The JSON string is parsed to the struct

Code example

type User struct {
 Name      string
 FansCount int64
}

// 如果反序列化的时候指定明确的结构体和变量类型
func TestJsonUnmarshal(t *testing.T) {
 const jsonStream = `
        {"name":"ethancai", "fansCount": 9223372036854775807}
    `
 var user User // 类型为User
 err := JsonUnmarshal(jsonStream, &user)
 if err != nil {
  fmt.Println("error:", err)
 }
 fmt.Printf("%+v \n", user)
}

Parsing Json arrays to slices (arrays)

type Person struct {
 Name string
 Age  int
}

type Family struct {
 Persons []Person
}

// 解析多维数组
var f Family

// 模拟传输的Json数据
familyJSON := `{"Persons": [{"Name":"Elinx","Age":26}, {"Name":"Twinkle","Age":21}] }`

fmt.Println("======================")

// 解析字符串为Json
json.Unmarshal([]byte(familyJSON), &f)

Run the result

=== RUN   TestJsonMash
======================
{[{Elinx 26 0001-01-01 00:00:00 +0000 UTC []} {Twinkle 21 0001-01-01 00:00:00 +0000 UTC []}]}
{"Persons":[{"Name":"Elinx","Age":26,"Birth":"0001-01-01T00:00:00Z","Children":null}
--- PASS: TestJsonMash (0.00s)
PASS

Use the struct tag to assist in building json

The fields that struct can be converted are all fields with uppercase initials, but if you want to use a key beginning with a lowercase letter in json, you can use the struttag to assist in reflection.

type Post struct {
 Id      int      `json:"ID"`
 Content string   `json:"content"`
 Author  string   `json:"author"`
 Label   []string `json:"label"`
}
func TestJsonMash1(t *testing.T){
 postp := &Post{
  2,
  "Hello World",
  "userB",
  []string{"linux", "shell"},
 }

 p, _ := json.MarshalIndent(postp, "", "\t")
 fmt.Println(string(p))
}

Running result:

=== RUN   TestJsonMash1
{
 "ID": 2,
 "content": "Hello World",
 "author": "userB",
 "label": [
  "linux",
  "shell"
 ]
}
--- PASS: TestJsonMash1 (0.00s)
PASS

How to use tags

The name identified in the tag will be called the value of the key in the json data
Tag can be set to json: "-" to indicate that this field is not converted to json data, even if the field's initials are capitalized
If you want the name of the json key to be the character "-", you can specially treat json: "-,", that is, add a comma
If the tag has the omitempty option, then if the value of this field is 0 values, i.e. false, 0, "", nil, etc., this field will not be converted to json
If the type of the field is bool, string, int class, float class, and the tag has the string option, then the value of the field will be converted to a json string

Parses Json data into a structure known to struct

{
    "id": 1,
    "content": "hello world",
    "author": {
        "id": 2,
        "name": "userA"
    },
    "published": true,
    "label": [],
    "nextPost": null,
    "comments": [{
            "id": 3,
            "content": "good post1",
            "author": "userB"
        },
        {
            "id": 4,
            "content": "good post2",
            "author": "userC"
        }
    ]
}

Test the code

type Post struct {
 ID        int64         `json:"id"`
 Content   string        `json:"content"`
 Author    Author        `json:"author"`
 Published bool          `json:"published"`
 Label     []string      `json:"label"`
 NextPost  *Post         `json:"nextPost"`
 Comments  []*Comment    `json:"comments"`
}

type Author struct {
 ID   int64  `json:"id"`
 Name string `json:"name"`
}

type Comment struct {
 ID      int64  `json:"id"`
 Content string `json:"content"`
 Author  string `json:"author"`
}

func TestJsonStruct(t *testing.T){
 jsonData :="{\n    \"id\": 1,\n    \"content\": \"hello world\",\n    \"author\": {\n        \"id\": 2,\n        \"name\": \"userA\"\n    },\n    \"published\": true,\n    \"label\": [],\n    \"nextPost\": null,\n    \"comments\": [{\n            \"id\": 3,\n            \"content\": \"good post1\",\n            \"author\": \"userB\"\n        },\n        {\n            \"id\": 4,\n            \"content\": \"good post2\",\n            \"author\": \"userC\"\n        }\n    ]\n}"
 var post Post
 // 解析json数据到post中
 err := json.Unmarshal([]byte(jsonData), &post)
 if err != nil {
  fmt.Println(err)
  return
 }
 fmt.Println(post)
 fmt.Println(post.Author, post.Content, post.Comments[0].Content,post.Comments[0].ID, post.Comments[0].Author )
}

=== RUN   TestJsonStruct
{1 hello world {2 userA} true [] <nil> [0xc00016d1a0 0xc00016d1d0]}
{2 userA} hello world good post1 3 userB
--- PASS: TestJsonStruct (0.00s)
PASS

Welcome to pay attention to the public account: The Road to Freedom of Programmer Wealth

Insert a description of the image here

Resources

https://www.cnblogs.com/f-ck-need-u/p/10080793.html

Go language JSON processing