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Producing Web Responses

Responses

http.ResponseWriter

  • The type http.ResponseWriter is an interface type that represents the response being sent back to the client
  • It defines only three methods
    • Header(): returns the header map and allows you to set the response header
    • WriteHeader(int): sets the response status code
    • Write([]byte) (int, error): writes the response body
  • Header() and WriteHeader() have to be called before writing the body
  • The method Write() ensures that the response also implements the io.Writer interface
  • So all functions and methods working with io.Writer can also be used writing to the http.ResponseWriter

Examples

Hello, World!

func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Content-Type", "text/plain")
    w.WriteHeader(http.StatusOK)
    w.Write([]byte("Hello, World!"))
}

Accept

func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    accept := r.Header.Get("Accept")

    w.Header().Set("Content-Type", "text/plain")
    w.WriteHeader(http.StatusOK)
    fmt.Fprintf(w, "Your Accept header is: %s", accept)
}