How to Convert Between JSON and Structs Using Code Generators

Go does not have a built-in code generator to convert between JSON and structs; you must use the encoding/json package to marshal and unmarshal data manually. Define your struct with JSON tags to map fields, then use json.Unmarshal to convert JSON bytes to the struct and json.Marshal to convert the struct back to JSON bytes.

package main

import (
	"encoding/json"
	"fmt"
)

type User struct {
	Name string `json:"name"`
	Age  int    `json:"age"`
}

func main() {
	jsonStr := `{"name":"Alice","age":30}`
	var u User
	if err := json.Unmarshal([]byte(jsonStr), &u); err != nil {
		panic(err)
	}
	fmt.Println(u.Name) // Output: Alice

	out, _ := json.Marshal(u)
	fmt.Println(string(out)) // Output: {"name":"Alice","age":30}
}

Go does not automatically generate code to handle JSON data; instead, it provides a standard library that handles the conversion at runtime. You define a struct that matches your data shape and add special comments called tags to tell Go which JSON keys correspond to which struct fields. This is like filling out a form where you explicitly map the input fields to the database columns, rather than having a machine guess the layout for you.