json
最后更新于：2022-04-02 02:43:33
[TOC]
## 标识符
### omitempty 为空不显示
添加`omitempty`后,如果 data 为空,则不显示 data
如 0 ,"",flase 等都为空值
```
type H struct{
Msg string `json:"msg"`
Data interface{} `json:"data,omitempty"`
}
```
`{"name":"asd"}`
### - 过滤都该字段的序列化
```
type H struct{
Msg string `json:"msg"`
Data interface{} `json:"-"`
}
```
`{"name":"asd"}`
### 指定序列化格式,可让 int 转为 string
```
type User struct {
Name string `json:"name"`
Age int8 `json:"age,string"`
}
```
`{"name":"asd","age":"123"}`
## json.Marshal
```
type ColorGroup struct {
ID int
Name string
Colors []string
}
group := ColorGroup{
ID: 1,
Name: "Reds",
Colors: []string{"Crimson", "Red", "Ruby", "Maroon"},
}
b, err := json.Marshal(group)
if err != nil {
fmt.Println("error:", err)
}
fmt.Printf("%+v\n", string(b))
// {"ID":1,"Name":"Reds","Colors":["Crimson","Red","Ruby","Maroon"]}
```
## json.Unmarshal
```
var jsonBlob = []byte(`[
{"Name": "Platypus", "Order": "Monotremata"},
{"Name": "Quoll", "Order": "Dasyuromorphia"}
]`)
type Animal struct {
Name string
Order string
}
var animals []Animal
err := json.Unmarshal(jsonBlob, &animals)
if err != nil {
fmt.Println("error:", err)
}
fmt.Printf("%+v", animals)
// [{Name:Platypus Order:Monotremata} {Name:Quoll Order:Dasyuromorphia}]
```
### json.Indent 缩进json
```
var jsonBlob = []byte(`[
{"Name": "Platypus", "Order": "Monotremata"},
{"Name": "Quoll", "Order": "Dasyuromorphia"}
]`)
var a bytes.Buffer
err := json.Indent(&a, jsonBlob, "", " ")
if err != nil {
panic(err)
}
fmt.Printf("%+v\n", a.String())
/*
[
{
"Name": "Platypus",
"Order": "Monotremata"
},
{
"Name": "Quoll",
"Order": "Dasyuromorphia"
}
]
*/
```
## json.HTMLEscape
```
var out bytes.Buffer
json.HTMLEscape(&out, []byte(`{"Name":"HTML content"}`))
out.WriteTo(os.Stdout)
// Output:
//{"Name":"\u003cb\u003eHTML content\u003c/b\u003e"}
```
## json.NewDecoder 有杂质信息也可序列化
```
type User struct {
UserName string `json:"username"`
Password string `json:"password"`
}
jsonString := `{
"username": "foobar@example.com",
"password": "YOUR PASSWORD"
}otherinfo`
str := strings.NewReader(jsonString) // io.Reader
usr := User{}
err := json.NewDecoder(str).Decode(&usr)
if err != nil {
log.Fatalf("Decode failed, %#v\n", err)
}
log.Printf("User %#v\n", usr)//User main.User{UserName:"foobar@example.com", Password:"YOUR PASSWORD"}
```
';