mux.Vars not working

I'm running on HTTPS (port 10443) and use subroutes:

mainRoute := mux.NewRouter()
mainRoute.StrictSlash(true)
mainRoute.Handle("/", http.RedirectHandler("/static/", 302))
mainRoute.PathPrefix("/static/").Handler(http.StripPrefix("/static", *fh))

// Bind API Routes
apiRoute := mainRoute.PathPrefix("/api").Subrouter()

apiProductRoute := apiRoute.PathPrefix("/products").Subrouter()
apiProductRoute.Handle("/", handler(listProducts)).Methods("GET")

And the functions:

func listProducts(w http.ResponseWriter, r *http.Request) (interface{}, *handleHTTPError) {
	vars := mux.Vars(r)

	productType, ok := vars["id"]
	log.Println(productType)
	log.Println(ok)
}

ok is false and I have no idea why. I'm doing a simple ?type=model after my URL..

When you enter a URL like somedomain.com/products?type=model you're specifying a query string, not a variable.

Query strings in Go are accessed via r.URL.Query - e.g.

vals := r.URL.Query() // Returns a url.Values, which is a map[string][]string
productTypes, ok := vals["type"] // Note type, not ID. ID wasn't specified anywhere.
var pt string
if ok {
    if len(productTypes) >= 1 {
        pt = productTypes[0] // The first `?type=model`
    }
}

As you can see, this can be a little clunky as it has to account for the map value being empty and for the possibility of a URL like somedomain.com/products?type=model&this=that&here=there&type=cat where a key can be specified more than once.

As per the gorilla/mux docs you can use route variables:

   // List all products, or the latest
   apiProductRoute.Handle("/", handler(listProducts)).Methods("GET")
   // List a specific product
   apiProductRoute.Handle("/{id}/", handler(showProduct)).Methods("GET")

This is where you would use mux.Vars:

vars := mux.Vars(request)
id := vars["id"]

Hope that helps clarify. I'd recommend the variables approach unless you specifically need to use query strings.

An easier way to solve this is to add query parameters in your route through Queries, like:

apiProductRoute.Handle("/", handler(listProducts)).
                Queries("type","{type}").Methods("GET")

You can get it using:

v := mux.Vars(r)
type := v["type"]

NOTE: This might not have been possible when the question was originally posted but I stumbled across this when I encountered a similar problem and the gorilla docs helped.