Opening Orga App through Intent in Open Event Android App

In the Open Event Android App there is a section called “Manage events”, we direct the users to the Organizer’s app if the users have the app already installed otherwise we open the organizer’s app in the playstore. This way users are motivated to create events using the organizer’s app. Let’s see how this feature was implemented.

So when the user clicks on the menu item “Manage Events” startOrgaApp function is called with the package name of the organizer’s app as the argument. Android apps are uniquely identified by their package names in the playstore.

override fun onOptionsItemSelected(item: MenuItem?): Boolean {

when (item?.getItemId()) {
R.id.orgaApp -> {
startOrgaApp("org.fossasia.eventyay")
return true
}
}

 

Let’s have a look at the startOrgaApp function that we are calling above. We are using a try/catch block here. We are opening the app in the try block if it is installed otherwise we throw ActivityNotFoundException and if this exception happens we will catch it and use the showInMarket function to show the Organizer’s app in the market.

private fun startOrgaApp(packageName: String) {
val manager = activity?.packageManager
try {
val intent = manager?.getLaunchIntentForPackage(packageName)
?: throw ActivityNotFoundException()
intent.addCategory(Intent.CATEGORY_LAUNCHER)
startActivity(intent)
} catch (e: ActivityNotFoundException) {
showInMarket(packageName)
}
}

 

Now since we know this will never raise an exception there is no try catch block as the app with this package name will always be there. We just need to create an intent with the required parameters and then just pass the intent to startActivity

private fun showInMarket(packageName: String) {
val intent = Intent(Intent.ACTION_VIEW, Uri.parse("market://details?id=$packageName"))
intent.flags = Intent.FLAG_ACTIVITY_NEW_TASK
startActivity(intent)
}

 

Lastly we just need to add the XML code to create a menu item. It should contain the id so that we can reference it and the title that will be visible.

<group android:id="@+id/profileMenu">
<item
android:id="@+id/orgaApp"
android:title="@string/manage_events" />
</group>

 

That’s it now you can open an app in the playstore if it is not installed or just open the app if the user has already installed the app.  

Resources

  1. Vogella Intent tutorial – http://www.vogella.com/tutorials/AndroidIntent/article.html
  2. Official Android Documentation Intent – https://developer.android.com/guide/components/intents-filters
  3. Javatpoint intent tutorial – https://www.javatpoint.com/android-explicit-intent-example
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Demystifying a travis.yml file

In this blog post, we are going to demystify a travis.yml file. For reference, we will be using the travis configuration used in the  SUSI skill CMS project. But before delving into it, I would like to just give a brief introduction about Continuous Integration (CI) and Travis CI.

What is CI and Travis ?

Continuous Integration represents the practice of integrating a piece of work as early as possible instead of later so that one can receive immediate and frequent feedback on things that are wrong.

“ Continuous Integration is the practice of merging all developer working copies to a shared mainline several times a day.

-Wikipedia

Travis CI is a hosted continuous integration platform that is free for all open source projects hosted on Github. With just a file called .travis.yml containing some information about our project, we can trigger automated builds with every change to our code base in the master branch, other branches or even a pull request.

sudo: required
dist: trusty
language: node_js

node_js:
  - 6

script:
  - npm test

after_success:
 - bash ./pr_deploy.sh
 - bash ./deploy.sh

cache:
  directories:
    - node_modules

branches:
  only:
    - master

Travis configuration file of susi_skill_cms

Part-wise explanation of the file

  • When specifying sudo: required, Travis CI runs each build in an isolated Google Compute Engine virtual machine that offer a vanilla build environment for every build. This has the advantage that no state persists between builds, offering a clean slate and making sure that the tests run in an environment built from scratch. Builds have access to a variety of services for data storage and messaging, and can install anything that’s required for them to run.
  • The keyword dist represents the virtualization environment that is being used. trusty here refers to the distribution of the Linux environment used.
  • The keyword language represents the programming language that is be used for the project. The language used for the project is nodeJs.
  • Then follows the version details of node_js that is to be used. The node_js version used is 6.
  • This is the step where Travis runs the test script. Unless otherwise specified, it runs the default for the set language. In the case of node, it does node_js. The script stands for the build script that would be executed during the build process. The default build script for nodeJs is npm test. The result of execution of npm test can be found from the package.json file. It executes the npm run lint && react-scripts test –env=jsdom command, which is responsible for checking the linting issues and runs various unit and snapshot tests. We can add multiple lines of command to be executed.
  • The after_success block runs after the entire script is done. It’s the last step in the normal build process has been executed successfully. It has 2 commands to be executed –
    • bash ./pr_deploy.sh : Responsible for making a surge deployment of each PR
    • bash ./deploy.sh : Responsible for making a deployment to master branch
  • Travis CI can cache content that does not often change, to speed up the build process. The cache setting caches the node_modules directory, without the need to install the dependencies repeatedly.
  • We can specify certain branches to run, either by specifying a white list (using only keyword) or a black list (using except keyword). Here, the configuration mentions to run the build only for PRs to master branch.

Resources

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Persisting Cookies over SUSI.AI Subdomains

In this blog post, we are going to see, how the cookies are persisted for all the subdomains of SUSI.AI. By this implementation, the session for the user is maintained over all the SUSI.AI websites.

The cookies are persisted over these SUSI.AI websites –

All the web clients are developed using ReactJs framework and for the manipulation of cookies in React, a npm package – universal-cookie is used. Firstly, we will see how the cookies are set/created during login, followed by removal of cookies during logout.

Creating cookies

  • Firstly, we need to import the universal-cookie package into the component and create an instance of it.
import Cookies from 'universal-cookie';
const cookies = new Cookies();

Now, we can set a new cookie using this instance of cookies.

  • The following snippet sets the cookies after the login is done.

// AJAX call for login

let email = this.state.email.trim();
$.ajax({
  url: loginEndpoint,
  dataType: 'jsonp',
  jsonp: 'callback',
  crossDomain: true,
  success: function(response) {
  if (response.accepted) {
    cookies.set('serverUrl', BASE_URL, {
      path: '/',
      domain: '.susi.ai',
    });
    let accessToken = response.access_token;
    let state = this.state;
    let time = response.valid_seconds;
    this.handleOnSubmit(email, accessToken, time);
  }.bind(this),
  error: function(errorThrown) {
    .
    .
    .
  }.bind(this)    
});

handleOnSubmit = (email, loggedIn, showAdmin, time) => {
  let state = this.state;
  if (state.success) {
    cookies.set('loggedIn', loggedIn, {
      path: '/',
      maxAge: time,
      domain: '.susi.ai',
    });
    cookies.set('emailId', this.state.email, {
      path: '/',
      maxAge: time,
      domain: '.susi.ai',
    });
    this.props.history.push('/', { showLogin: false });
    window.location.reload();
  } else {
    this.setState({
      error: true,
      accessToken: '',
      success: false,
    });
  }
};

 

  • The cookies.set is a function provided by the package, that takes in three (3) parameters –
    • Cookie name
    • Cookie vallue
    • Options – an object containing the cookies properties
  • In the above example, say setting the loggedIn cookie, that contains the access token. We set the cookie name as loggedIn, the cookie value equal to the access token value received from the server response.
  • Apart from that, we have set 3 properties of the cookies, by passing an optional options parameter to the set function.
    • path – It indicates a URL path that must exist in the requested URL in order to send the Cookie header.
    • domainIt specifies allowed hosts to receive the cookie. If unspecified, it defaults to the host of the current document location, excluding subdomains.
    • maxAgeIt specifies a time duration after which the cookie gets expired.

Deleting cookies

  • It is mainly used, when a user wants to logout. It is used in the Logout component of the client’s codebase.
  • An approach to delete/remove a cookie is to set the expiry date of the cookie as Thu, 01 Jan 1970 00:00:01 GMT, which results in the removal of the cookie after a page refresh.
  • Following is the code snippet of how the cookies are removed to log-out a user of the website.

.
.
.
let deleteCookie = function(name, options = {}) {
  let cookieString = `${name}=;expires=Thu, 01 Jan 1970 00:00:01 GMT;`;
  if (options.domain) {
    cookieString = `${cookieString}domain=${options.domain};`;
  }
  if (options.path) {
    cookieString = `${cookieString}path=${options.path};`;
  }
  document.cookie = cookieString;
};
.
.
.
.
deleteCookie('loggedIn', { domain: '.susi.ai', path: '/' });
deleteCookie('serverUrl', { domain: '.susi.ai', path: '/' });
deleteCookie('emailId', { domain: '.susi.ai', path: '/' });
deleteCookie('showAdmin', { domain: '.susi.ai', path: '/' });
deleteCookie('username', { domain: '.susi.ai', path: '/' });

 

  • The deleteCookie function takes in 2 params –
    • Cookie name
    • options – an object containing the cookies properties
  • The options parameter needs to be passed while deleting the cookie, as it defines the scope for which the cookie has to be deleted.
  • The function creates a string and appends to it the expiry date, path, domain to the cookie name, if provided.
  • Finally, it sets the cookie by assigning the string to the document object.

Resources

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Adding a Horizontally scrollable component to display Skills based on metrics

In this blog post, I will discuss about the implementation of a horizontally scrollable component to display skill based on metrics. The purpose of the implementation is to show top skills based on metrics related to usage, ratings, etc in SUSI.AI Skills CMS.

Implementational details

  • We call this component SkillCardScrollList which takes in a list of cards to be displayed along with some other properties and returns an UI, as shown in the above GIF.
  • The parameters that the component takes are:
    • scrollId: It is a required field of the type String. It is the id name of the horizontally scrollable div.
    • skills: It contains an array of cards that are to displayed inside the container.
    • languageValue: It represents the language of the skills that are shown.
    • skillUrl: It contains the URL that the app would be taken to, on clicking individual Skill Card.
    • modelValue: It contains the model that the skill belongs to.
  • Here is a sample of how it is used in the BrowseSkill component, for showing the Top Rated Skills in a SkillCardsScrollList
<SkillCardScrollList
    scrollId="topRated"
    skills={this.state.topRatedSkills}
    modalValue={this.state.modalValue}
    languageValue={this.state.languageValue}
    skillUrl={this.state.skillUrl}
/>

 

  • The reason behind passing an unique scrollId as a prop to the component is that, there was a need to trigger the scroll event of the scrollable div n the click of left and right Floating Action Buttons (FABs) as shown in the UI. And, on multiple imports of this component, there would have been inconsistent scroll behaviour seen, had it not been unique.
  • Following in the code block of the component, which will be explained in details, that deals with the main implementation –
.
.
.
.
  scrollLeft = () => {
    let parentEle = document.getElementById(this.props.scrollId);
    let scrollValue = $(parentEle).scrollLeft() - 200;
    $(parentEle)
      .stop()
      .animate({ scrollLeft: scrollValue }, 100);
  };

  scrollRight = () => {
    // Similar function of scrollLeft
  };

  loadSkillCards = () => {
    let cards = [];
    Object.keys(this.state.skills).forEach(el => {
      .
      /* Each skill object is passed and then pushed to the cards
        array*/
      .
      );
    });
    // Set the cards array in the state 
    this.setState({
      cards,
    });
  };

  render() {
    return (
      <div
        style={{
          marginTop: '20px',
          marginBottom: '40px',
          textAlign: 'justify',
          fontSize: '0.1px',
          width: '100%',
        }}
      >
        <div>
          <div
            id={this.props.scrollId}
            className="scrolling-wrapper"
            style={styles.gridList}
          >
            <FloatingActionButton
              mini={true}
              backgroundColor={'#4285f4'}
              style={styles.leftFab}
              onClick={this.scrollLeft}
            >
              <NavigationChevronLeft />
            </FloatingActionButton>
            {this.state.cards}
            <FloatingActionButton
              mini={true}
              backgroundColor={'#4285f4'}
              style={styles.rightFab}
              onClick={this.scrollRight}
            >
              <NavigationChevronRight />
            </FloatingActionButton>
          </div>
        </div>
      </div>
    );
  }
}

 

  • The div with class scrolling-wrapper is actually scrolled on the click of the left and right FAB. For choosing the correct div to be scrolled, there was a necessary condition of an unique id as explained earlier, which has been set to the div.
  • For making the component horizontally scrollable, specific CSS rules are added to the div. They are –
gridList: {
  margin: '10px',
  textAlign: 'center',
  overflowX: 'scroll',
  overflowY: 'hidden',
  whiteSpace: 'nowrap',
},
leftFab: {
  position: 'absolute',
  left: 260,
  marginTop: 75,
},
rightFab: {
  position: 'absolute',
  right: 0,
  marginTop: 75,
  marginRight: 10,
},

 

  • The CSS rules for the FABs make them fixed in a position and only lets the card list scroll.
  • Lastly, there was a issue regarding the presence of horizontal scroll-bar been shown, which makes the UI look a bit unpleasant.

  • It was hidden with a pseudo selector CSS rule.
div.scrolling-wrapper::-webkit-scrollbar {
    display: none;
}

 

This was the implementation for the horizontally scrollable component for displaying Skill List based on a standard metrics. I hope, you found the blog helpful in making the understanding of the implementation better.

Resources

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Open Event Server – Export Event as a Pentabarf XML File

FOSSASIA‘s Open Event Server is the REST API backend for the event management platform, Open Event. Here, the event organizers can create their events, add tickets for it and manage all aspects from the schedule to the speakers. Also, once he makes his event public, others can view it and buy tickets if interested.

To make event promotion easier, we also provide the event organizer to export his event as a Pentabarf XML file. Pentabarf XML is used to store events/conferences in a format which most of the scheduling applications can read and add that particular event/conference to the user’s schedule.

Server side – generating the Pentabarf XML file

Here we will be using the pentabarf package for Python for parsing and creating the file.

from pentabarf.Conference import Conference
from pentabarf.Day import Day
from pentabarf.Event import Event
from pentabarf.Person import Person
from pentabarf.Room import Room
  • We define a class PentabarfExporter which has a static method export(event_id).
  • Query the event using the event_id passed and start forming the event in the required format:
event = EventModel.query.get(event_id)
diff = (event.ends_at - event.starts_at)

conference = Conference(title=event.name, start=event.starts_at, end=event.ends_at,
                       days=diff.days if diff.days > 0 else 1,
                       day_change="00:00", timeslot_duration="00:15",
                       venue=event.location_name)
dates = (db.session.query(cast(Session.starts_at, DATE))
        .filter_by(event_id=event_id)
        .filter_by(state='accepted')
        .filter(Session.deleted_at.is_(None))
        .order_by(asc(Session.starts_at)).distinct().all())
  • We have queried for the dates of the event and saved it in dates.
  • We will now iterate over each date and query the microlocations who have a session on that particular date.
for date in dates:
   date = date[0]
   day = Day(date=date)
   microlocation_ids = list(db.session.query(Session.microlocation_id)
                            .filter(func.date(Session.starts_at) == date)
                            .filter_by(state='accepted')
                            .filter(Session.deleted_at.is_(None))
                            .order_by(asc(Session.microlocation_id)).distinct())
  • For each microlocation thus obtained, we will query for accepted sessions to be held at those microlocations.
  • We will also initialize a Room for each microlocation.
for microlocation_id in microlocation_ids:
   microlocation_id = microlocation_id[0]
   microlocation = Microlocation.query.get(microlocation_id)
   sessions = Session.query.filter_by(microlocation_id=microlocation_id) \
       .filter(func.date(Session.starts_at) == date) \
       .filter_by(state='accepted') \
       .filter(Session.deleted_at.is_(None)) \
       .order_by(asc(Session.starts_at)).all()

   room = Room(name=microlocation.name)
  • We will now iterate over the aabove-obtained sessions and instantiate an Event for each session.
  • Then we will iterate over all the speakers of that session and instantiate a Person for each speaker.
  • Finally, we will add that Event to the Room we created earlier.
for session in sessions:

   session_event = Event(id=session.id,
                         date=session.starts_at,
                         start=session.starts_at,
                         duration=str(session.ends_at - session.starts_at) + "00:00",
                         track=session.track.name,
                         abstract=session.short_abstract,
                         title=session.title,
                         type='Talk',
                         description=session.long_abstract,
                         conf_url=url_for('event_detail.display_event_detail_home',
                                          identifier=event.identifier),
                         full_conf_url=url_for('event_detail.display_event_detail_home',
                                               identifier=event.identifier, _external=True),
                         released="True" if event.schedule_published_on else "False")

   for speaker in session.speakers:
       person = Person(id=speaker.id, name=speaker.name)
       session_event.add_person(person)

   room.add_event(session_event)
  • Then we will add the room to the day and then add each day to the conference.
day.add_room(room)
conference.add_day(day)
  • Finally, we will call the generate method of the conference to generate the XML file. This can be directly written to the file.
return conference.generate("Generated by " + get_settings()['app_name'])

Obtaining the Pentabarf XML file:

Firstly, we have an API endpoint which starts the task on the server.

GET - /v1/events/{event_identifier}/export/pentabarf

Here, event_identifier is the unique ID of the event. This endpoint starts a celery task on the server to export the event as a Pentabarf XML file. It returns the task of the URL to get the status of the export task. A sample response is as follows:

{
  "task_url": "/v1/tasks/b7ca7088-876e-4c29-a0ee-b8029a64849a"
}

The user can go to the above-returned URL and check the status of his Celery task. If the task completed successfully he will get the download URL. The endpoint to check the status of the task is:

and the corresponding response from the server –

{
  "result": {
    "download_url": "/v1/events/1/exports/http://localhost/static/media/exports/1/zip/OGpMM0w2RH/event1.zip"
  },
  "state": "SUCCESS"
}

The file can be downloaded from the above-mentioned URL.

Hence, now the event can be added to any scheduling app which recognizes the Pentabarf XML format.

References

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Open Event Server – Export Event as xCalendar File

FOSSASIA‘s Open Event Server is the REST API backend for the event management platform, Open Event. Here, the event organizers can create their events, add tickets for it and manage all aspects from the schedule to the speakers. Also, once he makes his event public, others can view it and buy tickets if interested.

To make event promotion easier, we also provide the event organizer to export his event as an xCalendar file. xCal is an XML representation of the iCalendar standard. xCal is not an alternative nor next generation of iCalendar. xCal represents iCalendar components, properties, and parameters as defined in iCalendar. This format was selected to ease its translation back to the iCalendar format using an XSLT transform.

Server side – generating the xCal file

Here we will be using the xml.etree.ElementTree package for Python for parsing and creating XML data.

from xml.etree.ElementTree import Element, SubElement, tostring
  • We define a class XCalExporter which has a static method export(event_id).
  • Query the event using the event_id passed and start forming the calendar:
event = Event.query.get(event_id)

tz = event.timezone or 'UTC'
tz = pytz.timezone(tz)

i_calendar_node = Element('iCalendar')
i_calendar_node.set('xmlns:xCal', 'urn:ietf:params:xml:ns:xcal')
v_calendar_node = SubElement(i_calendar_node, 'vcalendar')
version_node = SubElement(v_calendar_node, 'version')
version_node.text = '2.0'
prod_id_node = SubElement(v_calendar_node, 'prodid')
prod_id_node.text = '-//fossasia//open-event//EN'
cal_desc_node = SubElement(v_calendar_node, 'x-wr-caldesc')
cal_desc_node.text = "Schedule for sessions at " + event.name
cal_name_node = SubElement(v_calendar_node, 'x-wr-calname')
cal_name_node.text = event.name
  • We query for the accepted sessions of the event and store it in sessions
sessions = Session.query \
   .filter_by(event_id=event_id) \
   .filter_by(state='accepted') \
   .filter(Session.deleted_at.is_(None)) \
   .order_by(asc(Session.starts_at)).all()
  • We then iterate through all the sessions in sessions.
  • If it is a valid session, we instantiate a SubElement and store required details
v_event_node = SubElement(v_calendar_node, 'vevent')

method_node = SubElement(v_event_node, 'method')
method_node.text = 'PUBLISH'

uid_node = SubElement(v_event_node, 'uid')
uid_node.text = str(session.id) + "-" + event.identifier

dtstart_node = SubElement(v_event_node, 'dtstart')
dtstart_node.text = tz.localize(session.starts_at).isoformat()

…. So on
  • We then loop through all the speakers in that particular session and add it to the xCal calendar node object as well.
for speaker in session.speakers:
   attendee_node = SubElement(v_event_node, 'attendee')
   attendee_node.text = speaker.name
  • And finally, the string of the calendar node is returned. This is the xCalendar file contents. This can be directly written to a file.
return tostring(i_calendar_node)

Obtaining the xCal file:

Firstly, we have an API endpoint which starts the task on the server.

GET - /v1/events/{event_identifier}/export/xcal

Here, event_identifier is the unique ID of the event. This endpoint starts a celery task on the server to export the event as an xCal file. It returns the URL of the task to get the status of the export task. A sample response is as follows:

{
  "task_url": "/v1/tasks/b7ca7088-876e-4c29-a0ee-b8029a64849a"
}

The user can go to the above-returned URL and check the status of his Celery task. If the task completed successfully he will get the download URL. The endpoint to check the status of the task is:

and the corresponding response from the server –

{
  "result": {
    "download_url": "/v1/events/1/exports/http://localhost/static/media/exports/1/zip/OGpMM0w2RH/event1.zip"
  },
  "state": "SUCCESS"
}

The file can be downloaded from the above mentioned URL.

Hence, now the event can be added to any scheduling app which recognizes the xcs format.

References

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Improving the JSON file upload structure – Open Event Web app

Open Event Web app generator also allows user to upload JSON file for the event data other than the API endpoint. The generator used the socket connection ID to uniquely identify uploaded files on the server which worked good for a single socket connection but failed for multiple due to overlap of connection IDs which resulted in crashing of web app. The problem is fixed by providing a unique ID to every file uploaded on the server and creating a separate field for uploaded file ID in the request body.

How to add listener for file upload?

A listener for socket ‘file’ event is added in the file app.js, which is triggered when the event namely file is emitted by the socket. The file ID kept unique by introducing a counter for number of files uploaded on the server till now and incrementing the counter subsequently for every new file.

ss(socket).on('file', function(stream, file) {
 generator.startZipUpload(count, socket);
 console.log(file);
 filename = path.join(__dirname, '..', 'uploads/connection-' +    count.toString()) + '/upload.zip';
 count += 1;
 stream.pipe(fs.createWriteStream(filename));
});

 

The procedure named startZipUpload in generator.js is executed when the zip file upload starts which further calls the helper function to make uploads directory on the server.

exports.startZipUpload = function(id, socket) {
 console.log('========================ZIP UPLOAD START\n\n');
 distHelper.makeUploadsDir(id, socket);
 distHelper.cleanUploads(id);
};

Creating uploads directory

Uploads directory is created in the root directory using the file system interfaces, the ID passed as parameter ensures that the file names do not overlap.

makeUploadsDir: function(id, socket) {
 fs.mkdirpSync(uploadsPath + '/connection-' + id.toString());
 socket.emit('uploadsId', id);
}

Embedding uploads ID with the data

After the successful creation of uploads directory and the file, the socket emits the ID of uploaded file through the event uploadsID. The value of ID thus received is embedded in the object namely data along with the other entries in the form.

socket.on('uploadsId', function(data) {
 initialValue = data;
});

function getData(initValue) {
 const data = initValue;
 const formData = $('#form').serializeArray();

 formData.forEach(function(field) {
   if (field.name === 'email') {
     data.email = field.value;
   }
   ....
   ....
   ....
   ....
 
   if (field.name === 'apiVersion') {
     data.apiVersion = field.value;
   }
 });

Resources

 

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Open Event Server – Export Event as an iCalendar File

FOSSASIA‘s Open Event Server is the REST API backend for the event management platform, Open Event. Here, the event organizers can create their events, add tickets for it and manage all aspects from the schedule to the speakers. Also, once he makes his event public, others can view it and buy tickets if interested.

To make event promotion easier, we also provide the event organizer to export his event as an iCalendar file. Going by the Wikipedia definition, iCalendar is a computer file format which allows Internet users to send meeting requests and tasks to other Internet users by sharing or sending files in this format through various methods. The files usually have an extension of .ics. With supporting software, such as an email reader or calendar application, recipients of an iCalendar data file can respond to the sender easily or counter propose another meeting date/time. The file format is specified in a proposed internet standard (RFC 5545) for calendar data exchange.

Server side – generating the iCal file

Here we will be using the icalendar package for Python as the file writer.

from icalendar import Calendar, vCalAddress, vText
  • We define a class ICalExporter which has a static method export(event_id).
  • Query the event using the event_id passed and start forming the calendar:
event = EventModel.query.get(event_id)

cal = Calendar()
cal.add('prodid', '-//fossasia//open-event//EN')
cal.add('version', '2.0')
cal.add('x-wr-calname', event.name)
cal.add('x-wr-caldesc', "Schedule for sessions at " + event.name)
  • We query for the accepted sessions of the event and store it in sessions.
sessions = Session.query \
   .filter_by(event_id=event_id) \
   .filter_by(state='accepted') \
   .filter(Session.deleted_at.is_(None)) \
   .order_by(asc(Session.starts_at)).all()
  • We then iterate through all the sessions in sessions.
  • If it is a valid session, we instantiate an icalendar event and store required details.
event_component = icalendar.Event()
event_component.add('summary', session.title)
event_component.add('uid', str(session.id) + "-" + event.identifier)
event_component.add('geo', (event.latitude, event.longitude))
event_component.add('location', session.microlocation.name or '' + " " + event.location_name)
event_component.add('dtstart', tz.localize(session.starts_at))
event_component.add('dtend', tz.localize(session.ends_at))
event_component.add('email', event.email)
event_component.add('description', session.short_abstract)
event_component.add('url', url_for('event_detail.display_event_detail_home',
                                  identifier=event.identifier, _external=True))
  • We then loop through all the speakers in that particular session and add it to the iCal Event object as well.
for speaker in session.speakers:
   # Ref: http://icalendar.readthedocs.io/en/latest/usage.html#file-structure
   # can use speaker.email below but privacy reasons
   attendee = vCalAddress('MAILTO:' + event.email if event.email else '[email protected]')
   attendee.params['cn'] = vText(speaker.name)
   event_component.add('attendee', attendee)
  • This event_component is then added to the cal object that we created in the beginning.
cal.add_component(event_component)
  • And finally, the cal.to_ical() is returned. This is the iCalendar file contents. This can be directly written to a file.
return cal.to_ical()

Obtaining the iCal file:

Firstly, we have an API endpoint which starts the task on the server.

GET - /v1/events/{event_identifier}/export/ical

Here, event_identifier is the unique ID of the event. This endpoint starts a celery task on the server to export the event as an iCal file. It returns the task of the URL to get the status of the export task. A sample response is as follows:

{
  "task_url": "/v1/tasks/b7ca7088-876e-4c29-a0ee-b8029a64849a"
}

The user can go to the above returned URL and check the status of his Celery task. If the task completed successfully he will get the download URL. The endpoint to check the status of the task is:

and the corresponding response from the server –

{
  "result": {
    "download_url": "/v1/events/1/exports/http://localhost/static/media/exports/1/zip/OGpMM0w2RH/event1.zip"
  },
  "state": "SUCCESS"
}

The file can be downloaded from the above mentioned URL.

Hence, now the event can be added to any scheduling app which recognizes the ics format.

References

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Open Event Frontend – Implement Access Event API via REST API

FOSSASIA‘s Open Event Frontend uses the Open Event Server as the REST API backend. The user can create an event using the Frontend. He can add sessions, tickets speakers etc. and all this updates the database tables in Open Event Server. The server provides certain endpoints for the user to access and/or update the information. It is important that the user is aware of the expected response from the server for his API request. Let’s see how this is displayed in the frontend.

In the event-view page of the frontend, which is accessible to the organizers, there is an Export tab, along with Overview, Tickets, Scheduler, Sessions, Speakers.

This tab has an Access Event Information via REST API section which displays the URL to be used by the user and the expected response. It looks as follows :

The user can choose between various options which he can include or exclude. The GET URL is modified accordingly and the appropriate response is shown to the user.

Example of this –

How is this implemented in Code?

We maintain two variables baseUrl and displayUrl to display the URL. baseUrl is the URL which is common in all requests, ie, till the include tag.

baseUrl: computed('eventId', function() {
 return `${`${ENV.APP.apiHost}/${ENV.APP.apiNamespace}/events/`}${this.get('eventId')}`;
})

displayUrl is the variable which stores the URL being displayed on the webpage. It is initialized to the same as baseUrl.

displayUrl: computed('eventId', function() {
 return `${`${ENV.APP.apiHost}/${ENV.APP.apiNamespace}/events/`}${this.get('eventId')}`;
})

To store the value of the toggle switches we use toggleSwitches as follows:

toggleSwitches: {
 sessions       : false,
 microlocations : false,
 tracks         : false,
 speakers       : false,
 sponsors       : false,
 tickets        : false
}

Whenever any of the switches are toggled, an action checkBox is called. This method updates the value of toggleSwitches, calls the method to update the displayUrl and make the corresponding API request to update the displayed response. The code looks like this :

makeRequest() {
 this.set('isLoading', true);
 this.get('loader')
   .load(this.get('displayUrl'), { isExternal: true })
   .then(json => {
     json = JSON.stringify(json, null, 2);
     this.set('json', htmlSafe(syntaxHighlight(json)));
   })
   .catch(() => {
     this.get('notify').error(this.get('l10n').t('Could not fetch from the server'));
     this.set('json', 'Could not fetch from the server');
   })
   .finally(() => {
     this.set('isLoading', false);
   });
},

buildDisplayUrl() {
 let newUrl = this.get('baseUrl');
 const include = [];

 for (const key in this.get('toggleSwitches')) {
   if (this.get('toggleSwitches').hasOwnProperty(key)) {
     this.get('toggleSwitches')[key] && include.push(key);
   }
 }

 this.set('displayUrl', buildUrl(newUrl, {
   include: include.length > 0 ? include : undefined
 }, true));
},

actions: {
 checkboxChange(data) {
   this.set(`toggleSwitches.${data}`, !this.get(`toggleSwitches.${data}`));
   this.buildDisplayUrl();
   this.makeRequest();
 }
}

The above code uses some utility methods such as buildUrl and this.get(‘loager’).load(). The complete codebase is available here -> Open Event Frontend Repository.

References

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