Implementing User Email Verification in Open Event Frontend

Open Event Server provides the functionality of user email verification after a user registers, but it was not implemented on Open Event Frontend until recently. For users, this meant they were still not able to verify themselves, even after receiving confirmation links in their inboxes, which were sent by the server. Thus, implementing it on frontend was crucial for a complete user registration workflow.

Since the server had already exposed an endpoint to perform the registration, all that was required on the frontend to be done was to make a call to this endpoint with the necessary data. The entire process can be summarized as follows:

  1. The recently registered user clicks on the verification link she receives on her email
  2. The above step opens the link, which is of the format http://fossasia.github.io/open-event-frontend/verify?token=
  3. As soon as the frontend server receives this request, it extracts the token from the URL query parameter
  4. The token is now sent to the backend server as a patch request
  5. The response of the above request confirms whether the user verification is successful or not, and an appropriate message is displayed

In the frontend code, the above algorithm is spread across 3 files: the router, verify route and verify controller. A new route named /verify was implemented for the user verification, and was registered in the project’s main router.js file. After that, in the verify route, the beforeModel() method is used to trigger the above algorithm before the page is loaded:

// in app/routes/verify.js

beforeModel(transition) {
this.controllerFor('verify').verify(transition.queryParams.token);
}

The main algorithm above is implemented in the verify controller:

// in app/controllers/verify.js
...
queryParams : ['token'],
token       : null,
success     : false,
error       : null,

verify(tokenVal) {
let payload = {
data: {
token: tokenVal
}
};
return this.get('loader')
.post('auth/verify-email', payload)
.then(() => {
this.set('success', true);
})
.catch(reason => {
this.set('error', reason);
this.set('success', false);
});
}
});

 

A template for displaying the success or failure messages to the user was also created. It uses the value of the success boolean set above to decide the message to be displayed to the user. The user registration workflow is now complete and the user sees the following message after clicking on the verification link she receives:

Screen Shot 2018-08-21 at 7.10.43 PM

Resources

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Upgrading Open Event to Use Sendgrid API v3

Sendgrid recently upgraded their web API to send emails, and support for previous versions was deprecated. As a result, Open Event Server’s mail sending tasks were rendered unsuccessful, because the requests they were sending to Sendgrid were not being processed. On top of that, it was also found out later that the existing Sendgrid API key on the development server was expired. This had to be fixed at the earliest because emails are a core part of Open Event functionality.

The existing way for emails to be sent via Sendgrid used to hit the endpoint “https://api.sendgrid.com/api/mail.send.json” to send emails. Also, the payload structure was as follows:

payload = {
    'to': to,
    'from': email_from,
    'subject': subject,
    'html': html
}

Also, a header  “Authorization”: “Bearer ” accompanied the above payload. However, Sendgrid changed the payload structure to be of the following format:

{

“personalizations”: [

{“to”: [

{“email”: “[email protected]“}

]

}

],

“from”: {

“email”: “[email protected]

},

“subject”: “Hello, World!”,

“content”: [

{

“type”: “text/plain”,

“value”: “Heya!”

}

]

}

Furthermore, the endpoint was changed to be “https://api.sendgrid.com/v3/mail/send”. To incorporate all these changes with the minimum number of modified lines in the codebase, it was required for that the structure change itself happens at a fairly low level. This was because there are lots of features in the server that perform a wide variety of email actions. Thus, it was clear that changing all of them will not be the most efficient thing to do. So the perfect place to implement the API changes was the function send_email() in mail.py, because all other higher-level email functions are built on top of this function. But this was not the only change, because this function itself used another function, called send_email_task() in tasks.py, specifically for sending email via Sendgrid. So, in conclusion, the header modifications were made in send_email() and payload structure as well as endpoint modifications were made within send_email_task(). This brought the server codebase back on track to send emails successfully. Finally, the key for development server was also renewed and added to its settings in the Heroku Postgres database.

Screenshots:

Screen Shot 2018-08-21 at 3.40.12 PM.png

Screen Shot 2018-08-21 at 3.40.32 PM.png

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Integrating Gravatar and Anonymizing Email Address in Feedback Section

SUSI skills are having a very nice feedback system that allows the user to rate skills from 1-star to 5-star and showing ratings in skills screens. SUSI also allow the user to post feedback about skills and display them. You can check out how posting feedback implemented here and how displaying feedback feature implemented here. To enhance the user experience, we are adding user gravatar in the feedback section and to respect user privacy, we are anonymizing the user email displayed in the feedback section. In this post, we will see how these features implemented in SUSI iOS.

Integrating Gravatar –

We are showing gravatar of the user before feedback. Gravatar is a service for providing globally-unique avatars. We are using user email address to get the gravatar. The most basic gravatar image request URL looks like this:

https://www.gravatar.com/avatar/HASH

where HASH is replaced with the calculated hash for the specific email address we are requesting. We are using the MD5 hash function to hash the user’s email address.

The MD5 hashing algorithm is a one-way cryptographic function that accepts a message of any length as input and returns as output a fixed-length digest value to be used for authenticating the original message.

In SUSI iOS, we have MD5Digest.swift file that gives the hash value of email string. We are using the following method to set gravatar:

if let userEmail = feedback?.email {
setGravatar(from: userEmail)
}
func setGravatar(from emailString: String) {
let baseGravatarURL = "https://www.gravatar.com/avatar/"
let emailMD5 = emailString.utf8.md5.rawValue
let imageString = baseGravatarURL + emailMD5 + ".jpg"
let imageURL = URL(string: imageString)
gravatarImageView.kf.setImage(with: imageURL)
}

Anonymizing User’s Email Address –

Before the implementation of this feature, the user’s full email address was displayed in the feedback section and see all review screen. To respect the privacy of the user, we are now only showing user email until the `@` sign.

In Feedback object, we have the email address string that we modify to show until `@` sign by following way:

if let userEmail = feedback?.email, let emailIndex = userEmail.range(of: "@")?.upperBound {
userEmailLabel.text = String(userEmail.prefix(upTo: emailIndex)) + "..."
}

 

Final Output –

Resources –

  1. Post feedback for SUSI Skills in SUSI iOS
  2. Displaying Skills Feedback on SUSI iOS
  3. What is MD5?
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Implementing Endpoint to Resend Email Verification

Earlier, when a user registered via Open Event Frontend, s/he received a verification link via email to confirm their account. However, this was not enough in the long-term. If the confirmation link expired, or for some reasons the verification mail got deleted on the user side, there was no functionality to resend the verification email, which prevented the user from getting fully registered. Although the front-end already showed the option to resend the verification link, there was no support from the server to do that, yet.

So it was decided that a separate endpoint should be implemented to allow re-sending the verification link to a user. /resend-verification-email was an endpoint that would fit this action. So we decided to go with it and create a route in `auth.py` file, which was the appropriate place for this feature to reside. First step was to do the necessary imports and then definition:

from app.api.helpers.mail import send_email_confirmation
from app.models.mail import USER_REGISTER_WITH_PASSWORD
...
...
@auth_routes.route('/resend-verification-email', methods=['POST'])
def resend_verification_email():
...

Now we safely fetch the email mentioned in the request and then search the database for the user corresponding to that email:

def resend_verification_email():
    try:
        email = request.json['data']['email']
    except TypeError:
        return BadRequestError({'source': ''}, 'Bad Request Error').respond()

    try:
        user = User.query.filter_by(email=email).one()
    except NoResultFound:
        return UnprocessableEntityError(
{'source': ''}, 'User with email: ' + email + ' not found.').respond()
    else:

    ...

Once a user has been identified in the database, we proceed further and create an essentially unique hash for the user verification. This hash is in turn used to generate a verification link that is then ready to be sent via email to the user:

else:
    serializer = get_serializer()
    hash_ = str(base64.b64encode(str(serializer.dumps(
[user.email, str_generator()])).encode()), 'utf-8')
    link = make_frontend_url(
'/email/verify'.format(id=user.id), {'token': hash_})

Finally, the email is sent:

send_email_with_action(
user, USER_REGISTER_WITH_PASSWORD,
app_name=get_settings()['app_name'], email=user.email)
    if not send_email_confirmation(user.email, link):
        return make_response(jsonify(message="Some error occured"), 500)
    return make_response(jsonify(message="Verification email resent"), 200)

But this was not enough. When the endpoint was tested, it was found that actual emails were not being delivered, even after correctly configuring the email settings locally. So, after a bit of debugging, it was found that the settings, which were using Sendgrid to send emails, were using a deprecated Sendgrid API endpoint. A separate email function is used to send emails via Sendgrid and it contained an old endpoint that was no longer recommended by Sendgrid:

@celery.task(name='send.email.post')
def send_email_task(payload, headers):
   requests.post(
       "https://api.sendgrid.com/api/mail.send.json",
       data=payload,
       headers=headers
   )

The new endpoint, as per Sendgrid’s documentation, is:

https://api.sendgrid.com/v3/mail/send

But this was not the only change required. Sendgrid had also modified the structure of requests they accepted, and the new structure was different from the existing one that was used in the server. Following is the new structure:

'{"personalizations": [{"to": [{"email": "[email protected]"}]}],"from": {"email": "[email protected]"},"subject": "Hello, World!","content": [{"type": "text/plain", "value": "Heya!"}]}'

The header structure was also changed, so the structure in the server was also updated to

headers = {
"Authorization": ("Bearer " + key),
"Content-Type": "application/json"
}

The Sendgrid function (which is executed as a Celery task) was modified as follows, to incorporate the changes in the API endpoint and structure:

import json
...
@celery.task(name='send.email.post')
def send_email_task(payload, headers):
    data = {"personalizations": [{"to": []}]}
    data["personalizations"][0]["to"].append({"email": payload["to"]})
    data["from"] = {"email": payload["from"]}
    data["subject"] = payload["subject"]
    data["content"] = [{"type": "text/html", "value": payload["html"]}]
    requests.post(
        "https://api.sendgrid.com/v3/mail/send",
        data=json.dumps(data),
        headers=headers,
        verify=False  # doesn't work with verification in celery context
    )

 

As can be seen, there is a bug that doesn’t allow SSL verification within the celery context. However, the verification is successful when the functionality is executed independent of the celery context. But now email sending via Sendgrid actually works, which makes our verification resend endpoint functional:Screen Shot 2018-08-10 at 10.04.12 PM.pngEmail is received successfully by the recipient:

Screen Shot 2018-08-10 at 10.04.30 PM.png

Thus, a working email verification endpoint is implemented, which can be easily integrated in the frontend.


Resources:

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Implementation of Features in Generator UI

In the early stage of development, Meilix Generator only has wallpaper and event name customization. But today the webapp has bunch of customization and features list which enables an user to design its own customizable ISO.

Iteration in the form

Meilix Generator came across several changes in the form throughout the time.

At starting we only have an email part where the ISO get mailed, a name for the event so as to distinguish the ISO image and an image upload which will be set as the default desktop wallpaper in the ISO.

Then the user gets a link which get activated after 20 minutes. Till then user have to preserve the link to download the ISO.

Then we introduced a new field which contains event link and this link will be set as the homepage of the browser. And we change the basic UI of the webapp.

At the same we implemented SendGrid to send the user the email link in their mail. This decreases the burden of carrying the downloadable link till the ISO becomes ready.

Finally today Meilix Generator looks like this. It got some more customizable fields like providing default search engine, bookmark enabling or disabling and packages to include in the ISO.

It has a link on the footer from which the latest pre-build ISO can be downloaded instantly and another link which takes user to the releases page of Meilix.

Reference:

SendGrid Email Delivery Service

SendGrid Email API

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Implement Email in Open Event Server

In FOSSASIA’s Open Event Server project, we send out emails when various different actions are performed using the API. For example, when a new user is created, he/she receives an email welcoming him to the server as well as an email verification email. Users get role invites from event organisers in the form of emails, when someone buys a ticket he/she gets a PDF link to the ticket as email. So as you can understand all the important informations that are necessary to be notified to the user are sent as an email to the user and sometimes to the organizer as well.

In FOSSASIA, we use sendgrid’s API or an SMTP server depending on the admin settings for sending emails. You can read more about how we use sendgrid’s API to send emails in FOSSASIA here. Now let’s dive into the modules that we have for sending the emails. The three main parts in the entire email sending are:

  1. Model – Storing the Various Actions
  2. Templates – Storing the HTML templates for the emails
  3. Email Functions – Individual functions for various different actions

Let’s go through each of these modules one by one.

Model

USER_REGISTER = 'User Registration'
USER_CONFIRM = 'User Confirmation'
USER_CHANGE_EMAIL = "User email"
INVITE_PAPERS = 'Invitation For Papers'
NEXT_EVENT = 'Next Event'
NEW_SESSION = 'New Session Proposal'
PASSWORD_RESET = 'Reset Password'
PASSWORD_CHANGE = 'Change Password'
EVENT_ROLE = 'Event Role Invitation'
SESSION_ACCEPT_REJECT = 'Session Accept or Reject'
SESSION_SCHEDULE = 'Session Schedule Change'
EVENT_PUBLISH = 'Event Published'
AFTER_EVENT = 'After Event'
USER_REGISTER_WITH_PASSWORD = 'User Registration during Payment'
TICKET_PURCHASED = 'Ticket(s) Purchased'


In the Model file, named as
mail.py, we firstly declare the various different actions for which we send the emails out. These actions are globally used as the keys in the other modules of the email sending service. Here, we define global variables with the name of the action as strings in them. These are all constant variables, which means that there value remains throughout and never changes. For example, USER_REGISTER has the value ‘User Registration’, which essentially means that anything related to the USER_REGISTER key is executed when the User Registration action occurs. Or in other words, whenever an user registers into the system by signing up or creating a new user through the API, he/she receives the corresponding emails.
Apart from this, we have the model class which defines a table in the database. We use this model class to store the actions performed while sending emails in the database. So we store the action, the time at which the email was sent, the recipient and the sender. That way we have a record about all the emails that were sent out via our server.

class Mail(db.Model):
    __tablename__ = 'mails'
    id = db.Column(db.Integer, primary_key=True)
    recipient = db.Column(db.String)
    time = db.Column(db.DateTime(timezone=True))
    action = db.Column(db.String)
    subject = db.Column(db.String)
    message = db.Column(db.String)

    def __init__(self, recipient=None, time=None, action=None, subject=None,
                 message=None):
        self.recipient = recipient
        self.time = time
        if self.time is None:
            self.time = datetime.now(pytz.utc)
        self.action = action
        self.subject = subject
        self.message = message

    def __repr__(self):
        return '<Mail %r to %r>' % (self.id, self.recipient)

    def __str__(self):
        return unicode(self).encode('utf-8')

    def __unicode__(self):
        return 'Mail %r by %r' % (self.id, self.recipient,)


The table name in which all the information is stored is named as mails. It stores the recipient, the time at which the email is sent (timezone aware), the action which initiated the email sending, the subject of the email and the entire html body of the email. In case a datetime value is sent, we use that, else we use the current time in the time field.

HTML Templates

We store the html templates in the form of key value pairs in a file called system_mails.py inside the helpers module of the API. Inside the system_mails, we have a global dict variable named MAILS as shown below.

MAILS = {
    EVENT_PUBLISH: {
        'recipient': 'Organizer, Speaker',
        'subject': u'{event_name} is Live',
        'message': (
            u"Hi {email}<br/>" +
            u"Event, {event_name}, is up and running and ready for action. Go ahead and check it out." +
            u"<br/> Visit this link to view it: {link}"
        )
    },
    INVITE_PAPERS: {
        'recipient': 'Speaker',
        'subject': u'Invitation to Submit Papers for {event_name}',
        'message': (
            u"Hi {email}<br/>" +
            u"You are invited to submit papers for event: {event_name}" +
            u"<br/> Visit this link to fill up details: {link}"
        )
    },
    SESSION_ACCEPT_REJECT: {
        'recipient': 'Speaker',
        'subject': u'Session {session_name} has been {acceptance}',
        'message': (
            u"Hi {email},<br/>" +
            u"The session <strong>{session_name}</strong> has been <strong>{acceptance}</strong> by the organizer. " +
            u"<br/> Visit this link to view the session: {link}"
        )
    },
    SESSION_SCHEDULE: {
        'recipient': 'Organizer, Speaker',
        'subject': u'Schedule for Session {session_name} has been changed',
        'message': (
            u"Hi {email},<br/>" +
            u"The schedule for session <strong>{session_name}</strong> has been changed. " +
            u"<br/> Visit this link to view the session: {link}"
        )
    },


Inside the MAILS dict, we have key-value pairs, where in keys we use the global variables from the Model to define the action related to the email template. In the value, we again have 3 different key-value pairs – recipient, subject and message. The recipient defines the group who should receive this email, the subject goes into the subject part of the email while message forms the body for the email. For subject and message we use unicode strings with named placeholders that are used later for formatting using python’s
.format() function.

Email Functions

This is the most important part of the entire email sending system since this is the place where the entire email sending functionality is implemented using the above two modules. We have all these functions inside a single file namely mail.py inside the helpers module of the API. Firstly, we import two things in this file – The global dict variable MAILS defined in the template file above, and the various global action variables defined in the model. There is one main module which is used by every other individual modules for sending the emails defined as send_email(to, action, subject, html). This function takes as parameters the email to which the email is to be sent, the subject string, the html body string along with the action to store it in the database.

Firstly we ensure that the email address for the recipient is present and isn’t an empty string. After we have ensured this, we retrieve the email service as set in the admin settings. It can either be “smtp” or “sendgrid”. The email address for the sender has different formatting depending on the email service we are using. While sendgrid uses just the email say for example “[email protected]”, smtp uses a format  a little different like this: Medozonuo Suohu<[email protected]>. So we set that as well in the email_from variable.

def send_email(to, action, subject, html):
    """
    Sends email and records it in DB
    """
    if not string_empty(to):
        email_service = get_settings()['email_service']
        email_from_name = get_settings()['email_from_name']
        if email_service == 'smtp':
            email_from = email_from_name + '<' + get_settings()['email_from'] + '>'
        else:
            email_from = get_settings()['email_from']
        payload = {
            'to': to,
            'from': email_from,
            'subject': subject,
            'html': html
        }

        if not current_app.config['TESTING']:
            if email_service == 'smtp':
                smtp_encryption = get_settings()['smtp_encryption']
                if smtp_encryption == 'tls':
                    smtp_encryption = 'required'
                elif smtp_encryption == 'ssl':
                    smtp_encryption = 'ssl'
                elif smtp_encryption == 'tls_optional':
                    smtp_encryption = 'optional'
                else:
                    smtp_encryption = 'none'

                config = {
                    'host': get_settings()['smtp_host'],
                    'username': get_settings()['smtp_username'],
                    'password': get_settings()['smtp_password'],
                    'encryption': smtp_encryption,
                    'port': get_settings()['smtp_port'],
                }

                from tasks import send_mail_via_smtp_task
                send_mail_via_smtp_task.delay(config, payload)


After this we create the payload containing the email address for the recipient, the email address of the sender, the subject of the email and the html body of the email.
For unittesting and any other testing we avoid email sending since that is really not required in the flow. So we check that the current app is not configured to run in a testing environment. After that we have two different implementation depending on the email service used.

SMTP

There are 3 kind of possible encryptions for the email that can be used with smtp server – tls, ssl and optional. We determine this based on the admin settings again. Also, from the admin settings we collect the host, username, password and port for the smtp server.

After this we start a celery task for sending the email. Since email sending to a number of clients can be time consuming so we do it using the celery queueing service without disturbing the main workflow of the entire system.

@celery.task(name='send.email.post.smtp')
def send_mail_via_smtp_task(config, payload):
    mailer_config = {
        'transport': {
            'use': 'smtp',
            'host': config['host'],
            'username': config['username'],
            'password': config['password'],
            'tls': config['encryption'],
            'port': config['port']
        }
    }

    mailer = Mailer(mailer_config)
    mailer.start()
    message = Message(author=payload['from'], to=payload['to'])
    message.subject = payload['subject']
    message.plain = strip_tags(payload['html'])
    message.rich = payload['html']
    mailer.send(message)
    mailer.stop()

Inside the celery task, we use the Mailer and Message classes from the marrow module of python. We configure the Mailer according to the various settings received from the admin and then use the payload to send the email.

Sendgrid

For sending email using the sendgrid API, we need to set the Bearer key which is used for authenticating the email service. This key is also defined in the admin settings. After we have set the Bearer key as the authorization header, we again initiate the celery task corresponding to the sendgrid email sending service.

@celery.task(name='send.email.post')
def send_email_task(payload, headers):
    requests.post(
        "https://api.sendgrid.com/api/mail.send.json",
        data=payload,
        headers=headers
    )


For sending the email service, all we need to do is make a POST request to the api endpoint “
https://api.sendgrid.com/api/mail.send.json” with the headers which contains the Bearer Key and the data which contains the payload containing all the information related to the recipient, sender, subject of email and the body of the email.

Apart from these, this module implements all the individual functions that are called based on the various functions that occur. For example, let’s look into the email sending function in case a new session is created.

def send_email_new_session(email, event_name, link):
    """email for new session"""
    send_email(
        to=email,
        action=NEW_SESSION,
        subject=MAILS[NEW_SESSION]['subject'].format(
            event_name=event_name
        ),
        html=MAILS[NEW_SESSION]['message'].format(
            email=email,
            event_name=event_name,
            link=link
        )
    )


This function is called inside the Sessions API, for every speaker of the session as well as for every organizer of the event to which the session is submitted. Inside this function, we use the
send_email().  But firstly we need to create the subject of the email and the message body of the email using the templates and by replacing placeholders by actual value using python formatting. MAILS[NEW_SESSION] returns a unicode string: u’New session proposal for {event_name}’ . So what we do is use the .format() function to replace {event_name} by the actual event_name received as parameter. So it is equivalent to doing something like:

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

which would give us a resulting string of the form:

u'New session proposal for FOSSASIA'

Similarly, we create the html message body using the templates and the parameters received. After this is done, we make a function call to send_email()  which then sends the final email.

References:

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Email and Password Validation in Open Event Android

The Open Event API Server exposes a well documented JSONAPI compliant REST API that can be used in The Open Even Android and Frontend. The Open Event API Server enables the Android and web clients to add the user authentication (sign up/login) in the project. In the process of signing up or logging in user it is needed to validate email and password entered by the user and show the error to give better user experience. In this post I explain how to validate email and password entered by the user using TextInputLayout.

1. Add TextInputLayout

TextInputLayout wraps an EditText (or descendant) to show a floating label when the hint is hidden due to the user inputting text. Add TextInputLayout for email field in the layout as given below.

<android.support.design.widget.TextInputLayout
            android:id="@+id/text_input_layout_email"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <android.support.v7.widget.AppCompatEditText
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:hint="@string/email"
                android:inputType="textEmailAddress" />
</android.support.design.widget.TextInputLayout>

Here the hint attribute is used to display hint in the floating label. Specify the input type so the system displays the appropriate soft input method (such as an on-screen keyboard) for the field. For email EditText we are using textEmailAddress input type. Similarly add TextInputLayout for the password field. The input type for the password is textPassword.

2.  Create and initialize object

Now in the activity create and initialize TextInputLayout and EditText objects for email and password.

@BindView(R.id.text_input_layout_email)
TextInputLayout mTextInputLayoutEmail;
@BindView(R.id.text_input_layout_password)
TextInputLayout mTextInputLayoutPassword;

@Override
protected void onCreate(Bundle savedInstanceState) {
    ButterKnife.bind(this);

    private AppCompatEditText mEditTextEmail = (AppCompatEditText) mTextInputLayoutEmail.getEditText();
    private AppCompatEditText mEditTextPassword = (AppCompatEditText) mTextInputLayoutPassword.getEditText();
}

Here we are using ButterKnife for binding views with fields. The getEditText() method returns the EditText view used for text input inside the TextInputLayout.

3.  Create validate() method

Create validate() method which takes two arguments. The first is email and the second password. It will return true if the email and password are valid else false.

private boolean validate(String email, String password) {

        // Reset errors.
        mTextInputLayoutEmail.setError(null);
        mTextInputLayoutPassword.setError(null);

        if (Utils.isEmpty(email)) {
            mTextInputLayoutEmail.setError("Email is required");
            return false;
        } else if (!Utils.isEmailValid(email)) {
            mTextInputLayoutEmail.setError("Enter a valid email");
            return false;
        }

        if (Utils.isEmpty(password)) {
            mTextInputLayoutPassword.setError("Password is required");
            return false;
        } else if (!Utils.isPasswordValid(password)) {
            mTextInputLayoutPassword.setError("Password must contain at least 6 characters");
            return false;
        }

        return true;
}

Here it first resets the error for the TextInputLayout by setting it to null. Then it checks email string if it is empty then it will show “Email is required” error using setError() method.

4.  Create isEmailValid() and isPasswordValid() method

Now create isEmailValid() and isPasswordvalid() method which is used by validate() method. The isEmailValid() method should take email string as an argument and return boolean indicating whether the email is valid or not. The isEmailValid() method uses Pattern and Matcher class to determine if the pattern of input is email or not. The isPasswordValid() method should take password string as an argument and return true if the password is satisfying minimum condition. Here in our case length of the password should be minimum 6.

public static boolean isEmailValid(String email){
        Pattern pattern = Patterns.EMAIL_ADDRESS;
        Matcher matcher = pattern.matcher(email);
        return matcher.matches();
}

//Check password with minimum requirement here(it should be minimum 6 characters)
public static boolean isPasswordValid(String password){
        return password.length() >= 6;
}

5.  Use validate() method

Now we are ready to use validate() method when signing up or logging in the user. The getText() method of EditText will return text input.

String email = mEditTextEmail.getText().toString();
String password = mEditTextPassword.getText().toString();

if (validate(email, password)) {
    //Sign up or login User
}

Conclusion

Using TextInputLayout with floating hint label and error handling gives awesome UI and UX.

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Mailing Attachments Using Terminal in Open Event Android

The latest version of Open Event Android App Generator, v2 lacked the feature of mailing the generated APK to the email ID that is entered at the start of the app generation process. This also included mailing the error logs in case of APK failure.

This is an important feature for app generator because the process of app generation is a time taking one. The users have to wait for the app to be generated so that they can download the generated APK. To avoid this, the generator can automatically email the APK as soon as it is generated.

I took up this issue a few days back and started working on it. I started with thinking about the ways through which it will be implemented. This required some discussions with the mentors and co-developers. We finalised on the following ways:

  • Using Sendgrid
  • Using SMTP

I will be discussing the implementation of both of them in this blog. The code for APK mailing starts with the function call Notification.send in generator.py

if completed and apk_path and not error:
   Notification.send(
       to=self.creator_email,
       subject='Your android application for %s has been generated ' % self.event_name,
       message='Hi,<br><br>'
               'Your android application for the \'%s\' event has been generated. '
               'And apk file has been attached along with this email.<br><br>'
               'Thanks,<br>'
               'Open Event App Generator' % self.event_name,
       file_attachment=apk_path,
       via_api=self.via_api
   )
else:
   Notification.send(
       to=self.creator_email,
       subject='Your android application for %s could not generated ' % self.event_name,
       message='Hi,<br><br> '
               'Your android application for the \'%s\' event could not generated. '
               'The error message has been provided below.<br><br>'
               '<code>%s</code><br><br>'
               'Thanks,<br>'
               'Open Event App Generator' % (self.event_name, str(error) if error else ''),
       file_attachment=apk_path,
       via_api=self.via_api
   )

This leads me to the class Notification.py. It has three functions:-

1. send(to, subject, message, file_attachment, via_api)
2. send_mail_via_smtp(payload):
3. send_email_via_sendgrid(payload):

As the name suggests, the first function:

send(to, subject, message, file_attachment, via_api)

mainly decides which service (out of smtp and sendgrid) should be used to send the email, on the basis of the input parameters (especially, the ‘EMAIL_SERVICE’ parameter that has to be set in config.py).
The function looks like as follows:

send(to, subject, message, file_attachment, via_api)

It is in the send() that the other two functions are called. If the email_service is smtp, it calls the Notification.send_mail_via_smtp(payload). Otherwise, the Notification.send_email_via_sendgrid(payload) is called.
The sendgrid function is pretty straightforward:

@staticmethod
def send_email_via_sendgrid(payload):

   key = current_app.config['SENDGRID_KEY']
   if not key:
       logger.info('Sendgrid key not defined')
       return
   headers = {
       "Authorization": ("Bearer " + key)
   }
   requests.post(
       "https://api.sendgrid.com/api/mail.send.json",
       data=payload,
       headers=headers
   )

It requires a personalised sendgrid key which is accessed from the config.py file. Apart from that it handles some errors by giving logs in celery tasks. The main line in the function that initiates the email is a POST request made using the python library ‘requests’. The request is made as follows:

 requests.post(
       "https://api.sendgrid.com/api/mail.send.json",
       data=payload,
       headers=headers
   )

The send_mail_via_smtp(payload): function looks for some configurations before sending the mail:

@staticmethod
def send_mail_via_smtp(payload):
   """
   Send email via SMTP
   :param config:
   :param payload:
   :return:
   """
   smtp_encryption = current_app.config['SMTP_ENCRYPTION']
   if smtp_encryption == 'tls':
       smtp_encryption = 'required'
   elif smtp_encryption == 'ssl':
       smtp_encryption = 'ssl'
   elif smtp_encryption == 'tls_optional':
       smtp_encryption = 'optional'
   else:
       smtp_encryption = 'none'
   config = {
       'host': current_app.config['SMTP_HOST'],
       'username': current_app.config['SMTP_USERNAME'],
       'password': current_app.config['SMTP_PASSWORD'],
       'encryption': smtp_encryption,
       'port': current_app.config['SMTP_PORT'],
   }
   mailer_config = {
       'transport': {
           'use': 'smtp',
           'host': config['host'],
           'username': config['username'],
           'password': config['password'],
           'tls': config['encryption'],
           'port': config['port']
       }
   }

   mailer = Mailer(mailer_config)
   mailer.start()
   message = Message(author=payload['from'], to=payload['to'])
   message.subject = payload['subject']
   message.plain = strip_tags(payload['message'])
   message.rich = payload['message']
   message.attach(payload['attachment'])
   mailer.send(message)
   mailer.stop()

It is using the Marrow Mailer Python library to email with attachments(APK). This Python library can be installed using
pip install marrow.mailer
To use Marrow Mailer you instantiate a marrow.mailer.Mailer object with the configuration, then pass Message instances to the Mailer instance’s send() method.

You can refer to the following guides for more information about sending emails through command line:
https://github.com/marrow/mailer is the official repo of Marrow Mailer repository.
https://pypi.python.org/pypi/marrow.mailer
More detailled information on sending emails using Sendgrid can be found here https://www.daveperrett.com/articles/2013/03/19/setting-up-sendmail-with-sendgrid-on-ubuntu/

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How Meilix Generator sends Email Notifications with SendGrid

We wanted to notify the users once the build was ready for download. To solve this we attempted making an email server on Meilix Generator but that can send email when it starts but it would take around 20 minutes to get the build ready so we thought of checking the deploy link status and send email whenever the link status was available (200) but the problem with this method was that the link can be pre available if ISO is rebuilt for same event.

Then, we attempted sending mail by Travis CI but the problem in that was closed SMTP ports (they have a strict policy about that) then we thought that Travis CI can trigger the Sendgrid which can send email to the user with the help of API.

We will use this code so that once the deployment of ISO by Travis CI is done it can execute the email script which requests Sendgrid to send email to the user.

after_deploy:
  - ./mail.py

 

We can create code using code generation service of Sendgrid we are going to choose python as it is easier to manipulate strings in python and we are going to use email as an environment variable.

After generation of python 3 code from the sendgrid website we are going to edit the message and email and hide the API key as an environment variable and create an authorization string to be used there too.

The URL will be generated by the below script as the body of url remains same only two things will change the TRAVIS_TAG which is event name and date.

date = datetime.datetime.now().strftime('%Y%m%d')
url="https://github.com/xeon-zolt/meilix/releases/download/"+os.environ["TRAVIS_TAG"]+"/meilix-zesty-"+date+"-i386.iso"

 

We can use this to hide the api key and use it as an environment variable because if the api key is visible in logs anyone can use it to exploit it and use it for spamming purpose.

authorization = "Bearer " + os.environ["mail_api_key"]
headers = {
    'authorization': authorization,

 

The main thing left to edit in the script is the message which is in the payload and is a string type so we are going to use the email received by Meilix generator as an environment variable and concatenate it with the payload string the message sent is in the value which is in the HTML format and we add the generated URL in similar way we added email variable to string.

payload = "{\"personalizations\":[{\"to\":[{\"email\":\"" + os.environ["email"] + "\"}],\"subject\":\"Your ISO is Ready\"}],\"from\":{\"email\":\"[email protected]\",\"name\":\"Meilix Generator\"},\"reply_to\":{\"email\":\"[email protected]\",\"name\":\"Meilix Generator\"},\"subject\":\"Your ISO is ready\",\"content\":[{\"type\":\"text/html\",\"value\":\"<html><p>Hi,<br>Your ISO is ready<br>URL : "+url+"<br><br>Thank You,<br>Meilix Generator Team</p></html>\"}]}"

 

The sent email looks like this

References

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