Override a template method in scaffolded controllers

Question

I have a Grails project where I use heavily customized scaffolding templates to add a beforeUpdate template method to update so that I can easily customize scaffolded Controller's without having to generate and then edit each controller separately.

Unfortunately this doesn't work and only beforeUpdate from scaffolding gets called. I suspect it has to do with the code generation used by Groovy to inject the scaffolding code into the actual Controller, but I can't find any confirmation.

What I'm asking is either a solution to the problem or an explanation for why it doesn't work.

Here is the scaffolding code:

def beforeUpdate = {
    println "beforeUpdate from scaffold"
}

def update() {
    // call before update hook
    beforeUpdate()

    def ${propertyName} = ${className}.get(params.id)
    if (!${propertyName}) {
        flash.message = message(code: 'default.not.found.message', args: [message(code: '${domainClass.propertyName}.label', default: '${className}'), params.id])
        redirect(action: "list")
        return
    }
    [...]

and the scaffolded controller code (which is not called, while I believe it should):

class CalendarController {
    static scaffold = Calendar

    def beforeUpdate = {
            println "beforeUpdate from controller"
    }
}

I have already tried grails clean ;-)

UPDATE

I have eventually realized that this is simply impossibile due to how the Grails scaffolding is designed. Closing.

Answer 1

I have eventually realized that this is simply impossibile due to how the Grails scaffolding is designed: by dynamically copying/creating methods into the scaffolded controllers and not using inheritance.

Answer 2

You have a similar problem to this question - essentially the way scaffolding works the scaffolding template generates a separate class which the "real" controller delegates to. So if you want the generated controller to call methods on the real controller you can't use this, you need to get a reference to the real controller object.

To cut a long story short, use

GrailsWebUtil.getControllerFromRequest(request).beforeUpdate()

instead of just

beforeUpdate()

---

def update() {
    // call before update hook
    def realController = GrailsWebUtil.getControllerFromRequest(request)
    if(realController.hasProperty('beforeUpdate') &&
         realController.beforeUpdate instanceof Closure) {
      realController.beforeUpdate()
    } else {
      this.beforeUpdate()
    }

    def ${propertyName} = ${className}.get(params.id)
    if (!${propertyName}) {
        flash.message = message(code: 'default.not.found.message', args: [message(code: '${domainClass.propertyName}.label', default: '${className}'), params.id])
        redirect(action: "list")
        return
    }
    [...]