データベースと Web フォームを使用して Notes アプリを構築する

package main import ( "log" ) type Note struct { ID int Title string Content string } // CreateNote adds a new note to the database func CreateNote(title, content string) { query := `INSERT INTO notes (title, content) VALUES (?, ?)` _, err := db.Exec(query, title, content) if err != nil { log.Fatal(err) } } // GetNotes retrieves all notes from the database func GetNotes() ([]Note, error) { rows, err := db.Query("SELECT id, title, content FROM notes") if err != nil { return nil, err } defer rows.Close() var notes []Note for rows.Next() { var note Note err = rows.Scan(&note.ID, &note.Title, &note.Content) if err != nil { return nil, err } notes = append(notes, note) } return notes, nil } // DeleteNote removes a note from the database func DeleteNote(id int) { query := `DELETE FROM notes WHERE id = ?` _, err := db.Exec(query, id) if err != nil { log.Fatal(err) } }

package main import ( "html/template" "log" "net/http" "strconv" ) // main function is the entry point of the program func main() { // Initialize the database initDB() // Ensure the database connection is closed when the main function exits defer db.Close() // Set up HTTP handlers for different routes http.HandleFunc("/", indexHandler) // Route for the homepage http.HandleFunc("/add", addHandler) // Route for adding a new note http.HandleFunc("/delete", deleteHandler) // Route for deleting a note // Log the server start and listen on port 8080 log.Println("Server started at :8080") log.Fatal(http.ListenAndServe(":8080", nil)) } // indexHandler handles the requests to the homepage func indexHandler(w http.ResponseWriter, r *http.Request) { // Retrieve all notes from the database notes, err := GetNotes() if err != nil { // Send an internal server error response if something goes // wrong http.Error(w, err.Error(), http.StatusInternalServerError) return } // Parse the HTML template file tmpl, err := template.ParseFiles("index.html") if err != nil { // Send an internal server error response if the template // cannot be parsed http.Error(w, err.Error(), http.StatusInternalServerError) return } // Execute the template with the notes data tmpl.Execute(w, notes) } // addHandler handles the requests to add a new note func addHandler(w http.ResponseWriter, r *http.Request) { // Only handle POST requests if r.Method == "POST" { // Get the title and content from the form values title := r.FormValue("title") content := r.FormValue("content") // Create a new note with the provided title and content CreateNote(title, content) } // Redirect the user back to the homepage after adding the note http.Redirect(w, r, "/", http.StatusSeeOther) } // deleteHandler handles the requests to delete a note func deleteHandler(w http.ResponseWriter, r *http.Request) { // Convert the ID from the form value to an integer id, err := strconv.Atoi(r.FormValue("id")) if err != nil { // Send a bad request response if the ID is not valid http.Error(w, "Invalid ID", http.StatusBadRequest) return } // Delete the note with the given ID DeleteNote(id) // Redirect the user back to the homepage after deleting the note http.Redirect(w, r, "/", http.StatusSeeOther) }