Creating a Notification in Open Event Android App

It is a good practice to show user a notification for alerts and have their attention for important events they want to remember. Open Event Android app shows notifications for the actions like bookmarks, upcoming events etc. In this blog we learn how to create similar kind of alert notification.

 

Displaying notification after bookmarking a track

NotificationCompat is available as part of the Android Support Library, so the first step is opening your project’s module-level build.gradle file and adding the support library to the dependencies section. First we initialize the notification manager with the context of application so a user can see notification irrespective of where it is in app.

NotificationManager mManager = (NotificationManager) this.getApplicationContext().getSystemService(NOTIFICATION_SERVICE);
int id = intent.getIntExtra(ConstantStrings.SESSION, 0);
String session_date;
Session session = realmRepo.getSessionSync(id);

We then get the info we want to display in the notification from the intent. While adding an action to your notification is optional, the reality is that the vast majority of applications add actions to their notifications. We define a notification action using a PendingIntent. In this instance, we update our basic notification with a PendingIntent.

Intent intent1 = new Intent(this.getApplicationContext(), SessionDetailActivity.class);
intent1.putExtra(ConstantStrings.SESSION, session.getTitle());
intent1.putExtra(ConstantStrings.ID, session.getId());
intent1.putExtra(ConstantStrings.TRACK,session.getTrack().getName());
PendingIntent pendingNotificationIntent = PendingIntent.getActivity(this.getApplicationContext(), 0, intent1, PendingIntent.FLAG_UPDATE_CURRENT);
Bitmap largeIcon = BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher);

We also test the condition for the OS version to display the marker image, see image 1 for reference. The minimum requirement for a notification are:

  • An icon: Create the image you want to use and then add it to you project’s ‘drawable’ folder. Here notification shows bookmark option
  • Title text. You can set a notification’s title either by referencing a string resource, or by adding the text to your notification directly.
  • Detail text. This is the most important part of your notification, so this text must include everything the user needs to understand exactly what they’re being notified about.
int smallIcon = R.drawable.ic_bookmark_white_24dp;
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) smallIcon = R.drawable.ic_noti_bookmark;

String session_timings = String.format("%s - %s",
       DateConverter.formatDateWithDefault(DateConverter.FORMAT_12H, session.getStartsAt()),
       DateConverter.formatDateWithDefault(DateConverter.FORMAT_12H, session.getEndsAt()));
session_date = DateConverter.formatDateWithDefault(DateConverter.FORMAT_DATE_COMPLETE, session.getStartsAt());

Finally we build notification using notification builder having various options to set text style, small icons, big icon etc., see the complete class here,

NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this)
       .setSmallIcon(smallIcon)
       .setLargeIcon(largeIcon)
       .setContentTitle(session.getTitle())
       .setContentText(session_date + "\n" + session_timings)
       .setAutoCancel(true)
       .setStyle(new NotificationCompat.BigTextStyle().bigText(session_date + "\n" + session_timings))
       .setContentIntent(pendingNotificationIntent);
intent1.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP | Intent.FLAG_ACTIVITY_CLEAR_TOP);

mBuilder.setSound(RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION));
mManager.notify(session.getId(), mBuilder.build());

References

Implementing Notifications in Open Event Server

In FOSSASIA’s Open Event Server project, along with emails, almost all actions have necessary user notifications as well. So, when a new session is created or a session is accepted by the event organisers, along with the email, a user notification is also sent. Though showing the user notification is mainly implemented in the frontend site but the content to be shown and on which action to show is strictly decided by the server project.

A notification essentially helps an user to get the necessary information while staying in the platform itself and not needing to go to check his/her email for every action he performs. So unlike email which acts as a backup for the informations, notification is more of an instant thing.

The API

The Notifications API is mostly like all other JSON API endpoints in the open event project. However in Notifications API we do not allow any to send a POST request. The admin of the server is able to send a GET a request to view all the notifications that are there in the system while a user can only view his/her notification. As of PATCH we allow only the user to edit his/her notification to mark it as read or not read. Following is the schema for the API:

class NotificationSchema(Schema):
    """
    API Schema for Notification Model
    """

    class Meta:
        """
        Meta class for Notification API schema
        """
        type_ = 'notification'
        self_view = 'v1.notification_detail'
        self_view_kwargs = {'id': '<id>'}
        self_view_many = 'v1.microlocation_list_post'
        inflect = dasherize

    id = fields.Str(dump_only=True)
    title = fields.Str(allow_none=True, dump_only=True)
    message = fields.Str(allow_none=True, dump_only=True)
    received_at = fields.DateTime(dump_only=True)
    accept = fields.Str(allow_none=True, dump_only=True)
    is_read = fields.Boolean()
    user = Relationship(attribute='user',
                        self_view='v1.notification_user',
                        self_view_kwargs={'id': '<id>'},
                        related_view='v1.user_detail',
                        related_view_kwargs={'notification_id': '<id>'},
                        schema='UserSchema',
                        type_='user'
                        )


The main things that are shown in the notification from the frontend are the
title and message. The title is the text that is shown without expanding the entire notification that gives an overview about the message in case you don’t want to read the entire message. The message however provides the entire detail that is associated with the action performed. The user relationship stores which user the particular notification is related with. It is a one-to-one relationship where one notification can only belong to one user. However one user can have multiple notifications. Another important attribute is the is_read attribute. This is the only attribute that is allowed to be changed. By default, when we make an entry in the database, is_read is set to FALSE. Once an user has read the notification, a request is sent from the frontend to change is_read to TRUE.

The different actions for which we send notification are stored in the models/notification.py file as global variables.

USER_CHANGE_EMAIL = "User email"'
NEW_SESSION = 'New Session Proposal'
PASSWORD_CHANGE = 'Change Password'
EVENT_ROLE = 'Event Role Invitation'
TICKET_PURCHASED = 'Ticket(s) Purchased'
TICKET_PURCHASED_ATTENDEE = 'Ticket(s) purchased to Attendee    '
EVENT_EXPORTED = 'Event Exported'
EVENT_EXPORT_FAIL = 'Event Export Failed'
EVENT_IMPORTED = 'Event Imported'

HTML Templates

The notification title and message that is stored in the database and later served via the Notification API is created using some string formatting HTML templates. We firstly import all the global variables that represent the various actions from the notification model. Then we declare a global dict type variable named NOTIFS which stores all title and messages to be stored in the notification table.

NEW_SESSION: {
        'title': u'New session proposal for {event_name}',
        'message': u"""The event <strong>{event_name}</strong> has received
             a new session proposal.<br><br>
            <a href='{link}' class='btn btn-info btn-sm'>View Session</a>""",
        'recipient': 'Organizer',
    },


This is an example of the contents stored inside the dict. For every action, there is a dict with attributes
title, message and recipient. Title contains the brief overview of the entire notification whereas message contains a more vivid description with proper links. Recipient contains the one who receives the notification. So for example in the above code snippet, it is a notification for a new session created. The notification goes to the organizer. The title and message contains named placeholders which are later replaced by particular values using python’s .format() function.

Notification Helper

Notification helper module contains two main parts :-

  1. A parent function which saves the notification to the table related to the user to whom the notification belongs.
  2. Individual notification helper functions that are used by the APIs to save notification after various actions are performed.

Parent Function

def send_notification(user, action, title, message):
    if not current_app.config['TESTING']:
        notification = Notification(user_id=user.id,
                                    title=title,
                                    message=message,
                                    action=action
                                    )
        save_to_db(notification, msg="Notification saved")
        record_activity('notification_event', user=user, action=action, title=title)


send_notification
() is the parent function which takes as parameters user, action, title and message and stores them in the notification table in the database. The user is the one to whom the notification belongs to, action represents the particular action in an API which triggered the notification. Title and message are the contents that are shown in the frontend in the form of a notification. The frontend can implement it as a dropdown notification like facebook or a desktop notification like gitter or whatsapp. After the notification is saved we also update the activity table with the action that a notification has been saved for a user with the following action and title. Later, the Notification API mentioned in the very beginning of the blog uses this data that is being stored now and serves it as a JSON response.

Individual Functions

Apart from this, we have individual functions that uses the parent function to store notifications particular to a particular actions. For example, we have a send_notif_new_session_organizer() function which is used to save notification for all the organizers of an event that a new session has been added to their particular event. This function is called when a POST request is made in the Sessions API and the data is saved successfully. The function is executed for all the organizers of the event for which the session has been created.

def send_notif_new_session_organizer(user, event_name, link):
    message_settings = MessageSettings.query.filter_by(action=NEW_SESSION).first()
    if not message_settings or message_settings.notification_status == 1:
        notif = NOTIFS[NEW_SESSION]
        action = NEW_SESSION
        title = notif['title'].format(event_name=event_name)
        message = notif['message'].format(event_name=event_name, link=link)

        send_notification(user, action, title, message)


In the above function, we take in 3 parameters, user, event_name and link. The value of the user parameter is used to link the notification to that particular user. Event_name and link are used in the title and message of the notification that is saved in the database. Firstly in the function we check if there is certain message setting which tells that the user doesn’t want to receive notifications related to new sessions being created. If not, we proceed. We get the title and message strings from the NOTIFS dict from the system_notification.py file.

After that, using string formatting we get the actual message. For example,

u'New session proposal for {event_name}'.format(‘FOSSASIA’)

would give us a resulting string of the form:

u'New session proposal for FOSSASIA'

After this, we use this variables and send them as parameters to the send_notification() parent function to save the notification properly.

 

Reference:

Mark Notifications Read on Click

Screenshot from 2016-08-01 07:31:22

Notification has become a really important way of informing users about the various activities related to them in web apps. There are different types of notification such as web app notification, email notification, desktop notification, push notification, etc. We are going to primarily talk about web app notification and mainly about how to mark them as read.

Create Notification

Creating a notification is plain and simple. You have a json or an object which stores the notification message corresponding to a particular activity. Whenever that activity occurs in the backend, you call the send notification module, which adds the information to the database and shows it in the notification page. As simple as that.

Screenshot from 2016-08-01 07:48:08

Marking Notification as Read

The main functioning of this is plain and simple as well. You have a URL, which on getting a request from the user, marks the notification as read in the database. That’s it.

Screenshot from 2016-08-01 07:48:17

We know how to do this using a button or a link. But the question here is how to mark a notification as read on clicking any part of the notification?? The obvious answer is, well, put the entire notification inside an anchor tag and you are done, right? Well, it would work in many cases. But what if the design structure is such that this doesn’t work somehow. Somehow enclosing the notification inside a particular anchor tag doesn’t solve the purpose. What do we do then?

Identify Whether Inside a DIV

The main problem here actually is how to identify whether the click is inside the enclosing div or somewhere else. Once we solve this problem, we can send an ajax request to the mark read URL and our job is done.

Screenshot from 2016-08-01 07:52:58

So, to identify that a click is indeed inside a div, we use the event.target property of the event clicked. The target event property returns the element that triggered the event. So we check whether event.target has the “notification” class in our case. If it does not have the “notification” class we check in all it’s parent nodes. We get the parent nodes using the “parent()” function and check whether any of that has notification. If either of the 2 occurs, we consider that the click is inside the div. And thus mark the notification as read.

Screenshot from 2016-08-01 07:51:09

So, once this is done, we mark the notification as read in the backend and our job is done…