Path

Manage named paths (aka routes) used within your web application. This is NOT a router!

Overview

The goal of the path package is to make it easier to manage named paths in a Go web application without having to rely on hard-coded paths. Here is a basic example:

var pb path.Builder
pb.Set("edit_widget", "/widgets/:id/edit")

// ... in an http handler
http.Redirect(w, r, pb.Path("edit_widget", path.Params{
  "id": 123,
}), http.StatusFound) // redirects to "/widgets/123/edit"

You can also leverage the path package in your templates using the FuncMap method:

var pb path.Builder
pb.Set("edit_widget", "/widgets/:id/edit")
tpl := template.New("").Funcs(pb.FuncMap()).Parse(`
  {{edit_widget_path (params "id" .Widget.ID)}}`)
data := struct {
  Widget Widget
}{
  Widget: Widget{
    ID: 123,
  },
}
tpl.Execute(w, data)
// Writes the following output:
//   /widgets/123/edit

Installation

To install this package, simply go get it:

go get github.com/joncalhoun/form

Use cases

This is much easier to understand with an example, so let's just jump right into one.

Imagine that I had a handler to process the creation of widgets. Once a widget is created I might want to redirect the user to a page where they can edit the widget's details. That redirect might look something like this before using the path package:

func CreateWidget(w http.ResponseWriter, r *http.Request) {
  var widget Widget
  // ... create the widget

  path := fmt.Sprintf("/widgets/%v/edit", widget.ID)
  http.Redirect(w, r, path, http.StatusFound)
}

This works well enough, but relies on paths being hard coded into your application or defined as constants somewhere, and I often found myself writing the exact same code in every web application to turn paths in the format

You could try to fix this with constants, or by using the named routes in something like gorilla/mux, but I found that in nearly all web applications I tend to write the exact same path handling logic and typically didn't want to be too reliant on a specific router. The path package is intended to provide me with a single solution that can be easily used regardless of what router or whatever else I am using.

Using path with other routers

It is also possible to use this along with another router, like gorilla/mux, simply by replacing params with the format your router expects:

var pb path.Builder
pb.Set("edit_widget", "/widgets/:id/edit")

r := mux.NewRouter()
r.HandleFunc(pb.Path("edit_widget", path.Params{
  "id": "{id:[0-9]+}",
}), EditWidgetHandler) // this generates the path /widgets/{id:[0-9]+}/edit

This works because the path.Builder simply replaces the ID with the value {id:0-9]+} which is a regex specifying the ID for gorilla/mux.

Unset params are returned unchanged

If you define a URL param and don't provide a value for it the path.Builder will simply return the param as-is.

var pb path.Builder
pb.Set("edit_widget", "/widgets/:id/edit")

pb.Path("edit_widget", nil) // returns /widgets/:id/edit