JSON Data Processor: Reading and Writing API Data in Go

JSON Data Processor: Reading and Writing API Data in Go

Introduction

Working with JSON is a daily task in backend development. Whether you are consuming external APIs or building your own, Go’s encoding/json package provides a robust and performant way to marshal (write) and unmarshal (read) JSON data.

1. Unmarshalling JSON (Reading)

To read JSON data, we define a struct with json tags that map the JSON keys to struct fields.

package main

import (
    "encoding/json"
    "fmt"
)

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

func main() {
    jsonData := []byte(`{"id": 1, "name": "Alice", "email": "alice@example.com"}`)

    var user User
    err := json.Unmarshal(jsonData, &user)
    if err != nil {
        fmt.Println("Error:", err)
        return
    }

    fmt.Printf("User: %+v\n", user)
}

2. Marshalling JSON (Writing)

To turn a Go struct back into JSON, we use json.Marshal or json.MarshalIndent.

func main() {
    user := User{ID: 2, Name: "Bob", Email: "bob@example.com"}

    jsonData, err := json.MarshalIndent(user, "", "  ")
    if err != nil {
        fmt.Println("Error:", err)
        return
    }

    fmt.Println(string(jsonData))
}

Conclusion

Go’s encoding/json makes data interchange simple and type-safe. By properly tagging your structs, you ensure your API responses and requests are consistently formatted, which is essential for any modern web application.

Suggested Reading

• Go Documentation: encoding/json