title: How to use JSON key instead of P12 in Google Spreadsheet Authentication with PHP?
body: <p>I am working with Google Spreadsheet in PHP. When I use P12 key it works perfect, but when I use JSON key instead of P12 key while Authenticating with Google Spread Sheet, it is giving </p>
  
  <blockquote>
    <p>Fatal error: Uncaught exception 'Google_Auth_Exception' with message 'Unable to load private key'</p>
  </blockquote>
  
  <p>Please tell me how to use JSON key while Authenticating with Google Spread Sheet in PHP.</p>