HTML Templates · Building Web Apps with Go

# HTML Templates Serving HTML is an important job for some web applications. Go has one of myfavorite templating languages to date. Not for its features, but for itssimplicity and out of the box security. Rendering HTML templates is almost aseasy as rendering JSON using the 'html/template' package from the standardlibrary. Here is what the source code for rendering HTML templates looks like: ~~~ package main import ( "html/template" "net/http" "path" ) type Book struct { Title string Author string } func main() { http.HandleFunc("/", ShowBooks) http.ListenAndServe(":8080", nil) } func ShowBooks(w http.ResponseWriter, r *http.Request) { book := Book{"Building Web Apps with Go", "Jeremy Saenz"} fp := path.Join("templates", "index.html") tmpl, err := template.ParseFiles(fp) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } if err := tmpl.Execute(w, book); err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) } } ~~~ This is the following template we will be using. It should be placed in a`templates/index.html` file in the directory your program is run from: ~~~ <html> <h1>{{ .Title }}</h1> <h3>by {{ .Author }}</h3> </html> ~~~ ## Exercises 1. Look through the docs for `text/template` and `html/template` package. Play with the templating language a bit to get a feel for its goals, strengths, and weaknesses. 1. In the example we parse the files on every request, which can be a lot of performance overhead. Experiment with parsing the files at the beginning of your program and executing them in your `http.Handler` (hint: make use of the `Copy()` method on `html.Template`). 1. Experiment with parsing and using multiple templates.