Implementing ICS/ICAL to sync calendars with the event schedule in Open Event Webapp

As an end result, we want to provide a button to the user which will export the whole data of the event schedule to an ICS file and present it to the user for download after clicking the button. The whole work regarding the feature can be seen here.

Instead of implementing the whole specification ourselves which would be much tougher and time-consuming, we looked for some good open source libraries to do a bit of heavy lifting for us. After searching exhaustively for the solution, we came across this library which seemed appropriate for the job. The heart of the library is a function which takes in an object which contains information about the session. It expects information about the start and end time, subject, description and location of the session. Here is an excerpt from the function. The whole file can be seen here

var addEvent = function (session) {
 var calendarEvent = [
   'BEGIN:VEVENT',
   'UID:' + session.uid,
   'CLASS:PUBLIC',
   'DESCRIPTION:' + session.description,
   'DTSTART;VALUE=DATETIME:' + session.begin,
   'DTEND;VALUE=DATE:' + session.stop,
   'LOCATION:' + session.location,
   'SUMMARY;LANGUAGE=en-us:' + session.subject,
   'TRANSP:TRANSPARENT',
   'END:VEVENT'
 ];
 calendarEvents.push(calendarEvent);
};

We need to call the above function for every session in the event schedule. In the schedule template file, we have the jsonData object available which contain all the information about the event. It contains a field called timeList which contains the chronological order of the different sessions taking place throughout the events. The structure of that sub-object is something like this.

[{'slug': '2017-03-20', 'times': {'caption' : '09:00-09:30', 'sessions': [{'title': 'Welcome', 'description': 'Opening of the event', 'start': '09:00', 'end': '09:30'}]}]

So, we define a function for iterating through every session in the above object and adding it to the calendar. We can use most of the attributes directly but have to modify the date and time fields of the session to an appropriate format before adding it. The specification expects time in the ISO 8601 Format. You can read more about the specification here. For eg – If the date is 2017-03-20 and the time is 09:30 then it should be written as 20170320T093000. Here is some part of the function here

function exportICS() {
 var scheduleArr = {{{json timeList}}};
 // Helper functions for converting time to ISO 8601 Format
 function removeDashFromDate(date) {
   return date.replace(/-/g, '');
 }
 function removeColonFromTime(time) {
   return time.replace(/:/g, '');
 }
 // Iteration through the object and adding every session to the calendar
 scheduleArr.forEach(function(scheduleDay) {
   var date = removeDashFromDate(scheduleDay.slug);
   scheduleDay.times.forEach(function(time) {
     time.sessions.forEach(function(session) {
       var sessObj = {};
       sessObj.begin = date + 'T' + removeColonFromTime(session.start) + '00';
       sessObj.stop = date + 'T' + removeColonFromTime(session.end) + '00';
       sessObj.subject = session.title;
       sessObj.description = session.description;
       sessObj.location = session.location;
       cal.addEvent(sessObj);
     });
   });
 });
 cal.download('calendar', 'ics', false); // Download the ics file of the calendar
}

After defining the function, we add a button for starting the download of the whole schedule of the event. On clicking, we call the function which initiates the download after all the sessions of the event have been added.

<span class="schedule-download">
 <button type="button" class="btn btn-default export-schedule"><i class="fa fa-calendar" aria-hidden="true"></i></button>
</span>

$('.export-schedule').click(function() {
 exportICS();
});

Here is the export schedule button

65203af9-3962-4ab5-9655-3250bf2253a0.png

This is the download pop-up of the ICS file of the event.

Screenshot from 2017-08-10 21-56-16.png

After importing it in the Google calendar

Screenshot from 2017-08-10 23-01-22.png

References

Implementing Logging Functionality in Open Event Webapp

  • INFO: Info statements give information about the task currently being performed by the webapp
  • SUCCESS: Success statements give the information of a task being successfully completed
  • ERROR: Error statements give information about a task failing to complete. These statements also contain a detailed error log

Along with the type of the statement, the object also contains information about the task. For all types of statements, there is a field called smallMessage containing short information about the task. For the ERROR statements where more information is required to see what went wrong, the message object has an additional field called largeMessage which holds detailed information about the event.

We also create a new file called buildlogger.js and define a function for creating log statements about the tasks being performed by generator and export it. The function creates a message object from the arguments received and then return it to the client under the buildLog event via the socket IO.

exports.addLog = function(type, smallMessage, socket, largeMessage) {
 var obj = {'type' : type, 'smallMessage' : smallMessage, 'largeMessage': largeMessage};
 var emit = false;
 if (socket.constructor.name === 'Socket') {
   emit = true;
 }
 if (emit) {
   socket.emit('buildLog', obj);
 }
};

Most of the steps of the generation process are defined in the generator.js file. So, we include the logging file there and call the addLog function for sending logs messages to the client. All the different steps like cleaning temporary folders, copying assets, fetching JSONs, creating the website directory, resizing images etc have multiple log statements for their inception and successful/erroneous completion. Below is an excerpt from the cleaning step.

var logger = require('./buildlogger.js');
 async.series([
   (done) => {
     console.log('CLEANING TEMPORARY FOLDERS\n');
     logger.addLog('Info', 'Cleaning up the previously existing temporary folders', socket);
     fs.remove(distHelper.distPath + '/' + appFolder, (err) => {
       if(err !== null) {
         // Sending Error Message when the remove process failed
         logger.addLog('Error', 'Failed to clean up the previously existing temporary folders', socket, err);
       }
       // Success message denoting the completion of the step
       logger.addLog('Success', 'Successfully cleaned up the temporary folders', socket);
       done(null, 'clean');
     });
   }
 )]

But we have only done the server side work now. We also have to handle the message on the client side. We send the message object to the client under the event buildLog and set up a listener for that event to catch the sent message. After the message object is received on the client side, we extract the information out of that object and then display it on the website. We have a div having an id of buildLog for displaying the log information. The content of the message is dynamically added to it as soon as it is received from the server. All the client side logic is handled in the form.js file.

socket.on('buildLog', function(data) {
   var spanElem = $('<span></span>'); // will contain the info about type of statement
   var spanMess = $('<span></span>'); // will contain the actual message
   var aElem = $('<button></button>'); // Button to view the detailed error log
   var paragraph = $('<p></p>'); // Contain the whole statement
   var divElem; // Contain the detailed error log
   spanMess.text(data.smallMessage);
   spanElem.text(data.type.toUpperCase() + ':');
   paragraph.append(spanElem);
   paragraph.append(spanMess);
   divElem.text(data.largeMessage);
   paragraph.append(aElem);
   paragraph.append(divElem);
   $('#buildLog').append(paragraph); // Div containing all the log messages
};

This is how the logs look on the client side. They are loaded on the go in real time as and when the events occur.

image (1).jpg

Resources:

Implementing Tracks Filter in Open Event Webapp using the side track name list

4f451d29-c6c2-44be-9ef7-d91a45fc1eb0.png

On Clicking the Design, Art, Community Track

ff85d907-512b-4a41-be49-888bbd17bf83.png

But, it was not an elegant solution. We already had a track names list present on the side of the page which remained unused. A better idea was to use this side track names list to filter the sessions. Other event management sites like http://sched.org follow the same idea. The relevant issue for it is here and the major work can be seen in this Pull Request. Below is the screenshot of the unused side track names list.

5b15a297-fd5e-4c23-bc1b-dbed193db0f4.png

The end behavior should be something like this, the user clicks on a track and only sessions belonging to the track should be visible and the rest be hidden. There should also be a button for clearing the applied filter and reverting the page back to its default view. Let’s jump to the implementation part.

First, we make the side track name list and make the individual tracks clickable.

<div class="track-names col-md-3 col-sm-3"> 
  {{#tracknames}}
    <div class="track-info">
      <span style="background-color: {{color}};" 
      class="titlecolor"></span>
      <span class="track-name" style="cursor: pointer">{{title}}
      </span>
    </div>
  {{/tracknames}}
</div>

f45f1591-937d-4e2f-9245-237cfaf3af0d.png

Now we need to write a function for handling the user click event on the track name. Before writing the function, we need to see the basic structure of the tracks page. The divs with the class date-filter contain all the sessions scheduled on a given day. Inside that div, we have another div with class tracks-filter which contains the name of the track and all the sessions of that track are inside the div with class room-filter.

Below is a relevant block of code from the tracks.hbs file

<div class="date-filter">
  // Contains all the sessions present in a single day
  <div class="track-filter row">
    // Contains all the sessions of a single track
    <div class="row">
      // Contains the name of the track
      <h5 class="text">{{caption}}</h4>
    </div>
    <div class="room-filter" id="{{session_id}}">
      // Contain the information about the session
    </div>
  </div>
</div>

We iterate over all the date-filter divs and check all the track-filter divs inside it. We extract the name of the track and compare it to the name of the track which the user selected. If both of them are same, then we show that track div and all the sessions inside it. If the names don’t match, then we hide that track div and all the content inside it. We also keep a variable named flag and set it to 0 initially. If the user selected track is present on a given day, we set the flag to 1. Based on it, we decide whether to display that particular day or not. If the flag is set, we display the date-filter div of that day and the matched track inside it. Otherwise, we hide the div and all tracks inside it.

$('.track-name').click(function() {
  // Get the name of the track which the user clicked
  trackName = $(this).text();
  // Show the button for clearing the filter applied and reverting to the default view
  $('#filterInfo').show();
  $('#curFilter').text(trackName);
  // Iterate through the divs and show sessions of user selected track
  $('.date-filter').each(function() {
    var flag = 0;
    $(this).find('.track-filter').each(function() {
      var name = $(this).find('.text').text();
      if(name != trackName) {
        $(this).hide();
        return;
      }
      flag = 1;
      $(this).show();
    });
    if (flag) {
     $(this).show();
    } else {
      $(this).hide();
    }
  });
});

On Selecting the Android Track of FOSSASIA Summit, we see something like this

935f208b-c17c-4d41-abb6-7197c003d962.png

Now the user may want to remove the filter. He/she can just click on the Clear Filter button shown in the above screenshot to remove the filter and revert back to the default view of the page.

$('#clearFilter').click(function() {                                                                                                   
  trackFilterMode = 0;                                                                                                                 
  display();                                                                                                                           
  $('#filterInfo').hide();                                                                                                             
});

Back to the default view of the page

2ff61ccf-17cf-4595-9c2f-e6825de549f7.png

References:

Open Event Server: No (no-wrap) Ellipsis using jquery!

Yes, the title says it all i.e., Enabling multiple line ellipsis. This was used to solve an issue to keep Session abstract view within 200 characters (#3059) on FOSSASIA‘s Open Event Server project.

There is this one way to ellipsis a paragraph in html-css and that is by using the text-overflow property:

.div_class{
white-space: nowrap;
overflow: hidden;
text-overflow: ellipsis;
}’’

But the downside of this is the one line ellipis. Eg: My name is Medozonuo. I am…..

And here you might pretty much want to ellipsis after a few characters in multiple lines, given that your div space is small and you do want to wrap your paragraph. Or maybe not.

So jquery to the rescue.

There are two ways you can easily do this multiple line ellipsis:

1) Height-Ellipsis (Using the do-while loop):

//script:
if ($('.div_class').height() > 100) {
    var words = $('.div_class').html().split(/\s+/);
    words.push('...');

    do {
        words.splice(-2, 1);
        $('.div_class').html( words.join(' ') );
    } while($('.div_class').height() > 100);
}

Here, you check for the div content’s height and split the paragraph after that certain height and add a “…”, do- while making sure that the paragraphs are in multiple lines and not in one single line. But checkout for that infinite loop.

2) Length-Ellipsis (Using substring function):  

//script:
$.each($('.div_class'), function() {
        if ($(this).html().length > 100) {
               var cropped_words = $(this).html();
               cropped_words = cropped_words.substring(0, 200) + "...";
               $(this).html(cropped_words);
        }
 });

Here, you check for the length/characters rather than the height, take in the substring of the content starting from 0-th character to the 200-th character and then add in extra “…”.

This is exactly how I used it in the code.

$.each($('.short_abstract',function() {
   if ($(this).html().length > 200) {
       var  words = $(this).html();
       words = words.substring(0,200 + "...";
       $(this).html(words);
    }
});


So ellipsing paragraphs over heights and lengths can be done using jQuery likewise.

KISS Datatable

Recenlty I’ve faced a problem with sorting columns in Datatable.

What is Datatable?

Datatable is a plug-in for Jquery library. It provides a lot of features like pagination, quick search or multi-column ordering. Besides, you can develop easily Bootstrap or Foundation ui css styles. There are also more other option but It doesn’t make sense to list it here, because you can visit their site and you can read clearly documentation. On Datatable website you can see a lot of examples. First of them shows how to improve your ordinary table to awesome and rich of features table. One function changes everything, It’s fantastic!  

$('#myTable').DataTable();

Returning to my problem which I’ve faced, as I told it was problem related to sorting column in table.

I know sorting is a trivial thing. I hope that everyone knows it 🙂 Sorting by a date is also implemented in a datatable library. So everything is clear when we don’t change date format to human readable format. I mean something like this ‘3 hours ago’, ‘1 year ago’.

When Open Event team tested how datatable manages ordering columns in that format it didn’t work. It’s quite hard to sort by that format, So I’ve invented an idea. Surely you are wondering what i’ve invented. I’ve postponed my minds about sort by this values. It can direct to overwork. When I thought about it, weird ideas came to my mind, a lots of conditions, If statements… Therefore I’ve resigned from this. I’ve used KISS principle. KISS means ‘keep it simple stupid’. I like it!

Therefore that sorting is implemented on frontend side. I’ve decided not to display human readable date format at the beginning. I find  all dates which have format “YYYY-MM-DD HH:mm” then I replace that format to human readable format. So it’s very quick and comfortable, and doesn’t require a lot conditions to write. Of course I’ve tried to implement it in Datatable library. I suppose that it would  require more effort than it’s now.

Below You can see great function which changes a date in frontend side but does not change data in a datatable. So sorting process takes place in a datatable using format  “YYYY-MM-DD HH:mm” but user see human readable format. Isn’t it awesome?!

function change_column_time_to_humanize_format(datatable_name, column_id) {
  $(datatable_name).each(function( key, value ) {
    $(value).children().each(function( key1, value2 ) {
       if(key1 === column_id ){
          var current_value = $(value2).text().slice(0, 16);
          var changed_value = moment(current_value, "YYYY-MM-DD hh:mm").fromNow()
          var isValid = moment(current_value, "YYYY-MM-DD HH:mm", true).isValid()
          if (changed_value !== current_value && isValid === true){
              $(value2).text(changed_value)
          }
      }
  });
});