GoLang Tutorial - Web App 2 (Using net/http)

Continued from Web Application Part 1.

In this post, we'll be using the net/http to serve the wiki pages we created in the previous tutorial.

Users need to view our wiki page. To do that we may want to create a handler, viewHandler which will handle URLs prefixed with /view/.

func viewHandler(w http.ResponseWriter, r *http.Request) {
    title := r.URL.Path[len("/view/"):]
    p, _ := loadPage(title)
    fmt.Fprintf(w, "<h1>%s</h1><div>%s</div>", p.Title, p.Body)
}

Not that we used "_" to ignore the error return value from loadPage. This is done here for simplicity and generally considered bad practice. We will take care of this later.

First, this function extracts the page title from r.URL.Path, the path component of the request URL. The Path is re-sliced with [len("/view/"):] to drop the leading "/view/" component of the request path. This is because the path will invariably begin with "/view/", which is not part of the page's title.

The function then loads the page data, formats the page with a string of simple HTML, and writes it to w, the http.ResponseWriter.

To use this handler, we rewrite our main function to initialize http using the viewHandler to handle any requests under the path /view/:

func main() {
    http.HandleFunc("/view/", viewHandler)
    log.Fatal(http.ListenAndServe(":8080", nil))
}

We need a page data (as test.txt) like this:

Hello GoLang

Then, compile our code, and try serving a wiki page:

With this web server running, a visit to http://localhost:8080/view/test should show a page titled "test" containing the words "Hello GoLang":

Continues to Web Application Part 3 (Adding "edit" capability).

Go Tutorial

1. GoLang Tutorial - HelloWorld
2. Calling code in an external package & go.mod / go.sum files
3. Workspaces
4. Workspaces II
5. Visual Studio Code
6. Data Types and Variables
7. byte and rune
8. Packages
9. Functions
10. Arrays and Slices
11. A function taking and returning a slice
12. Conditionals
13. Loops
14. Maps
15. Range
16. Pointers
17. Closures and Anonymous Functions
18. Structs and receiver methods
19. Value or Pointer Receivers
20. Interfaces
21. Web Application Part 0 (Introduction)
22. Web Application Part 1 (Basic)
23. Web Application Part 2 (Using net/http)
24. Web Application Part 3 (Adding "edit" capability)
25. Web Application Part 4 (Handling non-existent pages and saving pages)
26. Web Application Part 5 (Error handling and template caching)
27. Web Application Part 6 (Validating the title with a regular expression)
28. Web Application Part 7 (Function Literals and Closures)
29. Building Docker image and deploying Go application to a Kubernetes cluster (minikube)
30. Serverless Framework (Serverless Application Model-SAM)
31. Serverless Web API with AWS Lambda
32. Arrays vs Slices with an array left rotation sample
33. Variadic Functions
34. Goroutines
35. Channels ("<-")
36. Channels ("<-") with Select
37. Channels ("<-") with worker pools
38. Defer
39. GoLang Panic and Recover
40. String Formatting
41. JSON
42. SQLite
43. Modules 0: Using External Go Modules from GitHub
44. Modules 1 (Creating a new module)
45. Modules 2 (Adding Dependencies)
46. AWS SDK for Go (S3 listing)
47. Linked List
48. Binary Search Tree (BST) Part 1 (Tree/Node structs with insert and print functions)
49. Go Application Authentication I (BasicAuth, Bearer-Token-Based Authentication)
50. Go Application Authentication II (JWT Authentication)