# Handling Forms - Google App Engine - Google Code

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# Handling Forms

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.

## Handling Web Forms

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.

## Next...

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.