Golang : Fixing Gorilla mux http.FileServer() 404 problem

I'm in the process of developing a web application to handle my landlord to tenants relationships in a better way and previously I used net/http's mux to handle the multiplexer routing without any issue. Everything was fine and dandy until I cleared by browser's cache. Only then I noticed that my web application interface became broken with all the css, js and fonts files missing. Every attempts to navigate to those files returned error 404 instead. So what's going on?

After some investigation, I found out that the problem arises after changing the multiplexer from net/http to github.com/gorilla/mux

The trouble is caused by the way Gorilla's mux matching an URL address compared to net/http. You will have to dig into the documentations at https://godoc.org/github.com/gorilla/mux and https://golang.org/pkg/net/http/#ServeMux to see how they worked.

Anyway, to solve this http.FileServer() error 404 problem, all I need to do is to change the following code

From

 mx.Handle("/css", http.FileServer(webFrontEnd.HTTPBox()))

To

 mx.PathPrefix("/css").Handler(http.FileServer(webFrontEnd.HTTPBox()))

Why add PathPrefix() function?

According to the documentation about PathPrefix() function:

Note that the path provided to PathPrefix() represents a "wildcard": calling PathPrefix("/static/").Handler(...) means that the handler will be passed any request that matches "/static/*". This makes it easy to serve static files with mux:

Hope this helps and happy coding!

References :

https://golang.org/pkg/net/http/#ServeMux

https://godoc.org/github.com/gorilla/mux