Flask blog

This project is my first flask project. It's based on Corey Schafer series of videos on YouTube.

Important notes

Setup

Before running the project, we need to set the environment variable FLASK_APP. the command on windows is set and on linux it's export. So we have to write the following command:
set FLASK_APP=<MAIN_FILE>

DEBUG

To enable the debug mode, we have to write the following command:
set FLASK_DEBUG=1

Running the project

flask run

Form Validation

pip install flask-wtf
pip install email_validator

ORM

pip install flask-sqlalchemy

Creating tables

1. Open shell
2. from <FILE> import db
3. db.create_all()

Creating instances

1. <VARIABLE> = <MODEL>(<FIELDS>)
2. db.session.add(<VARIABLE>)
3. db.session.commit()

Query

• <MODEL>.query.all()
• <MODEL>.query.first()
• <MODEL>.query.filter_by(<FIELD>=<VALUE>).all()
• <MODEL>.query.get(<ID>)

Delete all the tables

db.drop_all()

Password encryption

1. pip install flask-bcrypt
2. from flask_bcrypt import Bcrypt
3. bcrypt = Bcrypt(<APP>)
4. bcrypt.generate_password_hash('<PASSWORD>').decode('utf-8')
   Note that hash is always different. even on the same password. So how to verify?
   bcrypt.check_password_hash(<hashed_password>, <password>)

Login

1. pip install flask-login
2. On __init__.py file, add login_manager = LoginManager(app)
3. On models.py, import login_manager.
4. Now Extension needs to know to find a user by ID. So we create a def load_user(user_id) that gets a user from database by ID. Then we add the @login_manager.user_loader decorator.
5. The extension expects our user model to have certain attributes: is_authenticated, is_active, is_anonymous , get_id(). Therefore, we can import UserMixin from flask_login and finally our user model inherits from that.

Pagination

• posts = Post.query.paginate()
• posts.per_page: Items per page
• posts.page: current page
• for post in posts.items: iterate over page items
• posts = Post.query.paginate(page=2): get the second page's items.
• posts = Post.query.paginate(per_page=5): 5 posts per page.
• posts.total: Total number of posts in all pages.
• for page_number in posts.iter_pages(left_edge=1, right_edge=1, left_current=1, right_current=2): iterate over page numbers

Generate time-sensitive token

1. from itsdangerous import TimedJSONWebSignatureSerializer as Serializer
2. s = Serializer('secret_key_here', expires_in=30) # expires in 30 seconds.
3. token = s.dumps({"user_id": 1}).decode('utf-8')
4. s.loads(token) # works only within 30 seconds.

Send emails

1. pip install flask-mail.
2. On __init__.py file, add app.config['MAIL_SERVER'] = 'smtp.gmail.com' (or your host's smtp server).
3. Add app.config['MAIL_PORT'] = 587.
4. Add app.config['MAIL_USE_TLS'] = True.
5. Add app.config['MAIL_USERNAME'] = os.environ.get('EMAIL_USER').
6. Add app.config['MAIL_PASSWORD'] = os.environ.get('EMAIL_PASS').
7. Add mail = Mail(app).
8. In your code where you want to send an email, create a Message(subject=..., sender=..., recipients=..., body=...,) instance. Then send it using mail.send(message).