json 接口{}到[]字节在golang中的转换
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interface{} to []byte conversion in golang
提问by kish
I am trying to unmarshal a data which is of type interface. So I need to convert the interface type to []byte and pass it to unmarshall. i tried
我正在尝试解组接口类型的数据。所以我需要将接口类型转换为 []byte 并将其传递给 unmarshall。我试过
err := json.Unmarshal([]byte(kpi), &a)=> failed- i tired to convert the interface to byte by using
kpidata, res := kpi.([]byte)=> failed, kpidata is nil
err := json.Unmarshal([]byte(kpi), &a)=> 失败- 我厌倦了使用
kpidata, res := kpi.([]byte)=>将接口转换为字节 失败，kpidata 为零
So is there any way we can convert it?
那么有什么方法可以转换它吗？
回答by matthias krull
Working example based on the one provided by Kugel:
基于 Kugel 提供的工作示例：
package main
import (
"fmt"
)
func passInterface(v interface{}) {
b, ok := v.(*[]byte)
fmt.Println(ok)
fmt.Println(b)
}
func main() {
passInterface(&[]byte{0x00, 0x01, 0x02})
}
If you do not pass references, it will work basically the same:
如果你不传递引用，它的工作原理基本相同：
回答by wasmup
In your samplecode datashould be JSON-encoded(in simple word String) so you are using Unmarshalin a wrong way:
在您的示例代码中data应该是JSON 编码的（在简单的单词String 中），所以您Unmarshal以错误的方式使用：
// Unmarshal parses the JSON-encoded data and stores the result // in the value pointed to by v. If v is nil or not a pointer, // Unmarshal returns an InvalidUnmarshalError. func Unmarshal(data []byte, v interface{}) error
// Unmarshal parses the JSON-encoded data and stores the result // in the value pointed to by v. If v is nil or not a pointer, // Unmarshal returns an InvalidUnmarshalError. func Unmarshal(data []byte, v interface{}) error
Try it on The Go Playgroundand this: []string{"art", "football"}:
尝试在旅途游乐场和这样的：[]string{"art", "football"}：
package main
import (
"encoding/json"
"fmt"
)
func main() {
// ********************* Marshal *********************
u := map[string]interface{}{}
u["name"] = "kish"
u["age"] = 28
u["work"] = "engine"
//u["hobbies"] = []string{"art", "football"}
u["hobbies"] = "art"
b, err := json.Marshal(u)
if err != nil {
panic(err)
}
fmt.Println(string(b))
// ********************* Unmarshal *********************
var a interface{}
err = json.Unmarshal(b, &a)
if err != nil {
fmt.Println("error:", err)
}
fmt.Println(a)
}
output:
输出：
{"age":28,"hobbies":"art","name":"kish","work":"engine"}
map[name:kish work:engine age:28 hobbies:art]
You want to Unmarshalit, so try thissimple working example ([]byte(kpi.(string)):
你想解组它，所以试试这个简单的工作示例 ( []byte(kpi.(string))：
package main
import (
"encoding/json"
"fmt"
)
func main() {
var kpi interface{} = st
var a []Animal
err := json.Unmarshal([]byte(kpi.(string)), &a)
if err != nil {
fmt.Println("error:", err)
}
fmt.Println(a)
}
type Animal struct {
Name string
Order string
}
var st = `[
{"Name": "Platypus", "Order": "Monotremata"},
{"Name": "Quoll", "Order": "Dasyuromorphia"}
]`
output:
输出：
[{Platypus Monotremata} {Quoll Dasyuromorphia}]
Working exampleusing ([]byte(*kpi.(*string))):
使用 ( ) 的工作示例[]byte(*kpi.(*string))：
package main
import (
"encoding/json"
"fmt"
)
func main() {
var kpi interface{} = &st
var a []Animal
err := json.Unmarshal([]byte(*kpi.(*string)), &a)
if err != nil {
fmt.Println("error:", err)
}
fmt.Println(a)
}
type Animal struct {
Name string
Order string
}
var st = `[
{"Name": "Platypus", "Order": "Monotremata"},
{"Name": "Quoll", "Order": "Dasyuromorphia"}
]`
元帅：
package main
import (
"encoding/json"
"fmt"
)
func main() {
u := map[string]interface{}{}
u["1"] = "one"
b, err := json.Marshal(u)
if err != nil {
panic(err)
}
fmt.Println(string(b))
}
output:
输出：
{"1":"one"}
I hope this helps.
我希望这有帮助。
