如何将我的 2d 字符串切片类型转换为 []字节

Question

我已经创建了一个 2d 切片并从后端数据库填充它，但作为 json。取消封送仅接受 []byte 作为第一个参数，如何将我的 2d 切片类型转换为 []byte。

以下是示例代码供参考，因为我无法共享内部代码：

package main
import (
    "encoding/json"
    "fmt"
    "io/ioutil"
    "net/http"
)
//User sjd
type User struct {
    EmailList [][]string `json:"emailList"`
}
func listHandler(w http.ResponseWriter, r *http.Request) {
    reqBody, _ := ioutil.ReadAll(r.Body)
    var user User
    json.Unmarshal(reqBody, &user)
    el := user.EmailList 
    keys := make([][]string, 0)
    json.Unmarshal([]byte(el), &keys) //this line not working because []byte(el) not possible
    fmt.Println(keys)
    w.Header().Set("Content-Type", "application/json")
    w.WriteHeader(http.StatusOK)
    w.Write([]byte(el))//this line not working because []byte(el) not possible
}
func main() {
    http.HandleFunc("/", listHandler)
    http.ListenAndServe(":8080", nil)
}

样品请求：

{
    "emailList": [
        [
            "[e-mail]",
            "[e-mail]"
        ],
        [
            "[e-mail]",
            "[e-mail]"
        ]
    ]
}

Answer 1

Unmarshal JSON作为user []byte。 Marshal user.EmailList JSON 作为[]byte。例如

package main
import (
    "encoding/json"
    "fmt"
    "os"
)
type User struct {
    EmailList [][]string `json:"emailList"`
}
func main() {
    // rBody, err := ioutil.ReadAll(r.Body)
    rBody := []byte(`
{
    "emailList": [
        [
            "[e-mail]",
            "[e-mail]"
        ],
        [
            "[e-mail]",
            "[e-mail]"
        ]
    ]
}
    `)
    fmt.Println(string(rBody))
    var user User
    err := json.Unmarshal(rBody, &user)
    if err != nil {
        fmt.Fprintln(os.Stderr, err)
        return
    }
    fmt.Println(user.EmailList)
    wData, err := json.Marshal(user.EmailList) // wData is []byte
    if err != nil {
        fmt.Fprintln(os.Stderr, err)
        return
    }
    fmt.Println(wData) // wData is []byte
    fmt.Println(string(wData))
    // _, err = w.Write(wData)
}

游乐场：https://play.golang.org/p/S3HWiTqz--B

输出：

{
    "emailList": [
        [
            "[e-mail]",
            "[e-mail]"
        ],
        [
            "[e-mail]",
            "[e-mail]"
        ]
    ]
}
[[[e-mail] [e-mail]] [[e-mail] [e-mail]]]
[91 91 34 97 107 107 105 64 103 109 97 105 108 46 99 111 109 34 44 34 98 97 107 107 105 64 103 109 97 105 108 46 99 111 109 34 93 44 91 34 108 97 107 107 105 64 103 109 97 105 108 46 99 111 109 34 44 34 106 97 107 107 105 64 103 109 97 105 108 46 99 111 109 34 93 93]
[["[e-mail]","[e-mail]"],["[e-mail]","[e-mail]"]]