Removing Google Places from FDroid Flavor in Orga App

In the Open Event Orga App one of the libraries used was the Google Places by the Play Services. According to the FDroid inclusion policy, proprietary software such as Google Play Services cannot be included in the project and hence it needs to be removed or another alternatives needs to be found. Following steps were taken to remove the Places API and make sure that it is used only in the playStore version of the app.

Steps

  • Initially we will change the implementation in build.gradle file to playStoreImplementation to make sure that Places API is used in the playStore version.
playStoreImplementation “com.google.android.gms:play-services-places:${versions.play_services}”
  • A class LocationPicker.java is created in the fdroid and playStore directory. In the fdroid directory of the project we need to make sure that there is no implementation for the method launchPicker. Following is the code for this class. There is a method name getPlaces which has the following parameters : Activity and the Intent. It will return the Location object where we pass the the demo values for latitude and longitude and null value for the address string.
public class LocationPicker {

  private final double DEMO_VALUE = 1;

  public boolean launchPicker(Activity activity) {
      //do nothing
      return false;
  }

  @SuppressLint(“RestrictedApi”)
  public Location getPlace(Activity activity, Intent data) {
      return new Location(DEMO_VALUE, DEMO_VALUE, null);
  }

  public boolean shouldShowLocationLayout() {
      return true;
  }
}
  • Now we make the following class Location which will receive parameters from fdroid as well as playStore version. We will include this class in the Create package of events so that it can be shared by both LoactionPicker class of fdroid as well as playstore. The location class will take in 3 parameters i.e latitude, longitude and address. Its a normal POJO class.
public class Location {

  private double latitude;
  private double longitude;
  private CharSequence address;

  public Location(double latitude, double longitude, CharSequence address) {
      this.latitude = latitude;
      this.longitude = longitude;
      this.address = address;
  }

  public double getLatitude() {
      return latitude;
  }

  public double getLongitude() {
      return longitude;
  }

  public CharSequence getAddress() {
      return address;
  }

}
  • Now we need to implement the LocationPicker.java class in playStore directory so we need to implement the Google Places API in this particular class. Following is the implementation of the launchPicker class. We will create an instance of the googleApiAvailabilty and pass the activity context through it. If the places API is present and the connection is successful, new intent is made from where the place is selected.

We include the intent statement in the try block and catch the exceptions in the the catch block.

 

public boolean launchPicker(Activity activity) {
  int errorCode = googleApiAvailabilityInstance.isGooglePlayServicesAvailable(activity);

  if (errorCode == ConnectionResult.SUCCESS) {
      //SUCCESS
      PlacePicker.IntentBuilder builder = new PlacePicker.IntentBuilder();
      try {
          activity.startActivityForResult(builder.build(activity), PLACE_PICKER_REQUEST);
          return true;
      } catch (GooglePlayServicesRepairableException e) {
          Timber.d(e, “GooglePlayServicesRepairable”);
      } catch (GooglePlayServicesNotAvailableException e) {
          Timber.d(“GooglePlayServices NotAvailable => Updating or Unauthentic”);
      }
  }
  return false;
};
  • Finally we modify the code in the EventCreateDetails class as well.

Resources:

  1. Official fdroid website https://f-droid.org/en/
  2. Places API Official documentation https://developers.google.com/places/web-service/autocomplete
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Adding Support for Playing Youtube Videos in SUSI iOS App

SUSI supports very exciting features in chat screen, from simple answer type to complex map, RSS, table etc type responses. Even user can ask SUSI for the image of anything and SUSI response with the image in the chat screen. What if we can play the youtube video from SUSI, we ask SUSI for playing videos and it can play youtube videos, isn’t it be exciting? Yes, SUSI can play youtube videos too. All the SUSI clients (iOS, Android, and Web) support playing youtube videos in chat.

Google provides a Youtube iFrame Player API that can be used to play videos inside the app only instead of passing an intent and playing the videos in the youtube app. iFrame API provide support for playing youtube videos in iOS applications.

In this post, we will see how playing youtube video features implemented in SUSI iOS.

Getting response from server side –

When we ask SUSI for playing any video, in response, we get youtube Video ID in video_play action type. SUSI iOS make use of Video ID to play youtube video. In response below, you can see that we are getting answer action type and in the expression of answer action type, we get the title of the video.

actions:
[
{
type: "answer",
expression: "Playing Kygo - Firestone (Official Video) ft. Conrad Sewell"
},
{
identifier: "9Sc-ir2UwGU",
identifier_type: "youtube",
type: "video_play"
}
]

Integrating youtube player in the app –

We have a VideoPlayerView that handle all the iFrame API methods and player events with help of YTPlayer HTML file.

When SUSI respond with video_play action, the first step is to register the YouTubePlayerCell and present the cell in collectionView of chat screen.

Registering the Cell –

register(_:forCellWithReuseIdentifier:) method registers a class for use in creating new collection view cells.

collectionView?.register(YouTubePlayerCell.self, forCellWithReuseIdentifier: ControllerConstants.youtubePlayerCell)

 

Presenting the YouTubePlayerCell –

Here we are presenting the cell in chat screen using cellForItemAt method of UICollectionView.

if message.actionType == ActionType.video_play.rawValue {
if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: ControllerConstants.youtubePlayerCell, for: indexPath) as? YouTubePlayerCell {
cell.message = message
cell.delegate = self
return cell
}
}

 

Setting size for cell –

Using sizeForItemAt method of UICollectionView to set the size.

if message.actionType == ActionType.video_play.rawValue {
return CGSize(width: view.frame.width, height: 158)
}

In YouTubePlayerCell, we are displaying the thumbnail of youtube video using UIImageView. Following method is using to get the thumbnail of particular video by using Video ID –

  1. Getting thumbnail image from URL
  2. Setting image to imageView
func downloadThumbnail() {
if let videoID = message?.videoData?.identifier {
let thumbnailURLString = "https://img.youtube.com/vi/\(videoID)/default.jpg"
let thumbnailURL = URL(string: thumbnailURLString)
thumbnailView.kf.setImage(with: thumbnailURL, placeholder: ControllerConstants.Images.placeholder, options: nil, progressBlock: nil, completionHandler: nil)
}
}

We are adding a play button in the center of thumbnail view so that when the user clicks play button, we can present player.

On clicking the Play button, we are presenting the PlayerViewController, which hold all the player setups, by overFullScreen type of modalPresentationStyle.

@objc func playVideo() {
if let videoID = message?.videoData?.identifier {
let playerVC = PlayerViewController(videoID: videoID)
playerVC.modalPresentationStyle = .overFullScreen
delegate?.loadNewScreen(controller: playerVC)
}
}

The methods above present the youtube player with giving Video ID. We are using YouTubePlayerDelegate method to autoplay the video.

func playerReady(_ videoPlayer: YouTubePlayerView) {
videoPlayer.play()
}

The player can be dismissed by tapping on the light black background.

Final Output –

Resources –

  1. Youtube iOS Player API
  2. SUSI API Sample Response for Playing Video
  3. SUSI iOS Link
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Open Event Server – Export Speakers as PDF 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/she makes his event public, others can view it and buy tickets if interested.

The organizer can see all the speakers in a very detailed view in the event management dashboard. He can see the statuses of all the speakers. The possible statuses are pending, accepted, and rejected. He/she can take actions such as editing the speakers.

If the organizer wants to download the list of all the speakers as a PDF file, he or she can do it very easily by simply clicking on the Export As PDF button in the top right-hand corner.

Let us see how this is done on the server.

Server side – generating the Speakers PDF file

Here we will be using the pisa package which is used to convert from HTML to PDF. It is a html2pdf converter which uses ReportLab Toolkit, the HTML5lib and pyPdf. It supports HTML5 and CSS 2.1 (and some of CSS 3). It is completely written in pure Python so it is platform independent.

from xhtml2pdf import pisa<

We have a utility method create_save_pdf which creates and saves PDFs from HTML. It takes the following arguments:

  • pdf_data – This contains the HTML template which has to be converted to PDF.
  • key – This contains the file name
  • dir_path – This contains the directory

It returns the newly formed PDF file. The code is as follows:

def create_save_pdf(pdf_data, key, dir_path='/static/uploads/pdf/temp/'):
   filedir = current_app.config.get('BASE_DIR') + dir_path

   if not os.path.isdir(filedir):
       os.makedirs(filedir)

   filename = get_file_name() + '.pdf'
   dest = filedir + filename

   file = open(dest, "wb")
   pisa.CreatePDF(io.BytesIO(pdf_data.encode('utf-8')), file)
   file.close()

   uploaded_file = UploadedFile(dest, filename)
   upload_path = key.format(identifier=get_file_name())
   new_file = upload(uploaded_file, upload_path)
   # Removing old file created
   os.remove(dest)

   return new_file

The HTML file is formed using the render_template method of flask. This method takes the HTML template and its required variables as the arguments. In our case, we pass in ‘pdf/speakers_pdf.html’(template) and speakers. Here, speakers is the list of speakers to be included in the PDF file. In the template, we loop through each item of speakers. We print his name, email, list of its sessions, mobile, a short biography, organization, and position. All these fields form a row in the table. Hence, each speaker is a row in our PDF file.

The various columns are as follows:

<thead>
<tr>
   <th>
       {{ ("Name") }}
   </th>
   <th>
       {{ ("Email") }}
   </th>
   <th>
       {{ ("Sessions") }}
   </th>
   <th>
       {{ ("Mobile") }}
   </th>
   <th>
       {{ ("Short Biography") }}
   </th>
   <th>
       {{ ("Organisation") }}
   </th>
   <th>
       {{ ("Position") }}
   </th>
</tr>
</thead>

A snippet of the code which handles iterating over the speakers’ list and forming a row is as follows:

{% for speaker in speakers %}
   <tr class="padded" style="text-align:center; margin-top: 5px">
       <td>
           {% if speaker.name %}
               {{ speaker.name }}
           {% else %}
               {{ "-" }}
           {% endif %}
       </td>
       <td>
           {% if speaker.email %}
               {{ speaker.email }}
           {% else %}
               {{ "-" }}
           {% endif %}
       </td>
       <td>
           {% if speaker.sessions %}
               {% for session in speaker.sessions %}
                   {{ session.name }}<br>
               {% endfor %}
           {% else %}
               {{ "-" }}
           {% endif %}
       </td>
      …. So on
   </tr>
{% endfor %}

The full template can be found here.

Obtaining the Speakers PDF file:

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

GET - /v1/events/{event_identifier}/export/speakers/pdf

Here, event_identifier is the unique ID of the event. This endpoint starts a celery task on the server to export the speakers of the event as a PDF 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/her Celery task. If the task completed successfully he/she 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.

Resources

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Correct the API for Downloading GitHub Content in SUSI.AI android app

The content from github in the SUSI.AI android app is downloaded through simple links and the data is parsed through them and is used in the app depending upon what needs to be done with that data at that time.

A simple example for this that was used in the app was  :

private val imageLink = “https://raw.githubusercontent.com/fossasia/susi_skill_data/master/models/general/”

Above is the link that is used to download and display the images of the skills in the app. All the api calls that generally take place in SUSI are through the SUSI server, and making the call to display the images for the skills which takes place through the github links should be replaced by making the calls to the SUSI server instead, as this is a terrible programming style, with this style the project cannot be cloned from other developers and it cannot be moved to other repositories.

We see that there was a huge programming style issue present in the android app and hence, it was fixed by adding the API that calls the SUSI server for external source images and removing the existing implementation that downloads the image from github directly.

Below is an example of the link to the API call made in the app that was needed for the request to be made to the SUSI server :

${BaseUrl.SUSI_DEFAULT_BASE_URL}/cms/getImage.png?model=${skillData.model}&language=${skillData.language}&group=${skillData.group}&image=${skillData.image}

The link is displayed in the kotlin string interpolation manner, here is what the actual URL would look like :

https://api.susi.ai/cms/getImage.pngmodel=${skillData.model}&language=${skillData.language}&group=${skillData.group}&image=${skillData.image}

Here the values with ‘$’ symbol are the parameters for the API taken from the SkillData.kt file and are put inside the link so that the image needed can be extracted.

Now, since we use this link to set the images, to avoid the duplicate code, an Object class was made for this purpose. The object class contained two functions, one for setting the image and one for parsing the skilldata object and forming a URL out of it. Here is the code for the object class :

object Utils {

  fun setSkillsImage(skillData: SkillData, imageView: ImageView) {
      Picasso.with(imageView.context)
              .load(getImageLink(skillData))
              .error(R.drawable.ic_susi)
              .fit()
              .centerCrop()
              .into(imageView)
  }

  fun getImageLink(skillData: SkillData): String {
      val link = “${BaseUrl.SUSI_DEFAULT_BASE_URL}/cms/getImage.png?model=${skillData.model}&language=${skillData.language}&group=${skillData.group}&image=${skillData.image}”
              .replace(” “,“%20”)
      Timber.d(“SUSI URI” + link)
      return link
  }
}

setSkillsImage() method sets the image in the ImageView and the getImageLink() method returns the image formed out of the SkillData object.

References

 

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Handle response for API calls to the smart speaker

The SUSI.AI android app has the feature to connect to the smart speaker through the WiFi access point of the smart speaker. This connection takes place without internet and is completely offline and takes place locally between the device and the app.

When the APIs are hit, the parameters are sent to the server and are extracted by the speaker and then stored to perform further actions, but like any other API there is some response sent by the server once the parameters are fetched and only when this response is correctly parsed we show the confirmation that the data was required to be sent to the speaker is successfully done.

The SUSI.AI android app was unable to parse this response and so , every time there was a request made to the speaker the error message was displayed on the screen, just like this :

This is a cropped screenshot of the error message shown.

To handle the response from the local server there was a need to add the response parsing classes in the app, also since the app is written in kotlin the specialised classes for this purpose are already present in kotlin which are specifically for the purpose of handling responses. The data classes are added for the three APIs for the local server that are made, the response class added for the WiFi credentials response is :

data class SpeakerWifiResponse(
      val wifi: String,
      val wifi_ssid: String,
      val wifi_password: String
)

Here the first string by the name of ‘wifi’ is used to display a success message and other two variables are for the ssid and password of the wifi network respectively.

The API that is used to set the configuration of the speaker has the response class as follows  :

data class SpeakerConfigResponse(
      val configuration: String,
      val hotword: String,
      val stt: String,
      val tts: String,
      val wake: String
)

The third API which is used to send the auth credentials to the speaker has the following response class :

data class SpeakerAuthResponse(
      val auth: String,
      val authentication: String,
      val email: String,
      val password: String? = null
)

Now these response classes have the variable name similar to the key values in the JSON response generated by the local server. Due to the similar names to the keys an extra step and extra lines of code are eliminated which had to be added otherwise denoting the “Serializable” values to match the JSON response values.

After these data classes were added the Call<> functions of the retrofit service DeviceApi.java were made of the type of the types of the above data classes , which then were able to successfully parse the response from the local server of the speaker.

So, after this the app to speaker connection was successful and a success message was shown as :

References

 

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Ticket Details in the Open Event Android App

After entering all the attendee details and buying a ticket for an event the user expects to see the ticket so that he can use it later. This is why ticket details are shown in a separate fragment in the Open Event Android App. Let’s see how the tickets fragment was made in the Open Event Android App.

Two things that we require from the previous fragment are the event id and the order identifier so that we show the information related to the event as well as the order.

if (bundle != null) {
id = bundle.getLong(EVENT_ID, -1)
orderId = bundle.getString(ORDERS)
}

 

We are requesting data from the following two endpoints. In the first GET request we are passing the order identifier in the URL and we get the list of attendees from the server. In the second endpoint we simply pass the event identifier and get the event details from the server.

 

@GET("/v1/orders/{orderIdentifier}/attendees")
fun attendeesUnderOrder(@Path("orderIdentifier") orderIdentifier: String): Single<List<Attendee>>

@GET("/v1/events/{eventIdentifier}")
fun getEventFromApi(@Path("eventIdentifier") eventIdentifier: Long): Single<Event>

 

Here we are observing the attendees live data and adding the list of attendees returned from the server to the recyclerview so that we can show the user all the details of the attendees like the first name, last name etc. We then notify the adapter that the list of attendees have been added. In the end we log the number of attendees so that it is easier to debug in case there are any bugs.

orderDetailsViewModel.attendees.observe(this, Observer {
it?.let {
ordersRecyclerAdapter.addAll(it)
ordersRecyclerAdapter.notifyDataSetChanged()
}
Timber.d("Fetched attendees of size %s", ordersRecyclerAdapter.itemCount)
})

 

As mentioned earlier we need the event id and order identifier to show event and attendee related information to the user so here we are using the event id and appending it to the url. We are sending a GET request in a background thread and storing the list of events returned from the server in a mutable live data. In case of any errors we log it and show the error message to the user. Similarly we will use the order identifier to get the list of orders from the server and show it to the user.

compositeDisposable.add(eventService.getEventFromApi(id)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe({
event.value = it
}, {
Timber.e(it, "Error fetching event %d", id)
message.value = "Error fetching event"
}))

 

After fetching the list of attendees and event details, the only thing that we need to do is extract the important information and show it to the user so we pass the order and event objects to the ViewHolder. This can be done simply by using the attendee and event objects and accessing the fields required.

itemView.name.text = "${attendee.firstname} ${attendee.lastname}"
itemView.eventName.text = event?.name
itemView.date.text = "$formattedDate\n$formattedTime $timezone"

 

Resources

  1. ReactiveX official documentation: http://reactivex.io/
  2. Retrofit Android: http://square.github.io/retrofit/
  3. Google Android Developers Recycler View: https://developer.android.com/guide/topics/ui/layout/recyclerview
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Implementing Unscheduled Sessions List for Event Scheduler

Until recently, Open Event Server didn’t allow the storage of unscheduled sessions. However, having the provision of unscheduled sessions was necessary so that event organizers can easily schedule the unscheduled sessions and keep track of them. Also, it allows them to remove scheduled sessions from the scheduler and place them in the unscheduled sessions list, so that they can be scheduled later. Also, since the unscheduled sessions list was also present in Eventyay version 1, it was decided to have the same in version 2.

The first step was to enable the storage of unscheduled sessions on the server. For this, the starts-at and ends-at fields of the session model were modified to be non-required (earlier they were mandatory). Once this change was done, the next step was to fetch the list of unscheduled sessions on the frontend, from the server. Unscheduled sessions were the ones which had the starts-at and ends-at fields as null. Also, the speakers’ details needed to be fetched so that their names can be mentioned along with sessions’ titles, in accordance with Eventyay version 1. Thus, the following were the filter options for the unscheduled sessions’ fetching:

let unscheduledFilterOptions = [
      {
        and: [
          {
            name : 'starts-at',
            op   : 'eq',
            val  : null
          },
          {
            name : 'ends-at',
            op   : 'eq',
            val  : null
          }
        ]
      }
];
 
let unscheduledSessions = await eventDetails.query('sessions', {
      include : 'speakers,track',
      filter  : unscheduledFilterOptions
    });

 

This gave us the list of unscheduled sessions on the frontend appropriately. After this, the next step was to display this list to the event organizer. For this, the scheduler’s Handlebars template file was modified appropriately. The colors and sizes were chosen so that the list looks similar to the one in Eventyay version 1. Also, the Ember add-on named ember-drag-drop was used to make these unscheduled session components draggable, so that they can be ultimately scheduled on the scheduler. After installing this package and making the necessary changes to the project’s package.json file, the component file for unscheduled sessions was modified accordingly to adapt for the draggable components’ UI. This was the final step and completed the implementation of listing unscheduled sessions.

unscheduled_sessions.gif

Resources

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Open Event Frontend – Events Explore Page

This blog illustrates how the events explore page is implemented in the Open Event Frontend web app. The user can land on the events explore page by clicking on Browse Events button in the top panel on the home page, shown by the mouse tip in the following picture.

Here, the user can use the various filter options provided to search for the events as per his requirements, He/she can filter according to categories, sub-categories for each category, event type, and date range. A unique feature here is that the user can pick from the start date range options such as today, tomorrow, this week, this weekend, next week and many more. If neither of these fits his needs he can use custom dates as well. The user can also filter events using event location which is autocompleted using Google Maps API. Thus, searching for events is fast, easy and fun.

Let us see how this has been implemented.

Implementation

The explore routes has a method _loadEvents(params). Here, params is the various query parameters for filtering the events. This method forms the query, sends it to the server and returns the list of events returned by the server. The server uses Flask-REST-JSONAPI. It has a very flexible filtering system. It is completely related to the data layer used by the ResourceList manager. More information about this can be found here.

So, the filters are formed using syntax specified in the link mentioned above. We form an array filterOptions which stores the various filters. The default filter is that the event should be published:

let filterOptions = [
 {
   name : 'state',
   op  : 'eq',
   val  : 'published'
 }
];

Then we check for each filter option and check if it is present or not. If yes then we add it to filterOptions. An example as follows:

if (params.category) {
 filterOptions.push({
   name : 'event-topic',
   op  : 'has',
   val  : {
     name : 'name',
     op : 'eq',
     val : params.category
   }
 });
}

This is repeated for sub_category, event_type, location and start_date and end_date. An event is considered to fulfill the date filter if it satisfies any one of the given conditions:

  • If both start_date and end_date are mentioned:
    • Event start_date is after filter start date and before filter end date.
    • Or, event end date if after filter start date and before filter end date.
    • Or, event start date is before filter start date and event end date date is after filter end date.
  • If only start_date is mentioned, then if the event start date is after filter start date or event end date is after filter start date.

The code to this can be found here. For the date ranges mentioned above(today, tomorrow etc) the start dates and end dates are calculated using the moment.js library and then passed on as params.

The filteredEvents are passed in the route model.

async model(params) {
 return {
   eventTypes     : await this.store.findAll('event-type'),
   eventTopics    : await this.store.findAll('event-topic', { include: 'event-sub-topics' }),
   filteredEvents : await this._loadEvents(params)
 };
}

The variable is set in the controller and any change to the query params is observed for. The method _loadEvents is called whenever the query params change.

setupController(controller, model) {
 this._super(...arguments);
 controller.set('filteredEvents', model.filteredEvents);
 this.set('controller', controller);
},

actions: {
 async queryParamsDidChange(change, params) {
   if (this.get('controller')) {
     this.get('controller').set('filteredEvents', await this._loadEvents(params));
   }
 }
}

The template iterates over the filteredEvents and displays each one in a card.

Resources

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Show Option to choose WiFi for Smart Speaker Connection in SUSI.AI Android APP

SUSI.AI android app has the functionality to detect the available WiFi networks and among them check for the hotspot named “SUSI.AI”. Now, this process is required so that the app can connect to the smart speaker and send the WiFi credentials, the authentication credentials and the configuration data to the smart speaker.

After on clicking the “SET UP” button on the available SUSI.AI hotspot as shown in the image below,

The app needs to make API requests where the app will send the data to the speaker, the first API that needs to be hit is for the WiFi credentials. Once the “SET UP” button is clicked the app shows a message “Connecting to your device” with a loader as in the image below :

Now during this step the code to detect the available WiFi networks is run again and the list of the available networks is sent from the DeviceConnectPresenter.kt to the DeviceConnectFragment.kt from the function defined in the presenter as follows :

override fun availableWifi(list: List<ScanResult>) {
  connections = ArrayList<String>()
  for (i in list.indices) {
      connections.add(list[i].SSID)
  }
  if (!list.isEmpty()) {
      deviceConnectView?.setupWiFiAdapter(connections)
  } else {
      deviceConnectView?.onDeviceConnectionError(utilModel.getString(R.string.no_device_found), utilModel.getString(R.string.setup_tut))
  }
}

Now to show the list of available WiFi networks a new ViewHolder had to made which contained a textview and an imageview. The viewholder file named WifiViewHolder.java is responsible for this and is used along with the DeviceAdapter only.

The interesting thing to see is that the DeviceAdapter already inflates the ViewItems of the type DeviceViewHolder. Instead of making a new adapter for the WifiViewHolder view item, I wrote some smart code that handles both the viewholders with the same adapter i.e DeviceAdapter. Let’s now see how this was handled,

In the DeviceAdapter a private variable named viewCode of type integer was made and it would be responsible to segregate the two viewholders using an if command. Here is code below that shows how using viewcode variable allows us to choose and inflate a viewholder among the two we have in onCreateViewHolder() method :

if (viewCode == 1) {
  View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.device_layout, parent, false);
  return new DeviceViewHolder(v, (DeviceConnectPresenter) devicePresenter);
} else {
  View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.layout_wifi_item, parent, false);
  return new WifiViewHolder(v, (DeviceConnectPresenter) devicePresenter);
}

Now, when the viewholder of type WifiViewHolder is inflated the app displays a list of available wifi networks and on clicking any of the Wifi items the app asks the user to enter the credentials of the WiFi network. Below is how the app looks when the available wifi networks are loaded and displayed and also when we click on any of the item in the list.

References :

  1. Android manipulating Wifi networks using WiFiManager : https://medium.com/@josiassena/android-manipulating-wifi-using-the-wifimanager-9af77cb04c6a
  2. Kotlin broadcast intents and receivers : https://www.techotopia.com/index.php/Kotlin_Android_Broadcast_Intents_and_Broadcast_Receivers
  3. Android Viewholder pattern : https://www.javacodegeeks.com/2013/09/android-viewholder-pattern-example.html
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Open Event Server – Export Sessions as PDF 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/she makes his event public, others can view it and buy tickets if interested.

The organizer can see all the sessions in a very detailed view in the event management dashboard. He can see the statuses of all the sessions. The possible statuses are pending, accepted, confirmed and rejected. He/she can take actions such as accepting/rejecting the sessions.

If the organizer wants to download the list of all the sessions as a PDF file, he or she can do it very easily by simply clicking on the Export As PDF button in the top right-hand corner.

Let us see how this is done on the server.

Server side – generating the Sessions PDF file

Here we will be using the pisa package which is used to convert from HTML to PDF. It is a html2pdf converter which uses ReportLab Toolkit, the HTML5lib and pyPdf. It supports HTML5 and CSS 2.1 (and some of CSS 3). It is completely written in pure Python so it is platform independent.

from xhtml2pdf import pisa

We have a utility method create_save_pdf which creates and saves PDFs from HTML. It takes the following arguments:

  • pdf_data – This contains the HTML template which has to be converted to PDF.
  • key – This contains the file name
  • dir_path – This contains the directory

It returns the newly formed PDF file. The code is as follows:

def create_save_pdf(pdf_data, key, dir_path='/static/uploads/pdf/temp/'):
   filedir = current_app.config.get('BASE_DIR') + dir_path

   if not os.path.isdir(filedir):
       os.makedirs(filedir)

   filename = get_file_name() + '.pdf'
   dest = filedir + filename

   file = open(dest, "wb")
   pisa.CreatePDF(io.BytesIO(pdf_data.encode('utf-8')), file)
   file.close()

   uploaded_file = UploadedFile(dest, filename)
   upload_path = key.format(identifier=get_file_name())
   new_file = upload(uploaded_file, upload_path)
   # Removing old file created
   os.remove(dest)

   return new_file

The HTML file is formed using the render_template method of flask. This method takes the HTML template and its required variables as the arguments. In our case, we pass in ‘pdf/sessions_pdf.html’(template) and sessions. Here, sessions is the list of sessions to be included in the PDF file. In the template, we loop through each item of sessions and check if it is deleted or not. If it not deleted then we print its title, state, list of its speakers, track, created at and has an email been sent or not. All these fields form a row in the table. Hence, each session is a row in our PDF file.

The various columns are as follows:

<thead>
<tr>
   <th>
       {{ ("Title") }}
   </th>
   <th>
       {{ ("State") }}
   </th>
   <th>
       {{ ("Speakers") }}
   </th>
   <th>
       {{ ("Track") }}
   </th>
   <th>
       {{ ("Created At") }}
   </th>
   <th>
       {{ ("Email Sent") }}
   </th>
</tr>
</thead>

A snippet of the code which handles iterating over the sessions list and forming a row is as follows:

{% for session in sessions %}
   {% if not session.deleted_at %}
       <tr class="padded" style="text-align:center; margin-top: 5px">
           <td>
               {% if session.title %}
                   {{ session.title }}
               {% else %}
                   {{ "-" }}
               {% endif %}
           </td>
           <td>
               {% if session.state %}
                   {{ session.state }}
               {% else %}
                   {{ "-" }}
               {% endif %}
           </td>
           <td>
               {% if session.speakers %}
                   {% for speaker in session.speakers %}
                       {{ speaker.name }}<br>
                   {% endfor %}
               {% else %}
                   {{ "-" }}
               {% endif %}
           </td>
          ….. And so on
       </tr>
   {% endif %}
{% endfor %}

The full template can be found here.

Obtaining the Sessions PDF file:

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

GET - /v1/events/{event_identifier}/export/sessions/pdf

Here, event_identifier is the unique ID of the event. This endpoint starts a celery task on the server to export the sessions of the event as a PDF 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/her Celery task. If the task completed successfully he/she 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.

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