E0405: A handler parameter can't be bound

A hook's or handler's parameters are filled by type: context.Context, *http.Request, one struct (or url.Values) from the request's body or form — on a live page, the event's form —, scalars from the path or query (on a live page, the event's value), and types the app provides. This parameter is none of them: a type a request can't carry (chan int), a second struct, a second value from a live event, a hook's parameter that isn't the context or a provided type, or, in a handler registered from Go, a scalar with no path segment left to bind (reflection can't see names: Go takes the query in a struct). Reported at boot, at the handler's file and line, and by vukavet.

Wrong

@web.Post("/pets")
func AddPet(p Pet, owner Owner) Result[Pet] { … }

func SearchPets(q string, store *PetStore) ([]Pet, error) { return store.Search(q) }

func init() {
	web.Routes.Get("/pets", SearchPets) // q has no name and no segment: reflection can't see it
}

Right

@web.Post("/pets")
func AddPet(p Pet, owners *Owners) Result[Pet] { … }

type Search struct {
	Q string `form:"q"`
}

func SearchPets(s Search, store *PetStore) ([]Pet, error) { return store.Search(s.Q) }

func init() {
	web.Routes.Get("/pets", SearchPets)
}