Google Calendar API: How can I get the events of a public calendar without user log in?

Question

I'm trying to use the Google Calendar API to get a list of the most recent events of a public calendar that I own. It's so my client can edit a calendar and the info will appear on the website. Here is my code so far (which I edited from an example from Google):

<html>
  <head>
    <script type="text/javascript">
      // Your Client ID can be retrieved from your project in the Google
      // Developer Console, https://console.developers.google.com
      var CLIENT_ID = '<MY-CLIENT-ID>';

      var SCOPES = ["https://www.googleapis.com/auth/calendar.readonly"];

      /**
       * Check if current user has authorized this application.
       */
      function checkAuth() {
        gapi.auth.authorize(
          {
            'client_id': CLIENT_ID,
            'scope': SCOPES.join(' '),
            'immediate': true
          }, handleAuthResult);
      }

      /**
       * Handle response from authorization server.
       *
       * @param {Object} authResult Authorization result.
       */
      function handleAuthResult(authResult) {
        var authorizeDiv = document.getElementById('authorize-div');
        if (authResult && !authResult.error) {
          // Hide auth UI, then load client library.
          authorizeDiv.style.display = 'none';
          loadCalendarApi();
        } else {
          // Show auth UI, allowing the user to initiate authorization by
          // clicking authorize button.
          authorizeDiv.style.display = 'inline';
        }
      }

      /**
       * Load Google Calendar client library. List upcoming events
       * once client library is loaded.
       */
      function loadCalendarApi() {
        gapi.client.load('calendar', 'v3', listUpcomingEvents);
      }

      /**
       * Print the summary and start datetime/date of the next ten events in
       * the authorized user's calendar. If no events are found an
       * appropriate message is printed.
       */
      function listUpcomingEvents() {
        var request = gapi.client.calendar.events.list({
          'calendarId': '<MY-PUB-CAL-ID>',
          'timeMin': (new Date()).toISOString(),
          'showDeleted': false,
          'singleEvents': true,
          'maxResults': 10,
          'orderBy': 'startTime'
        });

        request.execute(function(resp) {
          var events = resp.items;
          appendPre('Upcoming events:');

          if (events.length > 0) {
            for (i = 0; i < events.length; i++) {
              var event = events[i];
              var when = event.start.dateTime;
              if (!when) {
                when = event.start.date;
              }
              appendPre(event.summary + ' (' + when + ')')
            }
          } else {
            appendPre('No upcoming events found.');
          }

        });
      }

      /**
       * Append a pre element to the body containing the given message
       * as its text node.
       *
       * @param {string} message Text to be placed in pre element.
       */
      function appendPre(message) {
        var pre = document.getElementById('output');
        var textContent = document.createTextNode(message + '\n');
        pre.appendChild(textContent);
      }

    </script>
    <script src="https://apis.google.com/js/client.js?onload=loadCalendarApi">
    </script>
  </head>
  <body>
    <div id="authorize-div" style="display: none">
      <span>Authorize access to Google Calendar API</span>
      <!--Button for the user to click to initiate auth sequence -->
      <button id="authorize-button" onclick="handleAuthClick(event)">
        Authorize
      </button>
    </div>
    <pre id="output"></pre>
  </body>
</html>

So this is almost working, but when I make this request I get this error:

{
 "error": {
  "errors": [
   {
    "domain": "global",
    "reason": "required",
    "message": "Login Required",
    "locationType": "header",
    "location": "Authorization"
   }
  ],
  "code": 401,
  "message": "Login Required"
 }
}

Why am I not authenticated to access this public calendar as read only??

score 3 · Accepted Answer · edited May 23 '17 at 12:19

Your error means that the credentials on the request aren't correct (or are missing). Use the library's http logging feature to examine the requests and responses to the Google API server. Each request should have an "Authorization" header with a bearer token. From this thread, you need to pass Authorization: Oauth {access token} in your headers.

You can check on this SO post: How to list Google Calendar Events without User Authentication

What you need to do is use a Service account for this. You will then be able add the service accounts email address as a user to the calendar for your website. The Service account will then be able to access this calendar including the events.

You can also register in a developer console and create an API key. Then you can do:

GET https://www.googleapis.com/calendar/v3/calendars/<CALENDAR_EMAIL>/events?key={YOUR_API_KEY}

Hope this helps!

Sorry, I'm a bit confused. So I went and created a Service Account that should be linked to this project, and added that account to the calendar so it's able to view it. But I'm not sure where to go from there. The SA has a Key ID, but I'm not sure if I'm supposed to use that anywhere. My code is the exact same as when I posted earlier, I'm not sure what I'm supposed to modify:( — Diericx, Sep 28 '16 at 18:30

Google Calendar API: How can I get the events of a public calendar without user log in?

1 Answers1