JSF unable to set dynamic id for input component

my form looks like this:

When the user clicks "+ Add" a new distance input shows up:

The user can repeat this operation as many times as desired, but all distances must be filled in, and individual messages must be served for missing data:

So i'm trying to stablish dynamic ids for the distance inputs. However, when i try to pass dynamic values everything fails. up to now i've tried two diff开发者_开发知识库erent techniques:

• using the binding HtmlDataTable's rowIndex <- it always shows -1
• setting the id as an attribute of the Distance class <- ugly exception

here's my code:

Backing bean:

private List<Distance> distances;
private HtmlDataTable distancesUI;

public void addDistance(ActionEvent e) {
    distances.add(new Distance());
}

JSPX:

<h:dataTable
binding="#{Bean.distancesUI}"   
value="#{Bean.distances}"
var="distance"> 
    <h:column> 
        <h:inputText 
        id ="distance_#{Bean.distancesUI.rowIndex}" // <- always renders "distance_-1"
        value="#{distance.value}" />
    </h:column>
</h:dataTable>

I need to be able to show individual "required" messages. Any ideas?

thanks in advance

I need to be able to show individual "required" messages. Any ideas?

For that you don't need to fiddle with IDs. JSF will do it for you. Just do

<h:dataTable id="table" value="#{bean.distances}" var="distance"> 
    <h:column> 
        <h:inputText id="distance" value="#{distance.value}" required="true" />
        <h:message for="distance" />
    </h:column>
</h:dataTable>

This will end up in generated HTML like follows:

<table id="form:table">
    <tr><td><input id="form:table:0:distance" /></td></tr>
    <tr><td><input id="form:table:1:distance" /></td></tr>
    <tr><td><input id="form:table:2:distance" /></td></tr>
    ...
</table>

Rightclick the page in browser and choose View Source to see it yourself.

Any validation error will just be shown in the same row as the input.