If we want users to be able to post their own greetings, we need a way to
process information submitted by the user with a web form. The Go
http package makes processing form data easy.
Replace the contents of myapp/hello/hello.go with the
following:
package hello
import (
"fmt"
"http"
"template"
)
func init() {
http.HandleFunc("/", root)
http.HandleFunc("/sign", sign)
}
func root(w http.ResponseWriter, r *http.Request) {
fmt.Fprint(w, guestbookForm)
}
const guestbookForm = `
<html>
<body>
<form action="/sign" method="post">
<div><textarea name="content" rows="3" cols="60"></textarea></div>
<div><input type="submit" value="Sign Guestbook"></div>
</form>
</body>
</html>
`
func sign(w http.ResponseWriter, r *http.Request) {
err := signTemplate.Execute(w, r.FormValue("content"))
if err != nil {
http.Error(w, err.String(), http.StatusInternalServerError)
}
}
var signTemplate = template.Must(template.New("sign").Parse(signTemplateHTML))
const signTemplateHTML = `
<html>
<body>
<p>You wrote:</p>
<pre>{{html .}}</pre>
</body>
</html>
`
Reload the page to see the form, then try submitting a message.
This version has two handlers: the path / is mapped to
root, which displays a web form. The path /sign is
mapped to sign, which displays the data submitted by the web form.
The sign function gets the form data by calling
r.FormValue and passes it to signTemplate.Execute
that writes the rendered template to the http.ResponseWriter.
In the template code, the content is filtered with the html
filter to escape HTML special characters.
Now that we can collect information from the user, we need a place to put it and a way to get it back.
Continue to Using the Datastore.