Getting rid of "value" attribute in f:selectItems?

Question

Hello,
There is a simple problem I am facing at work that is actually hurting us significantly... we have a JSF 1.1 (yes, it's very old!) situation where we need to present a page that has a very long dropdown list, more than 5000 options in it. The problem is that the options are very long, and the entire page ends up being over 600Kb in the browser, and worse than that the application server gobbles up massive amounts of RAM just to generate the page.
One optimization we want to do is to take advantage of the following fact: all of the options have values that match the labels. In other words, our options look like this:
<option value="longString1">longString1</option>
<option value="longString2">longString2</option>
<option value="longString3">longString3</option>
We'd like to reduce the page by 50% with a simple optimization: suppress the value attributes like the following:
<option>longString1</option>
<option>longString2</option>
<option>longString3</option>
We are generating these options in an ArrayList of SelectItems, and using an f:selectItems to generate the HTML... but we have NOT figured out how to suppress the value attributes. Try as we might, we are unable to remove them... Is there any way to get:
<f:selectItems ...>
to just display the labels???
Or is there another approach we should use??
Thanks in advance.

Answer 1

Hi,
Can't help specifically with JSF 1.1 I'm afraid, but in 2.0 you need to supply a custom renderer to achieve this. The default MenuRenderer will always write out the value attribute, as per the following code:
// com.sun.faces.renderkit.html_basic.MenuRenderer
protected boolean renderOption(...) {
  ResponseWriter writer = context.getResponseWriter();
  writer.startElement("option", component);
  writer.writeAttribute("value", valueString, "value");
  writer.write(curItem.getLabel());
  writer.endElement("option");
}I achieved an option list with no value attributes by extending this class, overriding the renderOption method, commenting out the writeAttribute line, and setting that as the default renderer for the SelectOneMenu. Like I said, this was JSF 2, but maybe a similar approach would work for JSF 1.1?
On a completely different approach, how often do the values in the list change? If they are infrequent, then maybe you could use something like the following:
- dynamically create a javascript file that holds the data, plus a method to build an option list from this data
- include a reference to this javascript file in the page header
- create a custom tag in the page which uses the javascript to build the option tags
The advantage of this is that you can let the browser cache the big javascript file with all the options in it, and only include a link to it and a call to the javascript function in the page data. If required, you can add a sequence number to the javascript link to force the browser to reload it when the data changes.
Obviously, you still get the hit the first time you load the list (although the data here is much more concise, as you don't need to send the XML tags at this point and also you only need to send each value once), and it's not as useful if your data changes frequently. Also dumps some processing on the client side, but that sounds like it would be a good thing in your case!
I've used this approach in other situations where I had to repeatedly push a lot of static data to the client. Never actually used it from JSF, but the principle is still valid. Let me know if you think it would be useful; sure I've still got the old javascript lying around somewhere
Cheers,
Barney
@EJP / qimbal2: The OP asked a pretty specific question: "how to render a dropdown list without the value attribute", which is a perfectly valid question. Yes, we can all see that 5,000 items in a drop down list is not ideal, and I understand that anyone answering questions like these is generally doing so on their own time, but just stating that the design sucks isn't really helping.