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How to troubleshoot "duplicate Id for a component" errors?

 
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When I'm iterating through building a new page, I often get "duplicate Id for a component" while constructing pieces of the page. When I get this, I have to guess where I'm having an "id" problem. I've never actually specifically set two fields with the same "id" value, this error only really happens when the framework generates two fields that result in the same "id" value. The problem is, how the heck do you figure out what you did wrong that produces that error? I usually have to hunt around on the whole page to figure this out.

For instance, here is a page that I'm working on:

<%@ taglib uri="http://richfaces.org/a4j" prefix="a4j"%>
<%@ taglib uri="http://richfaces.org/rich" prefix="rich"%>
<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h"%>
<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f"%>
<html>
<head>
<title>TabPanel Experiment</title>
</head>
<body>
<f:view>
<a4j:form>
<rich:tabPanel id="tabpanel" switchType="client">
<rich:tab name="obligor" label="Obligor">
<h:panelGrid columns="2" id="obligorFields">
<h:column>Field1:</h:column>
<h:column><h:inputText id="field1"/></h:column>
</h:panelGrid>
</rich:tab>
<rich:tab name="property" label="Property">
<h:panelGrid columns="2" id="propertyFields">
<h:column>Field2:</h:column>
<h:column><h:inputText id="field2"/></h:column>
</h:panelGrid>
</rich:tab>
<rich:tab name="ratings" label="Ratings">
<h:panelGrid columns="2" id="ratingsFields">
<h:column>Field3:</h:column>
<h:column><h:inputText id="field3"/></h:column>
</h:panelGrid>
</rich:tab>
</rich:tabPanel>
</a4j:form>
</f:view>
</body>
</html>


This produces "duplicate Id for a component _id0:_id1". In general, how do I figure out how to fix these errors?
 
Ranch Hand
Posts: 3389
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Hi David,

I am not too sure whether this would help you or not. One plausible solution what i can think of is, don't let the runtime generate an id for your component. You try to always associate an id with the component.
 
Ranch Hand
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Raghavan Muthu is right you always try to set the ID of a component when you create this. what i normally do is setting the Id to the component name+ line number where its located. but you can come up with your own style

 
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This probably indicates that the JSF libraries you are using have bugs in them.

I recommend setting explicit IDs on your page elements as much as is practical. That way if you get a JSF error, it's easier to backtrack it to the defective component (just look for its ID).

Many XML editors will flag duplicate instances of the same user-assigned ID, so that's another plus.
 
Raghavan Muthu
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That's great guys. That's how i worked in JSF initially which was 2 yrs back
 
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