Working with JSON in Golang: Struct Tags, Unmarshaling, and Streaming

Introduction to Go encoding/json

Golang provides high-performance JSON processing via the standard library encoding/json package.

1. Struct Tags and Unmarshaling

Define Go structs with json: tag annotations to map JSON keys:

package main

import (
    "encoding/json"
    "fmt"
)

type User struct {
    ID    int    `json:"id"`
    Name  string `json:"name"`
    Email string `json:"email,omitempty"`
}

func main() {
    jsonData := []byte(`{"id": 1, "name": "Go Developer"}`)
    var u User
    json.Unmarshal(jsonData, &u)
    fmt.Println(u.Name)
}

2. Marshaling Structs to Formatted JSON

u := User{ID: 2, Name: "Alice"}
output, _ := json.MarshalIndent(u, "", "  ")
fmt.Println(string(output))

Format and inspect Golang JSON outputs in your browser using JSON Workshop.