英文:
How to marshal a byte/uint8 array as json array in Go?
问题
我有一个包含[]uint8成员的结构体，并且我正在使用json.Marshal将其写入。问题是，它将uint8解释为char，并输出一个字符串而不是一个数字数组。
如果是[]int，我可以使其工作，但是如果可以避免的话，我不想分配和复制项目。我能做到吗？
英文:
I've got a struct with a []uint8 member and I'm writing it with json.Marshal. Trouble is, it's interpreting the uint8s as chars and it outputs a string rather than an array of numbers.
I can get this to work if it's a []int, but I don't want to have to allocate and copy over the items if I can avoid it. Can I?
答案1
得分: 28
根据文档，[]byte将被编码为Base64字符串。
“数组和切片值被编码为JSON数组，除了[]byte被编码为Base64编码的字符串，nil切片被编码为null JSON对象。”
所以我认为你可能需要让你的结构体实现Marshaler接口，通过实现自己的MarshalJSON方法，将[]uint8编码为更理想的JSON数组。
以这个例子为例：
import "fmt"import "encoding/json"import "strings"type Test struct {Name stringArray []uint8}func (t *Test) MarshalJSON() ([]byte, error) {var array stringif t.Array == nil {array = "null"} else {array = strings.Join(strings.Fields(fmt.Sprintf("%d", t.Array)), ",")}jsonResult := fmt.Sprintf(`{"Name":%q,"Array":%s}`, t.Name, array)return []byte(jsonResult), nil}func main() {t := &Test{"Go", []uint8{'h', 'e', 'l', 'l', 'o'}}m, err := json.Marshal(t)if err != nil {fmt.Println(err)}fmt.Printf("%s", m) // {"Name":"Go","Array":[104,101,108,108,111]}}
http://play.golang.org/p/Tip59Z9gqs
或者也许更好的想法是创建一个新类型，将[]uint8作为其底层类型，将该类型设为Marshaler，并在你的结构体中使用该类型。
import "fmt"import "encoding/json"import "strings"type JSONableSlice []uint8func (u JSONableSlice) MarshalJSON() ([]byte, error) {var result stringif u == nil {result = "null"} else {result = strings.Join(strings.Fields(fmt.Sprintf("%d", u)), ",")}return []byte(result), nil}type Test struct {Name stringArray JSONableSlice}func main() {t := &Test{"Go", []uint8{'h', 'e', 'l', 'l', 'o'}}m, err := json.Marshal(t)if err != nil {fmt.Println(err)}fmt.Printf("%s", m) // {"Name":"Go","Array":[104,101,108,108,111]}}
http://play.golang.org/p/6aURXw8P5d
英文:
According to the docs, a []byte will be encoded as a Base64 string.
>"Array and slice values encode as JSON arrays, except that []byte encodes as a base64-encoded string, and a nil slice encodes as the null JSON object."
So I think that you may need to make your struct implement the Marshaler interface by implementing your own MarshalJSON method that makes a more desirable JSON array encoding out of your []uint8.
Take this example:
import "fmt"import "encoding/json"import "strings"type Test struct {Name stringArray []uint8}func (t *Test) MarshalJSON() ([]byte, error) {var array stringif t.Array == nil {array = "null"} else {array = strings.Join(strings.Fields(fmt.Sprintf("%d", t.Array)), ",")}jsonResult := fmt.Sprintf(`{"Name":%q,"Array":%s}`, t.Name, array)return []byte(jsonResult), nil}func main() {t := &Test{"Go", []uint8{'h', 'e', 'l', 'l', 'o'}}m, err := json.Marshal(t)if err != nil {fmt.Println(err)}fmt.Printf("%s", m) // {"Name":"Go","Array":[104,101,108,108,111]}}
http://play.golang.org/p/Tip59Z9gqs
Or maybe a better idea would be to make a new type that has []uint8 as its underlying type, make that type a Marshaler, and use that type in your struct.
import "fmt"import "encoding/json"import "strings"type JSONableSlice []uint8func (u JSONableSlice) MarshalJSON() ([]byte, error) {var result stringif u == nil {result = "null"} else {result = strings.Join(strings.Fields(fmt.Sprintf("%d", u)), ",")}return []byte(result), nil}type Test struct {Name stringArray JSONableSlice}func main() {t := &Test{"Go", []uint8{'h', 'e', 'l', 'l', 'o'}}m, err := json.Marshal(t)if err != nil {fmt.Println(err)}fmt.Printf("%s", m) // {"Name":"Go","Array":[104,101,108,108,111]}}
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