Hmm, it's been a bit since I did a flow, and your example is simplistic (just for being an example's sake, I hope).
What your missing is the initial action in the flow. Keep in mind that a "view" flow action as your showProducts is just says what to do when your showProducts gsp POSTS. It's the action that SENT you to showProducts that should create the model to be used in showProducts.gsp
def ShoppingCartFlow = {
initialize {
action { // note this is an ACTION flow task
// perform some code
[ model: modelInstance ] // this model will be used in showProducts.gsp
}
on ("success").to "showProducts"
// it's the above line that sends you to showProducts.gsp
}
showProducts {
// note lack of action{} means this is a VIEW flow task
// you'll get here when you click an action button from showProducts.gsp
on("checkout").to "enterPersonalDetails"
on("continueShopping").to "displayCatalogue"
}
// etc. (you'll need an enterPersonalDetails task,
// displayCatalogue task, and they
// should both be ACTION tasks)
}
Make sense?