Google calendar in Ionic

Question

I'm trying to create a mobile app using Ionic and for this app we would need to make use of the Google calendar. The objective is to create an app where certain people can subscribe themselves to some events. These events are now created in the Google calendar and we would like to be able to subscribe ourselves either in our Google calendar our in the app which will only show certain events.

I've been looking for ages now but I just cant figure out how to connect with Google calendar in Ionic.

Please help me getting started.

Answer 1

I have been able to solve it myself but not directly in Ionic.

I contacted my node.js backend and in node.js is is possible to contact the google api...

let eventCategories = require('./event.model');

let fs = require('fs');
let readline = require('readline');
let google = require('googleapis');
let googleAuth = require('google-auth-library');

// If modifying these scopes, delete your previously saved credentials
// at ~/.credentials/calendar-nodejs-quickstart.json
let SCOPES = ['https://www.googleapis.com/auth/calendar.readonly'];
let TOKEN_DIR = (process.env.HOME || process.env.HOMEPATH ||
    process.env.USERPROFILE) + '/.credentials/';
let TOKEN_PATH = TOKEN_DIR + 'calendar-nodejs-quickstart.json';


module.exports = {
  getEventCategories,  
  getEvents
};

function getEventCategories(){
  return eventCategories.find({});
}

function getEvents(calendarId) {
  return loadClientSecrets()
    .then(res => authorize(JSON.parse(res))
                    .then(response => listEvents(response, calendarId)))

}

function loadClientSecrets(){
  return new Promise(function (fulfill, reject){
    fs.readFile('client_secret.json', function processClientSecrets(err, content){
      if (err){
        console.log('Error loading client secret file: '+ err);
        reject(err);
      }
      else fulfill(content);
    }) 
  })
}



/**
 * Create an OAuth2 client with the given credentials, and then execute the
 * given callback function.
 */
function authorize(credentials) {
  return new Promise(function (fulfill, reject){
    let clientSecret = credentials.installed.client_secret;
    let clientId = credentials.installed.client_id;
    let redirectUrl = credentials.installed.redirect_uris[0];
    let auth = new googleAuth();
    let oauth2Client = new auth.OAuth2(clientId, clientSecret, redirectUrl);

    // Check if we have previously stored a token.
    fs.readFile(TOKEN_PATH, function(err, token) {
      if (err) {
        fulfill(getNewToken(oauth2Client));
      } else {
        oauth2Client.credentials = JSON.parse(token);
        fulfill(oauth2Client);
      }
    });
  })
}

/**
 * Get and store new token after prompting for user authorization, and then
 * execute the given callback with the authorized OAuth2 client.
 */
function getNewToken(oauth2Client) {
  new Promise (function (fulfill, reject){
    let authUrl = oauth2Client.generateAuthUrl({
      access_type: 'offline',
      scope: SCOPES
    });
    console.log('Authorize this app by visiting this url: ', authUrl);
    let rl = readline.createInterface({
      input: process.stdin,
      output: process.stdout
    });
    rl.question('Enter the code from that page here: ', function(code) {
      rl.close();
      oauth2Client.getToken(code, function(err, token) {
        if (err) {
          console.log('Error while trying to retrieve access token', err);
          reject(err);
        }
        oauth2Client.credentials = token;
        storeToken(token);
        fulfill(oauth2Client);
      });
    });
  })
}

/**
 * Store token to disk be used in later program executions.
 */
function storeToken(token) {
  try {
    fs.mkdirSync(TOKEN_DIR);
  } catch (err) {
    if (err.code != 'EEXIST') {
      throw err;
    }
  }
  fs.writeFile(TOKEN_PATH, JSON.stringify(token));
  console.log('Token stored to ' + TOKEN_PATH);
}

/**
 * Lists the next 10 events on the user's primary calendar.
 */
function listEvents(auth, calendarId) {
  return new Promise(function ( fulfill, reject){
    var calendar = google.calendar('v3');
    calendar.events.list({
      auth: auth,
      calendarId: calendarId,
      timeMin: (new Date()).toISOString(),
      maxResults: 10,
      singleEvents: true,
      orderBy: 'startTime'
    }, function(err, response) {
      if (err) {
        console.log('The API returned an error: ' + err);
        reject(err);
      }
      let events = response.items;
      if (events.length == 0) {
        console.log('No upcoming events found.');
      } else {
        console.log('Upcoming 10 events:');
        for (let i = 0; i < events.length; i++) {
          let event = events[i];
          let start = event.start.dateTime || event.start.date;
          console.log('%s - %s', start, event.summary);
        }
        fulfill(events)
      }
    });
  })
}