Is this status change allowed
Orders move through a fixed lifecycle, and a support tool needs to know whether a requested change is one the system permits.
- The only moves allowed are: placed to paid, placed to cancelled, paid to packed, paid to refunded, packed to shipped, shipped to delivered.
- Everything else is refused, including staying where you are.
- Unknown status names are refused.
canTransition(current: string, target: string) → bool
Go needs a compiler and Drill does not host one yet, so this page is the reference rather than an exercise: the problem, worked examples, and the solution in full. To type it out, the same problem runs in Python.
Where you start
func canTransition(current string, target string) bool {
}Worked examples
| Call | Result |
|---|---|
canTransition("placed", "paid") | true |
canTransition("paid", "refunded") | true |
canTransition("shipped", "delivered") | true |
canTransition("placed", "shipped") | false |
Hint
A set of allowed pairs is easier to get right than a nest of ifs.
Reference solution in Go
func canTransition(current string, target string) bool {
allowed := map[string]bool{
"placed>paid": true, "placed>cancelled": true, "paid>packed": true,
"paid>refunded": true, "packed>shipped": true, "shipped>delivered": true,
}
return allowed[current+">"+target]
}