omitempty

忽略 struct 空字段，当字段的值为空值的时候，它不会出现在JSON数据中.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20

package main

import (
    "encoding/json"
    "fmt"
)

type User struct {
    Email    string `json:"email"`
    Password string `json:"password,omitempty"`
}

func main() {
    jsonByte, _ := json.Marshal(User{Email: "7@qq.com"})
    fmt.Println(string(jsonByte))
}

// 输出结果
// 不带 omitempty 的输出结果：{"email":"7@qq.com","password":""}
// 带 omitempty 的输出结果：{"email":"7@qq.com"}

临时合并两个struct

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30

package main

import (
    "encoding/json"
    "fmt"
)

func main() {
    type BlogPost struct {
        URL   string `json:"url"`
        Title string `json:"title"`
    }
    type Analytics struct {
        Visitors  int `json:"visitors"`
        PageViews int `json:"page_views"`
    }

    blog := BlogPost{URL: "http://www.x.com", Title: "title"}
    analytics := Analytics{Visitors: 100, PageViews: 200}

    jsonByte, _ := json.Marshal(struct {
        *BlogPost
        *Analytics
    }{&blog, &analytics})

    fmt.Println(string(jsonByte))

    // 输出结果
    // {"url":"http://www.x.com","title":"title","visitors":100,"page_views":200}
}

一个json切分成两个struct

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34

package main

import (
    "encoding/json"
    "fmt"
)

func main() {
    type BlogPost struct {
        URL   string `json:"url"`
        Title string `json:"title"`
    }
    type Analytics struct {
        Visitors  int `json:"visitors"`
        PageViews int `json:"page_views"`
    }

    var (
        blog      BlogPost
        analytics Analytics
    )

    json.Unmarshal([]byte(`{"url":"http://www.x.com","title":"title","visitors":100,"page_views":200}`), &struct {
       *BlogPost
       *Analytics
    }{&blog, &analytics})

    fmt.Println(blog)
    fmt.Println(analytics)

    // 输出结果
    // {http://www.x.com title}
    // {100 200}
}

数字以字符串形式输出

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19

package main

import (
    "encoding/json"
    "fmt"
)

type Test struct {
    Email string `json:"email"`
    Field int    `json:"field,string"`
}

func main() {
    jsonByte, _ := json.Marshal(Test{Email: "7@qq.com", Field: 100})
    fmt.Println(string(jsonByte))
}

// 输出结果
// {"email":"7@qq.com","field":"100"}

json和map转换

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18

func main() {
    jsonStr := `
        {
          "env": "local",
          "redis_address": "127.0.0.1:6379",
          "redis_password": "xxx"
        }
    `

    // json转换成map
    m := make(map[string]interface{})
    _ = json.Unmarshal([]byte(jsonStr), &m)
    fmt.Println(m) // 输出：map[env:local redis_address:127.0.0.1:6379 redis_password:xxx]

    // map转换成json
    j, _ := json.Marshal(m)
    fmt.Println(string(j)) // 输出：{"env":"local","redis_address":"127.0.0.1:6379","redis_password":"xxx"}
}