Go, AppEngine: How to structure templates for application

go google-app-engine

One of my favorite features of Go is the ability to easily add handlers inside of packages. This greatly simplifies the processes of writing modular code.

For Example:

File Structure

|-- app.yaml
|-- app
|   +-- http.go
|-- templates
|   +-- base.html
+-- github.com
    +-- storeski
        +-- appengine
            |-- products
            |   |-- http.go
            |   +-- templates
            |       |-- list.html
            |       +-- detail.html 
            +-- account
                |-- http.go
                +-- templates
                    |-- overview.html
                    +-- notifications.html

Each packages has a http.go file that takes ownership of a url prefix. For example the products package under github.com/storeski/appengine/products would own any inbound url starting with /products.

With this modular approach it is beneficial to store the templates within the products package. If you would like to maintain a consistant base template for the site you can establish a convention where you extend templates/base.html.

Example

templates/base.html

<!DOCTYPE HTML>
<html>
  <head>
    <title>{{.Store.Title}}</title>
  </head>

  <body>
    <div id="content">
      {{template "content" .}}
    </div>
  </body>
</html>

github.com/storeski/appengine/products/templates/list.html

{{define "content"}}
  <h1> Products List </h1>
{{end}}

github.com/storeski/appengine/products/http.go

func init() {
  http.HandleFunc("/products", listHandler)
}

var listTmpl = template.Must(template.ParseFiles("templates/base.html",
  "github.com/storeski/appengine/products/templates/list.html"))

func listHandler(w http.ResponseWriter, r *http.Request) {

  tc := make(map[string]interface{})
  tc["Store"] = Store
  tc["Products"] = Products

  if err := listTmpl.Execute(w, tc); err != nil {
    http.Error(w, err.Error(), http.StatusInternalServerError)
  }
}

This approach is very exciting because it makes the sharing of apps/package trivial. If I write a package that handles authentication which takes ownership of the /auth url. Any developer that, then, adds the package to their product root instantly has all of the functionality. All they have to do is create a base template (templates/base.html) and direct their users to /auth.

Go, AppEngine: How to structure templates for application

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