Fairing

What’s fairing? It’s an abstraction to avoid over-using the middleware.

But we still need some hooks to record some data or modifying the input/output for certain purpose, to keep this ability, we made fairing, this is how it looks like:

package example

type Logger struct {
    rocket.Fairing
}

func (l *Logger) OnRequest(r *http.Request) *http.Request {
    log.Printf("request: %#v\n", r)
    return r
}
func (l *Logger) OnResponse(r *response.Response) *response.Response {
    log.Printf("response: %#v\n", r)
    return r
}
// in main function or entrypoint
rocket.Ignite(8080).
    Attach(&Logger{}).
    // Mount...
    Launch()

We can see some points, first, we can implement two kinds of fairing callbacks

• func OnRequest(r *http.Request) *http.Request

  this would be called before handlers get request

• func OnResponse(r *response.Response) *response.Response

  this would be called after handlers done handling

• func OnLaunch(r *rocket.Rocket)

  this would be called at launch time and get meta data of rocket

  For example:

  package example
  
  func (c *Configurator) OnLaunch(r *rocket.Rocket) {
      r.MultiFormBodySizeLimit = 20 // 20 MB
  }
  

then we can use the fairing implementor by using Attach method to emit it. We can call Attach several times, but carefully with it since it could modify request and response!

Why embedded rocket.Fairing? It would provide default behavior for OnRequest and OnResponse if you didn’t provide one, so it’s a good practice to embedded since we could add more fairing methods into it.