Example (Go) - Structs and .json

// go.mod
module example.com/note

go 1.22.0

// main.go
package main

import (
	"bufio"
	"fmt"
	"os"
	"strings"

	"example.com/note/note"
)

func main() {
	title, content := getNoteData()

	note, err := note.New(title, content)
	if err != nil {
		fmt.Println("Error:", err)
        return
	}

	note.Display()
    result := note.Save()
    if result != nil {
        panic("Error saving note.")
    }

    println("Note saved successfully!")
}

func getNoteData() (string, string) {
	title := getUserInput("Note title: ")
	content := getUserInput("Note content: ")
	return title, content
}

func getUserInput(prompt string) string {
	fmt.Print(prompt)

	// var value string
	// ====Scanln only works for single word inputs====
	// fmt.Scanln(&value)

	reader := bufio.NewReader(os.Stdin)
	text, err := reader.ReadString('\n') //! Read until this. We are using single quote as it refers to a byte type
	if err != nil {
		return ""
	}

	text = strings.TrimSuffix(text, "\n")
	text = strings.TrimSuffix(text, "\r") //! For windows users
	return text
}

package note

import (
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"strings"
	"time"
)

type Note struct {
	Title     string `json:"title"`
	Content   string `json:"content"`
	CreatedAt time.Time `json:"created_at"`
}

func New(title, content string) (Note, error) {
	if title == "" || content == "" {
		return Note{}, errors.New("Invalid input.")
	}

	return Note{
		Title:     title,
		Content:   content,
		CreatedAt: time.Now(),
	}, nil
}

func (note Note) Display() {
    fmt.Println("Your note titled:", note.Title, "was created at", note.CreatedAt)
    fmt.Println("Contains: ", note.Content)
}

func (note Note) Save() (error) {
    fileName := strings.ReplaceAll(note.Title, " ", "_")
    fileName = strings.ToLower(fileName) + ".json"
    
    json, err := json.Marshal(note) //! Only works on structs with all fields public
    if err != nil {
        return err
    }

    return os.WriteFile(fileName, json, 0644)
}