2018-02-06T15:11:28Z

The Flask Mega-Tutorial Part X: Email Support

This is the tenth installment of the Flask Mega-Tutorial series, in which I'm going to tell you how your application can send emails to your users, and how to build a password recovery feature on top of the email support.

For your reference, below is a list of the articles in this series.

The application is doing pretty well on the database front now, so in this chapter I want to depart from that topic and add another important piece that most web applications need, which is the sending of emails.

Why does an application need to email its users? There are many reasons, but one common one is to solve authentication related problems. In this chapter I'm going to add a password reset feature for users that forget their password. When a user requests a password reset, the application will send an email with a specially crafted link. The user then needs to click that link to have access to a form in which to set a new password.

The GitHub links for this chapter are: Browse, Zip, Diff.

Introduction to Flask-Mail

As far as the actual sending of emails, Flask has a popular extension called Flask-Mail that can make the task very easy. As always, this extension is installed with pip:

(venv) $ pip install flask-mail

The password reset links will have a secure token in them. To generate these tokens, I'm going to use JSON Web Tokens, which also have a popular Python package:

(venv) $ pip install pyjwt

The Flask-Mail extension is configured from the app.config object. Remember when in Chapter 7 I added the email configuration for sending yourself an email whenever an error occurred in production? I did not tell you this then, but my choice of configuration variables was modeled after Flask-Mail's requirements, so there isn't really any additional work that is needed, the configuration variables are already in the application.

Like most Flask extensions, you need to create an instance right after the Flask application is created. In this case this is an object of class Mail:

app/__init__.py: Flask-Mail instance.

# ...
from flask_mail import Mail

app = Flask(__name__)
# ...
mail = Mail(app)

If you are planning to test sending of emails you have the same options I mentioned in Chapter 7. If you want to use an emulated email server, Python provides one that is very handy that you can start in a second terminal with the following command:

(venv) $ python -m smtpd -n -c DebuggingServer localhost:8025

To configure for this server you will need to set two environment variables:

(venv) $ export MAIL_SERVER=localhost
(venv) $ export MAIL_PORT=8025

If you prefer to have emails sent for real, you need to use a real email server. If you have one, then you just need to set the MAIL_SERVER, MAIL_PORT, MAIL_USE_TLS, MAIL_USERNAME and MAIL_PASSWORD environment variables for it. If you want a quick solution, you can use a Gmail account to send email, with the following settings:

(venv) $ export MAIL_SERVER=smtp.googlemail.com
(venv) $ export MAIL_PORT=587
(venv) $ export MAIL_USE_TLS=1
(venv) $ export MAIL_USERNAME=<your-gmail-username>
(venv) $ export MAIL_PASSWORD=<your-gmail-password>

If you are using Microsoft Windows, you need to replace export with set in each of the export statements above.

Remember that the security features in your Gmail account may prevent the application from sending emails through it unless you explicitly allow "less secure apps" access to your Gmail account. You can read about this here, and if you are concerned about the security of your account, you can create a secondary account that you configure just for testing emails, or you can enable less secure apps only temporarily to run your tests and then revert back to the more secure default.

If you'd like to use a real email server, but don't want to complicate yourself with the Gmail configuration, SendGrid is a good option that gives you 100 emails per day using a free account.

Flask-Mail Usage

To learn how Flask-Mail works, I'll show you how to send an email from a Python shell. So fire up Python with flask shell, and then run the following commands:

>>> from flask_mail import Message
>>> from app import mail
>>> msg = Message('test subject', sender=app.config['ADMINS'][0],
... recipients=['your-email@example.com'])
>>> msg.body = 'text body'
>>> msg.html = '<h1>HTML body</h1>'
>>> mail.send(msg)

The snippet of code above will send an email to a list of email addresses that you put in the recipients argument. I put the sender as the first configured admin (I've added the ADMINS configuration variable in Chapter 7). The email will have plain text and HTML versions, so depending on how your email client is configured you may see one or the other.

So as you see, this is pretty simple. Now let's integrate emails into the application.

A Simple Email Framework

I will begin by writing a helper function that sends an email, which is basically a generic version of the shell exercise from the previous section. I will put this function in a new module called app/email.py:

app/email.py: Email sending wrapper function.

from flask_mail import Message
from app import mail

def send_email(subject, sender, recipients, text_body, html_body):
    msg = Message(subject, sender=sender, recipients=recipients)
    msg.body = text_body
    msg.html = html_body
    mail.send(msg)

Flask-Mail supports some features that I'm not utilizing here such as Cc and Bcc lists. Be sure to check the Flask-Mail Documentation if you are interested in those options.

Requesting a Password Reset

As I mentioned above, I want users to have the option to request their password to be reset. For this purpose I'm going to add a link in the login page:

app/templates/login.html: Password reset link in login form.

    <p>
        Forgot Your Password?
        <a href="{{ url_for('reset_password_request') }}">Click to Reset It</a>
    </p>

When the user clicks the link, a new web form will appear that requests the user's email address as a way to initiate the password reset process. Here is the form class:

app/forms.py: Reset password request form.

class ResetPasswordRequestForm(FlaskForm):
    email = StringField('Email', validators=[DataRequired(), Email()])
    submit = SubmitField('Request Password Reset')

And here is the corresponding HTML template:

app/templates/reset_password_request.html: Reset password request template.

{% extends "base.html" %}

{% block content %}
    <h1>Reset Password</h1>
    <form action="" method="post">
        {{ form.hidden_tag() }}
        <p>
            {{ form.email.label }}<br>
            {{ form.email(size=64) }}<br>
            {% for error in form.email.errors %}
            <span style="color: red;">[{{ error }}]</span>
            {% endfor %}
        </p>
        <p>{{ form.submit() }}</p>
    </form>
{% endblock %}

I also need a view function to handle this form:

app/routes.py: Reset password request view function.

from app.forms import ResetPasswordRequestForm
from app.email import send_password_reset_email

@app.route('/reset_password_request', methods=['GET', 'POST'])
def reset_password_request():
    if current_user.is_authenticated:
        return redirect(url_for('index'))
    form = ResetPasswordRequestForm()
    if form.validate_on_submit():
        user = User.query.filter_by(email=form.email.data).first()
        if user:
            send_password_reset_email(user)
        flash('Check your email for the instructions to reset your password')
        return redirect(url_for('login'))
    return render_template('reset_password_request.html',
                           title='Reset Password', form=form)

This view function is fairly similar to others that process a form. I start by making sure the user is not logged in. If the user is logged in, then there is no point in using the password reset functionality, so I redirect to the index page.

When the form is submitted and valid, I look up the user by the email provided by the user in the form. If I find the user, I send a password reset email. The send_password_reset_email() helper function performs this task. I will show you this function below.

After the email is sent, I flash a message directing the user to look for the email for further instructions, and then redirect back to the login page. You may notice that the flashed message is displayed even if the email provided by the user is unknown. This is so that clients cannot use this form to figure out if a given user is a member or not.

Password Reset Tokens

Before I implement the send_password_reset_email() function, I need to have a way to generate a password request link. This is going to be the link that is sent to the user via email. When the link is clicked, a page where a new password can be set is presented to the user. The tricky part of this plan is to make sure that only valid reset links can be used to reset an account's password.

The links are going to be provisioned with a token, and this token will be validated before allowing the password change, as proof that the user that requested the email has access to the email address on the account. A very popular token standard for this type of process is the JSON Web Token, or JWT. The nice thing about JWTs is that they are self contained. You can send a token to a user in an email, and when the user clicks the link that feeds the token back into the application, it can be verified on its own.

How do JWTs work? Nothing better than a quick Python shell session to understand them:

>>> import jwt
>>> token = jwt.encode({'a': 'b'}, 'my-secret', algorithm='HS256')
>>> token
'eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJhIjoiYiJ9.dvOo58OBDHiuSHD4uW88nfJik_sfUHq1mDi4G0'
>>> jwt.decode(token, 'my-secret', algorithms=['HS256'])
{'a': 'b'}

The {'a': 'b'} dictionary is an example payload that is going to be written into the token. To make the token secure, a secret key needs to be provided to be used in creating a cryptographic signature. For this example I have used the string 'my-secret', but with the application I'm going to use the SECRET_KEY from the configuration. The algorithm argument specifies how the token is to be generated. The HS256 algorithm is the most widely used.

As you can see the resulting token is a long sequence of characters. But do not think that this is an encrypted token. The contents of the token, including the payload, can be decoded easily by anyone (don't believe me? Copy the above token and then enter it in the JWT debugger to see its contents). What makes the token secure is that the payload is signed. If somebody tried to forge or tamper with the payload in a token, then the signature would be invalidated, and to generate a new signature the secret key is needed. When a token is verified, the contents of the payload are decoded and returned back to the caller. If the token's signature was validated, then the payload can be trusted as authentic.

The payload that I'm going to use for the password reset tokens is going to have the format {'reset_password': user_id, 'exp': token_expiration}. The exp field is standard for JWTs and if present it indicates an expiration time for the token. If a token has a valid signature, but it is past its expiration timestamp, then it will also be considered invalid. For the password reset feature, I'm going to give these tokens 10 minutes of life.

When the user clicks on the emailed link, the token is going to be sent back to the application as part of the URL, and the first thing the view function that handles this URL will do is to verify it. If the signature is valid, then the user can be identified by the ID stored in the payload. Once the user's identity is known, the application can ask for a new password and set it on the user's account.

Since these tokens belong to users, I'm going to write the token generation and verification functions as methods in the User model:

app/models.py: Reset password token methods.

from time import time
import jwt
from app import app

class User(UserMixin, db.Model):
    # ...

    def get_reset_password_token(self, expires_in=600):
        return jwt.encode(
            {'reset_password': self.id, 'exp': time() + expires_in},
            app.config['SECRET_KEY'], algorithm='HS256')

    @staticmethod
    def verify_reset_password_token(token):
        try:
            id = jwt.decode(token, app.config['SECRET_KEY'],
                            algorithms=['HS256'])['reset_password']
        except:
            return
        return User.query.get(id)

The get_reset_password_token() function returns a JWT token as a string, which is generated directly by the jwt.encode() function.

The verify_reset_password_token() is a static method, which means that it can be invoked directly from the class. A static method is similar to a class method, with the only difference that static methods do not receive the class as a first argument. This method takes a token and attempts to decode it by invoking PyJWT's jwt.decode() function. If the token cannot be validated or is expired, an exception will be raised, and in that case I catch it to prevent the error, and then return None to the caller. If the token is valid, then the value of the reset_password key from the token's payload is the ID of the user, so I can load the user and return it.

Sending a Password Reset Email

The send_password_reset_email() function relies on the send_email() function I wrote above to generate the password reset emails.

app/email.py: Send password reset email function.

from flask import render_template
from app import app

# ...

def send_password_reset_email(user):
    token = user.get_reset_password_token()
    send_email('[Microblog] Reset Your Password',
               sender=app.config['ADMINS'][0],
               recipients=[user.email],
               text_body=render_template('email/reset_password.txt',
                                         user=user, token=token),
               html_body=render_template('email/reset_password.html',
                                         user=user, token=token))

The interesting part in this function is that the text and HTML content for the emails is generated from templates using the familiar render_template() function. The templates receive the user and the token as arguments, so that a personalized email message can be generated. Here is the text template for the reset password email:

app/templates/email/reset_password.txt: Text for password reset email.

Dear {{ user.username }},

To reset your password click on the following link:

{{ url_for('reset_password', token=token, _external=True) }}

If you have not requested a password reset simply ignore this message.

Sincerely,

The Microblog Team

And here is the nicer HTML version of the same email:

app/templates/email/reset_password.html: HTML for password reset email.

<p>Dear {{ user.username }},</p>
<p>
    To reset your password
    <a href="{{ url_for('reset_password', token=token, _external=True) }}">
        click here
    </a>.
</p>
<p>Alternatively, you can paste the following link in your browser's address bar:</p>
t<p>{{ url_for('reset_password', token=token, _external=True) }}</p>
<p>If you have not requested a password reset simply ignore this message.</p>
<p>Sincerely,</p>
<p>The Microblog Team</p>

The reset_password route that is referenced in the url_for() call in these two email templates does not exist yet, this will be added in the next section. The _external=True argument that I included in the url_for() calls in both templates is also new. The URLs that are generated by url_for() by default are relative URLs that only include the path portion of the URL. This is normally sufficient for links that are generated in web pages, because the web browser completes the URL by taking the missing parts from the URL in the address bar. When sending a URL by email however, that context does not exist, so fully qualified URLs need to be used. When _external=True is passed as an argument, complete URLs are generated, so the previous example would return http://localhost:5000/user/susan, or the appropriate URL when the application is deployed on a domain name.

Resetting a User Password

When the user clicks on the email link, a second route associated with this feature is triggered. Here is the password request view function:

app/routes.py: Password reset view function.

from app.forms import ResetPasswordForm

@app.route('/reset_password/<token>', methods=['GET', 'POST'])
def reset_password(token):
    if current_user.is_authenticated:
        return redirect(url_for('index'))
    user = User.verify_reset_password_token(token)
    if not user:
        return redirect(url_for('index'))
    form = ResetPasswordForm()
    if form.validate_on_submit():
        user.set_password(form.password.data)
        db.session.commit()
        flash('Your password has been reset.')
        return redirect(url_for('login'))
    return render_template('reset_password.html', form=form)

In this view function I first make sure the user is not logged in, and then I determine who the user is by invoking the token verification method in the User class. This method returns the user if the token is valid, or None if not. If the token is invalid I redirect to the home page.

If the token is valid, then I present the user with a second form, in which the new password is requested. This form is processed in a way similar to previous forms, and as a result of a valid form submission, I invoke the set_password() method of User to change the password, and then redirect to the login page, where the user can now login.

Here is the ResetPasswordForm class:

app/forms.py: Password reset form.

class ResetPasswordForm(FlaskForm):
    password = PasswordField('Password', validators=[DataRequired()])
    password2 = PasswordField(
        'Repeat Password', validators=[DataRequired(), EqualTo('password')])
    submit = SubmitField('Request Password Reset')

And here is the corresponding HTML template:

app/templates/reset_password.html: Password reset form template.

{% extends "base.html" %}

{% block content %}
    <h1>Reset Your Password</h1>
    <form action="" method="post">
        {{ form.hidden_tag() }}
        <p>
            {{ form.password.label }}<br>
            {{ form.password(size=32) }}<br>
            {% for error in form.password.errors %}
            <span style="color: red;">[{{ error }}]</span>
            {% endfor %}
        </p>
        <p>
            {{ form.password2.label }}<br>
            {{ form.password2(size=32) }}<br>
            {% for error in form.password2.errors %}
            <span style="color: red;">[{{ error }}]</span>
            {% endfor %}
        </p>
        <p>{{ form.submit() }}</p>
    </form>
{% endblock %}

The password reset feature is now complete, so make sure you try it.

Asynchronous Emails

If you are using the simulated email server that Python provides you may not have noticed this, but sending an email slows the application down considerably. All the interactions that need to happen when sending an email make the task slow, it usually takes a few seconds to get an email out, and maybe more if the email server of the addressee is slow, or if there are multiple addressees.

What I really want is for the send_email() function to be asynchronous. What does that mean? It means that when this function is called, the task of sending the email is scheduled to happen in the background, freeing the send_email() to return immediately so that the application can continue running concurrently with the email being sent.

Python has support for running asynchronous tasks, actually in more than one way. The threading and multiprocessing modules can both do this. Starting a background thread for email being sent is much less resource intensive than starting a brand new process, so I'm going to go with that approach:

app/email.py: Send emails asynchronously.

from threading import Thread
# ...

def send_async_email(app, msg):
    with app.app_context():
        mail.send(msg)


def send_email(subject, sender, recipients, text_body, html_body):
    msg = Message(subject, sender=sender, recipients=recipients)
    msg.body = text_body
    msg.html = html_body
    Thread(target=send_async_email, args=(app, msg)).start()

The send_async_email function now runs in a background thread, invoked via the Thread class in the last line of send_email(). With this change, the sending of the email will run in the thread, and when the process completes the thread will end and clean itself up. If you have configured a real email server, you will definitely notice a speed improvement when you press the submit button on the password reset request form.

You probably expected that only the msg argument would be sent to the thread, but as you can see in the code, I'm also sending the application instance. When working with threads there is an important design aspect of Flask that needs to be kept in mind. Flask uses contexts to avoid having to pass arguments across functions. I'm not going to go into a lot of detail on this, but know that there are two types of contexts, the application context and the request context. In most cases, these contexts are automatically managed by the framework, but when the application starts custom threads, contexts for those threads may need to be manually created.

There are many extensions that require an application context to be in place to work, because that allows them to find the Flask application instance without it being passed as an argument. The reason many extensions need to know the application instance is because they have their configuration stored in the app.config object. This is exactly the situation with Flask-Mail. The mail.send() method needs to access the configuration values for the email server, and that can only be done by knowing what the application is. The application context that is created with the with app.app_context() call makes the application instance accessible via the current_app variable from Flask.

304 comments

  • #276 Miguel Grinberg said 2021-03-04T14:25:24Z

    @tim: this depends on how you initialize the Flask-Mail extension. In general you cannot rely on the extension knowing what the app instance is, but when you initialize directly with app then it does have access to it.

  • #277 Haley said 2021-03-06T18:27:16Z

    Hi Miguel, Thank you so much for this great tutorial, it's been so helpful to me and I really appreciate how descriptive you are, it's super easy to follow. I had one issue on this part since I re-structured the application using blueprints, and was curious if you had any insight or ideas. After I restructured the application - when a user requests the password reset link (it still works fine), but the CSS does not load for the reset password link. The css works for all other pages though, so I'm not sure what's causing that. I was wondering if it's got something to do with the _external=True, but couldn't find anything through google. Appreciate any insight or ideas if you have them! Thanks again for this awesome tutorial.

    Haley

  • #278 Miguel Grinberg said 2021-03-06T20:02:48Z

    @Haley: you need to look in the browser's network tab to see if the CSS if being loaded or not. Also see if there are any errors in the terminal that is running Flask.

  • #279 Francisco said 2021-03-27T02:12:40Z

    Hello Miguel, Following the DRY - don't repeat yourself principle, in this case avoiding the overhead of additional libraries, it would be appreciated to know what are the true benefits of using Flask-Mail vs smtplib+email vs logging. For the smtplib+email built-in Python packages, the example the user @Laurence in this thread gave works. For an even more simple example, using logging.SMTPHandler, from logging built-inlibrary: import logging

    <h1>THIS WORKS!</h1> <h1>set formatter</h1>

    logformatter = logging.Formatter( fmt='%(asctime)s.%(msecs)03d - %(name)s - %(levelname)s - %(message)s', datefmt='%d/%m/%Y %H:%M:%S' )

    <h1>set handler</h1>

    logsmtphandler_gmail = logging.handlers.SMTPHandler( mailhost = ("smtp.googlemail.com",587), # does not matter this because the real email in credentials is shown fromaddr = "local@localhost", # works to send and receive emails in SMTP localhost Server toaddrs = ["<any_real_email>"], subject = "alert!", credentials=("<gmail_email>", "<gmail_password"), #None, secure=(), #None, timeout=1.0 )

    <h1>set level</h1>

    logsmtphandler_gmail.setLevel(logging.INFO) logsmtphandler_gmail.setFormatter(logformatter)

    <h1>set logger</h1>

    loglogger_resetspass = logging.getLogger('myapp.user_example.resetspass') loglogger_resetspass.addHandler(logsmtphandler_gmail) loglogger_resetspass.critical("<reset password email>")

    So far, the difference apparently is: -> other solutions are lower level than Flask-Mail (which are ok, if needed to adapt) -> logging.SMTPHandler seems to only send well to real emails, by using a real gmail or other well known account, it could be a matter of configuration though. - > logging is traditionally used to be used to communicate internally within the team, although nothing stops from using it outside of that semantic, specially if used well the loggers hierarchies, which can serve for example to organize emails sent to user by: logger_name.user_name.email_type

    The only benefit i see with Flask-Mail is that it sends real emails without requiring real known accounts easier (less configuration) than for example logging.SMTPHandler.

  • #280 Miguel Grinberg said 2021-03-27T23:30:08Z

    @Francisco: Flask-Mail is a wrapper for the libraries that you mention, so email sending is exactly the same. The only convenience is that the configuration is integrated with the Flask config object.

  • #281 Maulik said 2021-03-30T11:28:52Z

    Hello Miguel, Thanks for this great tutorial..

    It is cumbersome to set MAIL_SERVER, MAIL_PORT...etc each time I start terminal. Do save time, I added these variables in .flaskenv file but application is not taking these variables values. Can you please tell me how to permanently set the values of Environment variables?

  • #282 Miguel Grinberg said 2021-03-30T13:25:23Z

    @Maulik: The variables should work in the .flaskenv file, as long as you start the server with "flask run". Later in the tutorial I show how to use a .env file, separate from .flaskenv for storing secrets and credentials. This is in the chapter about Linux deployment, if you want to take a peek.

  • #283 bob said 2021-04-22T13:06:28Z

    Hi, i just get this error KeyError: 'ADMINS' in the email.py file thanks

  • #284 Miguel Grinberg said 2021-04-23T10:14:12Z

    @bob: you have not defined the ADMINS configuration variable as indicated in Part 7 of this tutorial.

  • #285 Jonathan said 2021-04-26T23:00:51Z

    Hello Miguel,

    Great work. I like your style. I bought your Flask MegaTutorial and IoT Micropython Courses; and am looking forward to the latter.

    I implemented the above email setup using a new email address with 2-facter authentication and app password setup via gmail (recommended by stack overflow). The system is working 100% correctly.

    My issue is that all of the password reset emails are going to spam. I am sending via my new email address for this tutorial; but receiving on my private email. The emails were received and the links + forms all work correctly.

    Do you have a suggestion how to format the email to be less likely to hit gmail (or other servers') spam detectors? SO suggested to make the test more TEXT than HTML. Specifically, they say to reduce the HTML to TEXT ratio below half.

    Thank you!

  • #286 Miguel Grinberg said 2021-04-27T22:03:17Z

    @Jonathan: Is your sender email server up to date with SPF and DKIM configuration?

  • #287 Abhishek said 2021-06-23T10:50:35Z

    Hi Miguel, I'm getting the following error, unable to trace the mistake. Can you please look into this? Error: While importing 'microblog', an ImportError was raised:

    Traceback (most recent call last): File "/home/dell/Documents/microblog/venv/lib/python3.8/site-packages/flask/cli.py", line 256, in locate_app import(module_name) File "/home/dell/Documents/microblog/microblog.py", line 1, in <module> from app import app, db File "/home/dell/Documents/microblog/app/init.py", line 48, in <module> from app import routes, models, errors File "/home/dell/Documents/microblog/app/routes.py", line 18, in <module> from app.email import send_password_reset_email ImportError: cannot import name 'send_password_reset_email' from 'app.email' (/home/dell/Documents/microblog/app/email.py)

  • #288 Miguel Grinberg said 2021-06-23T11:51:27Z

    @Abhishek: the error explains the problem. You don't have a send_password_reset_email in the app/email.py file.

  • #289 Abhishek said 2021-06-23T13:15:05Z

    Yes, I got it. Thanks for the reply. Isn't the email.py should be like this?

    from flask_mail import Message

    class send_password_reset_email: def send_email(subject, sender, recipients, text_body, html_body): from app import mail msg = Message(subject, sender=sender, recipients=recipients) msg.body = text_body msg.html = html_body mail.send(msg)

    I think class send_password_reset_email: is missing in the code(this tutorial), or am I missing something?

  • #290 Miguel Grinberg said 2021-06-23T17:06:31Z

    @Abhishek: Are you using the code from this article? send_password_reset_email is a function, not a class. There is a download link in the introduction section if you need to see my code and compare it against yours.

  • #291 Newton said 2021-07-11T19:36:53Z

    I really want to appreciate you for this tutorial, it’s amazing, how much i have learn’t in such a short time, may posterity reward you immensely

  • #292 Hamid Allaoui said 2021-10-25T20:28:25Z

    Thank you so much for this great tutorial.

  • #293 Nkiru said 2021-11-26T16:08:47Z

    Thank you so much Miguel for this wonderful tutorials. I have learnt a lot from it so far.

    I have one an issue each time I want to use "Reset password"

    I see this message on my terminal:

    line 361, in send raise SMTPServerDisconnected('please run connect() first') smtplib.SMTPServerDisconnected: please run connect() first

    I also do not receive any mail on the email I provided. I have tried many options to fix it yet nothing.

    Please sir, is there something you can do to help me out.

    Thank you so much

  • #294 Miguel Grinberg said 2021-11-26T16:36:51Z

    @Nkiru: your email configuration is incorrect.

  • #295 Firas Farah said 2022-02-09T18:21:54Z

    Hi Miguel,

    One of the best tutorials that I have ever had the pleasure of working with! Hats off to you!

    One simple observation on this chapter: you have two different files named "reset_password.html"

    • One for the actual email message for the user to reset their email (template/email/reset_password.html)
    • One for the actual template: (app/templates/reset_password.html)

    This is bound to ultimately create confusion for the app!

  • #296 Miguel Grinberg said 2022-02-10T00:03:55Z

    @Firas: one is the reset password page, the other is the reset password email. The email is under a separate folder, so there is no collision. If you prefer different names, you are welcome to rename one of them.

  • #297 Arnolf said 2022-02-12T08:25:44Z

    Hi! Miguel Grinberg how to thread flask background task with decorator i have this error RuntimeError: Working outside of application context. import threading

    from flask import current_app

    def threaded(func): def wrapper(args, *kwargs): with current_app.app_context(): thread = threading.Thread(target=func, args=args, kwargs=kwargs) thread.start() return thread

    return wrapper
    

    I would like to do it this way to use it more often. without having to use Thread directly in the a function body

  • #298 Miguel Grinberg said 2022-02-12T10:40:22Z

    @Arnolf: you can't use current_app. Import your app object and use it directly. Then pass the app object to the thread, and create an app context directly in the thread.

  • #299 Lukas said 2022-04-22T13:00:52Z

    Great tutorial!

    Do you have any idea how to change the credentials for the mail server during runtime? I want to make the SMTP settings configurable via the client.

    Thanks, Lukas

  • #300 Miguel Grinberg said 2022-04-22T13:43:17Z

    @Lukas: Don't use Flask-Mail for that. Instead use the SMTP support in the Python standard library, and store your per-user email credentials in your database.

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