encoding/json

JSON — ma’lumot almashishning eng keng tarqalgan formati. Go ning encoding/json paketi struct’lar bilan JSON o’rtasida tabiiy aylantirish beradi.

Marshal — struct’dan JSON’ga

json.Marshal Go qiymatini JSON baytlariga aylantiradi. Faqat eksport qilingan (bosh harfli) maydonlar JSON’ga tushadi.

package main
 
import (
    "encoding/json"
    "fmt"
)
 
type User struct {
    Name string
    Age  int
}
 
func main() {
    data, _ := json.Marshal(User{Name: "Ali", Age: 27})
    fmt.Println(string(data))
}

$ go run marshal.go
{"Name":"Ali","Age":27}

Takeaway: kichik harfli (eksport qilinmagan) maydonlar JSON’da ko’rinmaydi.

Manba / batafsil: pkg.go.dev/encoding/json#Marshal 

Struct tag’lar va omitempty

json:"..." tag’i JSON kalitini belgilaydi. omitempty bo’sh (nol) qiymatni tashlab yuboradi, - esa maydonni butunlay chiqarib tashlaydi.

package main
 
import (
    "encoding/json"
    "fmt"
)
 
type User struct {
    Name     string `json:"name"`
    Nickname string `json:"nickname,omitempty"`
    Password string `json:"-"`
}
 
func main() {
    data, _ := json.Marshal(User{Name: "Ali", Password: "maxfiy"})
    fmt.Println(string(data))
}

$ go run tags.go
{"name":"Ali"}

Takeaway: maxfiy maydonlarga json:"-", ixtiyoriylarga omitempty qo’ying.

Manba / batafsil: pkg.go.dev/encoding/json#Marshal (tags) 

MarshalIndent

Odam o’qishi uchun chekinishli (indented) JSON kerak bo’lsa MarshalIndent ishlatiladi: prefiks va chekinish belgisini beradi.

package main
 
import (
    "encoding/json"
    "fmt"
)
 
func main() {
    p := map[string]any{"name": "Klaviatura", "price": 49.99}
    data, _ := json.MarshalIndent(p, "", "  ")
    fmt.Println(string(data))
}

$ go run indent.go
{
  "name": "Klaviatura",
  "price": 49.99
}

Takeaway: log va config fayllar uchun MarshalIndent, tarmoq uchun oddiy Marshal.

Manba / batafsil: pkg.go.dev/encoding/json#MarshalIndent 

Unmarshal va map’ga o’qish

json.Unmarshal JSON’ni struct’ga o’qiydi (pointer berish shart). Tuzilma noma’lum bo’lsa map[string]any ga o’qiladi — bunda barcha sonlar float64 bo’lib keladi.

package main
 
import (
    "encoding/json"
    "fmt"
)
 
func main() {
    var m map[string]any
    json.Unmarshal([]byte(`{"name":"Laptop","price":1200}`), &m)
    fmt.Println(m["name"])
    fmt.Printf("%v (%T)\n", m["price"], m["price"])
}

$ go run unmarshal.go
Laptop
1200 (float64)

Takeaway: map[string]any da JSON sonlari doim float64 — tez-tez chalkashtiradigan nuqta.

Manba / batafsil: pkg.go.dev/encoding/json#Unmarshal 

Encoder va Decoder — oqim bilan

Fayl yoki tarmoq oqimlari uchun NewEncoder/NewDecoder qulayroq: ular io.Writer/io.Reader bilan to’g’ridan-to’g’ri ishlaydi. HTTP handler’larda aynan shular ishlatiladi.

package main
 
import (
    "encoding/json"
    "os"
)
 
type Task struct {
    ID    int    `json:"id"`
    Title string `json:"title"`
}
 
func main() {
    enc := json.NewEncoder(os.Stdout)
    enc.SetIndent("", "  ")
    enc.Encode(Task{ID: 1, Title: "JSON o'rganish"})
}

$ go run stream.go
{
  "id": 1,
  "title": "JSON o'rganish"
}

Takeaway: Encode har chaqiruvda oxiriga yangi qator qo’shadi; oqimlarda xotira tejaydi.

Manba / batafsil: pkg.go.dev/encoding/json#NewEncoder 

Keyingi qismda net/http bilan HTTP server yozamiz.