If you’ve used Rails, you’re familiar with the flash, and all the nifty things you can do with it.

In Grails, you have flash, but you also have an entire tag library of <g:hasError>, <g:renderErrors> and so forth. None of which, as far as I can tell, care one whit about the flash. They’re all focused on domain objects, and the errors associated with processing them.

(In my opinion, this is one of the frustrations of Grails examples - the tendency to get the domain connected to the view via scaffolding, and then the author changes the subject)

But you can use the flash, in much the same way as Rails. For example, I put the following in my top-level layout template:

              <g:if test="${flash.error}">
                 <div class="errorbox">
                    ${flash.error}
                 </div>
              </g:if>

              <g:if test="${flash.message}">
                 <div class="messagebox">
                    ${flash.message}
                 </div>
              </g:if>

(note that you’ll have to define the messagebox and errorbox css classes)

Putting information into the flash is straightforward:

     flash.error = "Your error message here."

Hope this helps!