How to handle MIME-based content negotiation for RESTful APIs in Go?

To handle MIME-based content negotiation for RESTful APIs in Go, you can follow these steps:

Install the necessary libraries: You will need to install the net/http and github.com/gorilla/mux packages. You can install them using the following command:
go get -u github.com/gorilla/mux
Import the required packages: In your Go source file, import the necessary packages:
import ( "net/http" "github.com/gorilla/mux" )
Define the content types that your API supports: You need to define the supported content types by creating a constant slice of strings. For example:
const ( ContentTypeJSON = "application/json" ContentTypeXML = "application/xml" ) var SupportedContentTypes = []string{ ContentTypeJSON, ContentTypeXML, }
Implement the content negotiation logic: In your API handler function, you can use the negotiator function to handle the content negotiation with the client. This function takes the request and returns the appropriate content type to be used for the response. For example:

func handler(w http.ResponseWriter, r *http.Request) {
    // Call the negotiator function to get the appropriate content type
    contentType := negotiator(r)

    // Set the Content-Type header in the response
    w.Header().Set("Content-Type", contentType)

    // Add your logic to generate the response here
    // ...
}

func negotiator(r *http.Request) string {
    // Check if the request has the "Accept" header
    accept := r.Header.Get("Accept")

    // If the Accept header is not set, return the first supported content type
    if accept == "" {
        return SupportedContentTypes[0]
    }

    // Iterate over the supported content types and check if any matches the Accept header
    for _, contentType := range SupportedContentTypes {
        if strings.Contains(accept, contentType) {
            return contentType
        }
    }

    // If no match is found, return an error or respond with a default content type
    return SupportedContentTypes[0]
}

Define your API routes and attach the handler function: Use the mux package to define your API routes and attach the handler function to the corresponding route. For example:

func main() {
    r := mux.NewRouter()
    r.HandleFunc("/api/resource", handler).Methods("GET")
    http.ListenAndServe(":8000", r)
}

With the above steps, your RESTful API in Go can handle MIME-based content negotiation. The negotiator function checks the "Accept" header of the client's request and returns the appropriate content type to be used in the response.