String

a := strconv.Itoa(12)

// ----

var id uint = 12
b := strconv.FormatUint(uint64(id), 10)

JSON

type reportRequest struct {
	...
}

json, _ := json.Marshal(reportRequest)
fmt.Println(string(json))

Int

number := "10"
int1, err := strconv.ParseInt(number, 10, 64) // string, base (decimal), size (bytes)

Quellen

How To Convert Data Types in Go | DigitalOcean