Question

I’m trying to call a method on a grails service from a controller, but it looks like execution is just skipping the method call.
I’ve tried debugging the application with a breakpoint inside the method but it is never hit.

My service (generated with grails create-service) is:

class FormatterService {
    static transactional = false

    def formatList (List<Host>, String fmt) {
        OutputObject somePOGO = new OutputObject();
        (snip)
        return somePOGO
    }
}

Then on my controller I have:

class HostController {
    def formatterService

    def getHostsByLabels = {
        (snip)
        OutputObject o = formatterService.formatList(someHosts,params.format)
        (snip)
    }
}

When the formatterService.formatList method should be called in the controller, execution simply skips to the next line, no output is printed to the console and breakpoints within the method are not hit. The OutputObject o reference is null afterward.

What is wrong here? It could be a really basic mistake from my part, but I just can’t put my finger on it…

Answer 1

I found the issue. It has to do with the method signature.

Printing out the thrown exception’s message, it says:

No signature of method: hms.FormatterService.formatList() is applicable for argument types: (java.util.TreeSet, java.lang.String) values: (...)
Possible solutions: formatList(java.util.List, java.lang.String)

So, a rookie mistake (wanting to pass a TreeSet for a List) aided by weak typing in Groovy… 😛

I’ve changed the method signature to

def formatList ( items, String fmt) {

and call it as

def activeHosts = ...
OutputObject o = formatterService.formatList(activeHosts, params.format as String)

and now it works.