Rendered attribute of commandButton preventing action method from executing

Question

When I add a rendered tag to my commandButton it'll only execute the method intermittantly. After a lot of testing, I've narrowed down the problem so I now know when it does and does not work properly.
If rendered="true" it always works fine
If rendered="#{issue.update}" and isUpdate() is simply "return true;" it'll always work correctly
If rendered="#{issue.update}" and isUpdate() is simply "return this.getId() != 0;" it will not execute the action specifiied, however the page does refresh.
It's also interesting to note that on the rendered page, the button is always shown only when it should be. So when the action fails to execute, the button is shown on the screen.
In the case that doesn't work, I debugged through and noticed that isUpdate() is called six times for a single page refresh. By printing a stacktrace for each call, I discovered that it's called once in the ApplyRequestValues stage of the lifecycle and the other five times are from RenderResponse (I have the stacktraces, let me know if they'd be worth posting). This method is only referenced once and only on the jsf page, never in the java code... but I'll go back and try to understand why it's calling it so many times later.
The first time isUpdate() is called, it will retrun false because the value for id has not yet been assigned, which makes sense. This causes a "false" to be returned from isUpdate() and this is what is causing the action to not be executed. If I debug through and change the return value to be true here (only the first time) the action is updated. So my question is, what's going on here? I don't understand why is isUpdate() called so many times, why is it called so early in the lifecycle, and why the call in the apply request values stage determines whether or not it executes the action?
Now, as a workaround, I put a binding on the id, and tried to use that value. That exposed another problem with my page which requires some explanation... Here are the relevent sections of the page and backing bean...
issue.jsp
<h:outputText value="#{issue.init}" />
there's a datatable here which displays all issues and has a commandLink to edit the issues (immediate="true"). It posts back to this page and passes an ID on the URL.
<h:inputHidden id="id" value="#{issue.id}" binding="#{issue.idBinding}" />
<h:inputText id="name" value="#{issue.name}" required="true" />
<h:commandButton id="updateIssue" value="Update" action="#{issue.updateIssue}" rendered="#{issue.update}" />
Issue.java
getInit() will get the id from the FacesContext (specifically, the URL) and load the data from the database.
On the rendered page in my web browser:
After clicking on an edit link, the page is loaded and the name is filled in, the update button is on the screen, and everything looks good.
When I view source, I see that the hidden input for id is set to zero. I'm still trying to figure out why this is the case since all the other parameters are set properly. I stepped through getInit() and it is, indeed setting the id property properly.
So when I added the binding to get the value from there instead of via the local values, I found that it always got zero (presumedly because that's what is rendered in the HTML code). This means that isUpdate() still returns false on the first call, and my attempt at a workaround fails! So, just as a test, I used some "javascript on the URL" trickory to set the id field to "10". That worked just fine. So the root of the problem is that issue.id is not loading. I put code in the getId() method to always look at the binding and then faces context and put the id into this.id if it found a non-null and non-zero value. It now returns the correct value all of the time but the HTML produced still says the value is zero.
I've spent about 4 hours on this issue and I'm to the point where I need advice from someone who is more educated on how JSF works. I know the inputHidden get the vaule for the HTML tag it produces from getId() because when I hard code that to always return 10, it works. But when I leave it to return the proper value, the debug statements say it's returning the proper value, but the HTML always says it's zero. This isn't an acceptable solution anyway because I use getId() in the datatable to display the IDs of each of the issues; I just wanted to see if it'd work and it didn't.
Here's my latest getInit() method (which returns the value from the URL when called from the datatable, but not when called from the inputHidden.
    public int getId() {
        if(getIdBinding() != null && !getIdBinding().isLocalValueSet()) {
            if(getIdBinding().getSubmittedValue() != null) {
                int temp = Integer.parseInt((String)getIdBinding().getSubmittedValue());
                if(temp != 0) {
                    this.id = temp;
                    log.info("Got binding value of "+this.id);
        FacesContext ctx = FacesContext.getCurrentInstance();
        if(ctx != null) {
            Map<String, String> map = ctx.getExternalContext().getRequestParameterMap();
                if(map != null) {
                String given_id = map.get("id");
                if(given_id != null) {
                    // if given an ID and no action, we load the data
                    try {
                        log.info("Got value from FacesContext of "+given_id);
                        int temp = Integer.parseInt(given_id);
                        if(temp != 0)
                            this.id = temp;
                    } catch(NumberFormatException e) {
                        // if what's passed in isn't an integer, we leave everything at default values
        return this.id;
    }Thanks in advance,
Adam

Answer 1

I'm clicking a link which will load data into a form. In the form there is a field called "id" which has a value of something other than zero. I press the update button (which is only rendered when the id is non-zero), it submits the form. When the restore view happens, the id is the default value of 0 because it has not yet applied the values from the form to the backing bean. Therefore the rendered attribute of update button (isUpdate()) will return false, and the update() method does not get queued.
When I switch my backing bean to session level, the restore view already has the id loaded, even before the values from the form are applied, so everything works as expected. The problem was that I needed to have the correct return values before any values have been loaded into the member variables.
As a solution to this, I made some private boolean variables called isNew and isUpdate. Both of them are true by default. This makes sure that the isNew() and isUpdate() methods (attached to the render attribute of my command buttons) return true in the restore view phase. When I read in the id from the URL or hidden input, it'll update the boolean values accordingly, which makes sure the buttons are rendered properly. This allowed me to set the backing bean back to the request scope, which make me happy. <img class="emoticon" src="images/emoticons/grin.gif" border="0" alt="" />
Thank you Mr. De Campo. You gave me exactly what I was looking for... a better understanding of how thigns work, and (indirectly) a clean solution to my problem.