A helper function to read the content from an `http.Response` body and refill the body with another `io.ReadCloser`, so that it can be read again.

ReadResponseBody.go

import (
	"bytes"
	"io/ioutil"
	"net/http"
)

// Function readResponseBody is a helper function to read the content from a response's body,
// and refill the body with another io.ReadCloser, so that it can be read again.
func readResponseBody(resp *http.Response) (content []byte, err error) {
	// Get the content
	content, err = ioutil.ReadAll(resp.Body)

	// Reset the response body
	rCloser := ioutil.NopCloser(bytes.NewBuffer(content))
	resp.Body = rCloser

	return
}

If you don't refill after reading, the body will return null.