自定义校验

type CreateTransferRequest struct {
		FromAccountID int64  `json:"fromAccountID" binding:"required"`
		ToAccountID   int64  `json:"toAccountID" binding:"required"`
		Amount        int64  `json:"amount" binding:"required"`
		Currency      string `json:"currency" binding:"required,currency"`
	}

// 定义货币类型
const (
	CNY = "CNY"
	USD = "USD"
	EDR = "EDR"
)
// 校验传入的参数是否为其一
func validateCurrency(fl validate.FieldLabel) bool {
    // fl使用go映射, 需要转出需要的字段类型
	currency, ok := fl.Fileld().Interface().(string)
	switch currency {
		case CNY,USD.EDR:
		return true
	}
	return false
}

func main(){
	gin.Default()
	if validate, ok := binding.Validator.Engine().(valitor.Validate); ok {
		validate.RegisterValidation("currency", validateCurrency)
	}
}