本篇文章說明 encoding/json 部分函式，JSON 和 byte[] 轉換，還有透過 map 只轉換特定屬性

Official Document

struct 轉換 JSON (Marshal)

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func Marshal(v any) ([]byte, error)
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type Person struct {
    ID     int
    Name   string
}

person := Person{
    ID:     1,
    Name:   "Bob",
}
jsonBlob, _ := json.Marshal(person)
os.Stdout.Write(jsonBlob) // {"ID":1,"Name":"Bob"}

JSON 轉換 struct (Unmarshal)

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func Unmarshal(data []byte, v any) error
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type Person struct {
    ID    int
    Name  string
}

var jsonBlob = []byte(`{"id": 1, "name": "Bob"}`)
var person Person
json.Unmarshal(jsonBlob, &person)
fmt.Printf("%+v", person) // {ID:1 Name:Bob}

JSON 轉換指定屬性 struct

使用 map 處理這個功能

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func Unmarshal(data []byte, v any) error

type Name struct {
    First  string
    Last   string
}

type Person struct {
    ID    int
    Name  Name
}

var jsonBlob = []byte(`{"ID": 1, "Name": { "First": "Chen", "Last": "Bob" }}`)
var obj map[string]json.RawMessage
var name Name
json.Unmarshal(jsonBlob, &obj)
json.Unmarshal(obj["Name"], &name)
fmt.Printf("%+v", name) // {First:Chen Last:Bob}

json/struct 屬性對應

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type Person struct {
    ID     int    `json:"id"`
    Name   string `json:"name"`
}
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person := Person{
    ID:     1,
    Name:   "Bob",
}
jsonBlob, _ := json.Marshal(person)
os.Stdout.Write(jsonBlob) // {"id":1,"name":"Bob"}
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var jsonBlob = []byte(`{"id": 1, "name": "Bob"}`)
var person Person
json.Unmarshal(jsonBlob, &person)
fmt.Printf("%+v", person) // {ID:1 Name:Bob}

只取需要屬性

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type Person struct {
    Name   string `json:"name"`
}

var jsonBlob = []byte(`{"id": 1, "name": "Bob"}`)
var person Person
json.Unmarshal(jsonBlob, &person)
fmt.Printf("%+v", person) // {Name:Bob}