn:length(advertisingCampaign.keywords) == 0}"/>

make sure you register the namespace for fn

i.e
<html xmlns:fn="http://java.sun.com/jsp/jstl/functions">
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3. Re: EL and accessing .size or isEmpty

tony.herstell1 May 5, 2007 12:53 AM (in response to tony.herstell1)

Thanks guys excellent solutions.
I discovered a workaround which was to use "another" DataModel to to hold these.
Seems overkill as its only for displaying them as text (no buttons, line row selections etc.), so I will refactor to use one of the solutions above.
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