(Quick Reference)

6 Data Binding and Validation - Reference Documentation

Authors: Graeme Rocher

Version: 2.1.0

6 Data Binding and Validation

In the section on start and end states, the start state in the first example triggered a transition to the enterPersonalDetails state. This state renders a view and waits for the user to enter the required information:

enterPersonalDetails {
   on("submit").to "enterShipping"
   on("return").to "showCart"
}

The view contains a form with two submit buttons that either trigger the submit event or the return event:

<g:form>
    <!-- Other fields -->
    <g:submitButton name="submit" value="Continue"></g:submitButton>
    <g:submitButton name="return" value="Back"></g:submitButton>
</g:form>

However, what about the capturing the information submitted by the form? To capture the form info we can use a flow transition action:

enterPersonalDetails {
   on("submit") {
      flow.person = new Person(params)
      !flow.person.validate() ? error() : success()
   }.to "enterShipping"
   on("return").to "showCart"
}

Notice how we perform data binding from request parameters and place the Person instance within flow scope. Also interesting is that we perform guide:validation and invoke the error() method if validation fails. This signals to the flow that the transition should halt and return to the enterPersonalDetails view so valid entries can be entered by the user, otherwise the transition should continue and go to the enterShipping state.

Like regular actions, flow actions also support the notion of guide:commandObjects by defining the first argument of the closure:

enterPersonalDetails {
   on("submit") { PersonDetailsCommand cmd ->
       flow.personDetails = cmd
      !flow.personDetails.validate() ? error() : success()
   }.to "enterShipping"
   on("return").to "showCart"
}