[jsr-314-open] Handling of "" vs null action outcomes

[Andy Schwartz]

Quick update... I logged the following spec issue to track this:

https://javaserverfaces-spec-public.dev.java.net/issues/show_bug.cgi?id=747

Andy

Andy Schwartz wrote:
> Gang -
>
> One of our unit tests here at Oracle tripped up over a small change in 
> behavior between JSF 1.2 and JSF 2. The unit test contains an action 
> method that returns an empty string, eg:
>
> <h:commandButton action="#{foo.doSomething}"/>
>
> public String doSomthing()
> {
> // Do something here
>
> return "";
> }
>
> When running against JSF 1.2, the empty string outcome would result in 
> the test case remaining on the same page, as there is no navigation 
> case that matches this outcome. In JSF2, implicit navigation kicks in. 
> In particular, the following statement from section 7.4.2 is applied:
>
>> If viewIdToTest does not begin with “/”, take the current viewId and 
>> look for the last “/”. If not found, prepend a “/” and continue. 
>> Otherwise remove all characters in viewId after, but not including, 
>> “/”, then append viewIdToTest and let the result be viewIdToTest.
>
>
> In our case, we have the following values:
>
> - Current viewId: "region/refresh".
> - viewIdToTest: ""
>
> The resulting view id after applying the above logic is "region/". 
> This ends up being treated as an implicit view id. In our particular 
> test case, there is no view associated with this view id. Instead of 
> remaining on the same page, we now attempt to navigate to a view that 
> does not exist.
>
> Our test case made the assumption that returning the empty string from 
> the outcome would result in the same behavior as returning null. This 
> was true in JSF 1.2, but no longer appears to be true in JSF2. We have 
> tweaked this unit test to return null so that our tests are now 
> passing, but I wanted to follow up to find out whether this small 
> difference in behavior between "" and null outcomes is intentional. It 
> seems to me that these should behave the same. It would be easy enough 
> for us to add a sentence to the spec that states that empty string 
> outcomes should not be treated as implicit view ids. Does anyone here 
> know of a reason why we shouldn't spec this?
>
> FWIW, my feeling is that, while returning null is a reasonable 
> workaround, there is no way that our unit test is not the only code 
> out there that is returning empty action outcomes and expecting to 
> stay on the same page. I would like to see this behavior preserved not 
> so that we can revert our unit test to its previous behavior (I am 
> fine with our fix), but because the current behavior may break other 
> users as they upgrade to JSF2.
>
> Thoughts?
>
> Andy
>