This is a libary that handles content negotiation in web applications written in Go.

To return JSON/XML out of the box simple put this in your route handler:

func getUser(w http.ResponseWriter, req *http.Request) {
    user := &User{"Joe","Bloggs"}
    if err := negotiator.Negotiate(w, req, user); err != nil {
      http.Error(w, err.Error(), http.StatusInternalServerError)
    }
}

To add your own negotiator, for example you want to write a PDF with your model, do the following:

1. Create a type that conforms to the ResponseProcessor interface

2. Call negotiator.New(responseProcessors ...ResponseProcessor) and pass in a your custom processor. When your request handler calls negotiator.Negotiate(w,req,model,errorHandler) it will render a PDF if your Accept header defined it wanted a PDF response.