Scope of form variables in Grails

Question

Hi,

I am creating a Grails application which has an input page with text fields. Here the user can type in the data and on submit, the control goes to the action in controller. Here I get the value of the form data using params.empName etc.

But the scope of this data is very small and doesnt get carried on if I do a redirect from the current action to another action.

Is there a way to increase the scope of the variables?

I am now to convert this to service oriented architecture. Therefore Is there a way to access these data in the service as well?

Please advice.

Thanks, Megs

Answer 1

You can add...

params: params

...as an argument to the redirect, so that the incoming params are sent along with the redirect.

Answer 2

I don't think there's a built-in way to increase the scope. This is probably a Good Thing.

If you're redirecting in controllers, you should simply pass along the necessary parameters via the redirect() params dynamic property. Example:

def formHandler = {
    // do stuff with params
    redirect(action: 'anotherAction', params: params)
}

If you need scope to span multiple requests, e.g. if you're having a multi-step form entry given to the user, you might look into using web flows to persist state between requests.

For services, you're better off just passing down what you need as arguments to the service method, rather than exposing params. Example (similar to the Accessing Services section here):

// service
def myServiceMethod(def foo, def bar) {
    // do stuff
}

// controller
def myService
def myControllerAction {
    myService.myServiceMethod(params.foo, params.bar)
}

Exposing parameters from the controller to the service layer would break the layer-oriented approach Grails is trying to provide you; i.e. the "model" and "controller" components (of MVC) would be more tightly coupled.

Answer 3

I would also take a look at chaining actions as a way to pass the model information

http://www.grails.org/Controllers+-+Redirects