**Course Title:** Mastering Go: From Basics to Advanced Development **Section Title:** Building Web Applications with Go **Topic:** Develop a simple web application using Go and the net/http package.(Lab topic) **Overview:** In this lab topic, you will learn how to develop a simple web application using Go and the net/http package. You will build a basic web server and create a simple RESTful API. This hands-on experience will help you solidify your understanding of web development with Go. **Step 1: Preparing Your Environment** Before you start, make sure you have the Go programming language installed on your computer and your favorite IDE set up. You should also have a basic understanding of the net/http package, as covered in previous topics. **Step 2: Creating a Basic Web Server** Create a new file called `main.go` and add the following code: ```go package main import ( "fmt" "net/http" ) func helloHandler(w http.ResponseWriter, r *http.Request) { fmt.Fprint(w, "Hello, World!") } func main() { http.HandleFunc("/", helloHandler) http.ListenAndServe(":8080", nil) } ``` This code creates a new HTTP server that listens on port 8080 and handles requests to the root URL (`"/"`) with a simple "Hello, World!" message. **Step 3: Running the Web Server** To run the web server, execute the following command in your terminal: ``` go run main.go ``` Open your favorite web browser and navigate to `http://localhost:8080`. You should see the "Hello, World!" message. **Step 4: Creating a Simple RESTful API** To create a simple RESTful API, you will add two new handler functions: `getBooksHandler` and `addBookHandler`. These functions will handle GET and POST requests, respectively. Add the following code to the `main.go` file: ```go func getBooksHandler(w http.ResponseWriter, r *http.Request) { books := []string{"Book 1", "Book 2", "Book 3"} json.NewEncoder(w).Encode(books) } func addBookHandler(w http.ResponseWriter, r *http.Request) { var book string json.NewDecoder(r.Body).Decode(&book) // Simulate a database operation fmt.Println("Added book:", book) http.Redirect(w, r, "/", http.StatusSeeOther) } ``` These functions handle GET requests by returning a list of books in JSON format, and POST requests by simulating a database operation and redirecting the client to the root URL. **Step 5: Registering the Handlers** To register the new handlers, add the following code to the `main.go` file: ```go func main() { http.HandleFunc("/", helloHandler) http.HandleFunc("/books", getBooksHandler) http.HandleFunc("/add-book", addBookHandler) http.ListenAndServe(":8080", nil) } ``` **Step 6: Testing the API** To test the API, use a tool like `curl` from the command line. Execute the following commands: ```bash curl http://localhost:8080/books curl -X POST -H "Content-Type: application/json" -d '{"book": "New Book"}' http://localhost:8080/add-book ``` You should see the list of books and the response from the `addBookHandler` function. **Conclusion:** In this lab topic, you built a simple web application using Go and the net/http package. You created a basic web server, a simple RESTful API, and tested it using `curl`. This hands-on experience should help you solidify your understanding of web development with Go. **What's Next?** In the next topic, 'Introduction to databases and SQL,' you will learn about the basics of databases and SQL. This topic will provide a foundation for working with databases in your Go applications. **Additional Resources:** * Go's net/http package documentation: <https://golang.org/pkg/net/http/> * Go by Example: RESTful API: <https://gobyexample.com/restful-api> * How to Use Go's net/http Package for Web Development: <https://www.golang-book.com/books/intro/12> **Leave a Comment/Ask for Help:** If you have any questions or need help with any of the concepts presented in this topic, please leave a comment below.