func getStateMachine() *transition.StateMachine {
var orderStateMachine = transition.New(&Order{})
orderStateMachine.Initial("draft")
orderStateMachine.State("checkout")
orderStateMachine.State("paid")
orderStateMachine.State("processed")
orderStateMachine.State("delivered")
orderStateMachine.State("cancelled")
orderStateMachine.State("paid_cancelled")
orderStateMachine.Event("checkout").To("checkout").From("draft")
orderStateMachine.Event("pay").To("paid").From("checkout")
return orderStateMachine
}
transition.Transition
}
func (order Order) Amount() (amount float32) {
for _, orderItem := range order.OrderItems {
amount += orderItem.Amount()
}
return
}
func (item OrderItem) Amount() float32 {
return item.Price * float32(item.Quantity) * float32(100-item.DiscountRate) / 100
}
var (
OrderState = transition.New(&Order{})
ItemState = transition.New(&OrderItem{})
)
func init() {
// Define Order's States
OrderState.Initial("draft")
OrderState.State("checkout")
OrderState.State("cancelled").Enter(func(value interface{}, tx *gorm.DB) error {
tx.Model(value).UpdateColumn("cancelled_at", time.Now())
return nil
})
OrderState.State("paid").Enter(func(value interface{}, tx *gorm.DB) error {
// freeze stock, change items's state
return nil
})