Decoding & validating requests

Reading the request body

A POST /bookings carries a JSON body — the walker id, the date, how long. On the server, that body is r.Body, a stream of bytes. You decode it into a Go struct with encoding/json:

type createBookingReq struct {
	WalkerID string `json:"walker_id"`
	Minutes  int    `json:"minutes"`
}

The json:"walker_id" struct tag tells the decoder which JSON key fills which field. (Tags live inside Go backticks, so you'll only ever see them in read-only snippets like this one — never type one into an exercise.)