原文地址:https://www.douyacun.com/article/3d297fcf96895f61035407e5612cd7ed
omitempty
字段为空时( 空指针, 空接口, 空数组, slice, map, or string.),json encode时不返回该字段type person struct {
Name string `json:"name,omitempty"`
Age int `json:"age"`
}
var p = person{
Name: "",
Age: 18,
}
if res, err := json.Marshal(&p); err != nil {
fmt.Println(err)
return
} else {
fmt.Println(string(res))
}
// {"age":18}
string
字符串和数字类型转换,对于php和js这类弱类型语言字符串和数字很容易就混type person struct {
Name string `json:"name,omitempty"`
Age int `json:"age,string"`
}
var p1 person
str := `{"name":"douyacun", "age": "18"}`
if err := json.Unmarshal([]byte(str), &p1); err != nil {
fmt.Println(err)
return
}
fmt.Println(p1)
// {douyacun 18}
如果age 没有string tag的话,会报错 json: cannot unmarshal string into Go struct field person.age of type int
-
忽略字段type person struct {
Name string `json:"name,omitempty"`
Age int `json:"age,string"`
Height int `json:"-"`
}
var p = person{
Name: "",
Age: 18,
Height: 180,
}
if res, err := json.Marshal(&p); err != nil {
fmt.Println(err)
return
} else {
fmt.Println(string(res))
}
// {"age":"18"}
var p1 person
str := `{"name":"douyacun", "age": "18", "height": 180}`
if err := json.Unmarshal([]byte(str), &p1); err != nil {
fmt.Println(err)
return
}
fmt.Println(p1)
// {douyacun 18 0}
fmt.Println(json.Valid([]byte(`{"name":"douyacun", "age": "18", "height": 180}`)))
// true
var jsonStream = `
{"Message": "Hello", "Array": [1, 2, 3], "Null": null, "Number": 1.234}
`
des := json.NewDecoder(strings.NewReader(jsonStream))
for{
t, err := des.Token()
if err == io.EOF {
break
}
if err != nil {
fmt.Printf("%v\n", err)
return
}
if _, ok := t.(json.Delim); !ok {
fmt.Printf("%T: %v\n", t, t)
}
}
// string: Hello
// string: Array
// float64: 1
// float64: 2
// float64: 3
// string: Null
// <nil>: <nil>
// string: Number
// float64: 1.234
type person struct {
Weight json.Number `json:"weight"`
}
var p person
str := `{"weight": 19}`
if err := json.Unmarshal([]byte(str), &p); err != nil {
fmt.Println(err)
return
}
fmt.Println(p.Weight.Int64())
// 19 <nil>
编码
type person struct {
Weight json.Number `json:"weight"`
Skill json.RawMessage `json:"skill"`
}
skill := map[string]interface{}{
"language": []string{"c", "php", "js", "golang"},
"js": []string{"react"},
"php": []string{"Laravel", "ThinkPHP"},
"golang": []string{"gin"},
}
res, err := json.Marshal(skill)
if err != nil {
fmt.Println(err)
}
p := person{
Weight: "89",
Skill: json.RawMessage(res),
}
if res, err := json.MarshalIndent(p, "", "\t"); err != nil {
fmt.Println(err)
return
} else {
fmt.Println(string(res))
}
输出
{
"weight": 89,
"skill": {
"golang": [
"gin"
],
"js": [
"react"
],
"language": [
"c",
"php",
"js",
"golang"
],
"php": [
"Laravel",
"ThinkPHP"
]
}
}
解码
像ES search结果集,外层有公共的数据结构
{
"took" : 0,
"timed_out" : false,
"_shards" : {
"total" : 1,
"successful" : 1,
"skipped" : 0,
"failed" : 0
},
"hits" : {
"total" : {
"value" : 12,
"relation" : "eq"
},
"max_score" : 1.0,
"hits" : []
}
}
fmt.Println(p1)
// {douyacun 18}
// 如何不加string,会报错: json: cannot unmarshal string into Go struct field person.age of type int
结构体
type ESListResponse struct {
Took int `json:"took"`
Timeout bool `json:"timed_out"`
Shards struct {
Total int `json:"total"`
Successful int `json:"successful"`
Skipped int `json:"skipped"`
Failed int `json:"failed"`
} `json:"_shards"`
Hits struct {
Total struct {
Value int `json:"value"`
Relation string `json:"relation"`
} `json:"total"`
MaxScore float64 `json:"max_score"`
Hits []json.RawMessage `json:"hits"`
} `json:"hits"`
}
type ESItemResponse struct {
Index string `json:"_index"`
Type string `json:"_type"`
Id string `json:"_id"`
Score float64 `json:"_score"`
Source json.RawMessage `json:"_source"`
}
这个有点复杂,写个简单的例子:
type person struct {
Weight json.Number `json:"weight"`
Skill json.RawMessage `json:"skill"`
}
str := `{
"weight": 180,
"skill": {
"language": ["php", "golang", "c", "python"],
"database": ["elasticsearch", "mysql", "redis"]
}
}`
var p person
if err := json.Unmarshal([]byte(str), &p); err != nil {
fmt.Println(err)
return
}
fmt.Printf("weight: %s\nskill: %s\n", p.Weight, p.Skill)
type _skill struct {
Language []string `json:"language"`
Database []string `json:"database"`
}
var skill _skill
if err := json.Unmarshal(p.Skill, &skill); err != nil {
fmt.Println(err)
return
}
fmt.Printf("%+v\n", skill)
输出:
weight: 180
skill: {
"language": ["php", "golang", "c", "python"],
"database": ["elasticsearch", "mysql", "redis"]
}
{Language:[php golang c python] Database:[elasticsearch mysql redis]}
其实 p.Skill 还是 []byte,可以再次被 Unmarshal