Flask Snippets -- Common architecture patterns when building Flask applications. For learners.

models.py

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

db = SQLAlchemy()


def connect_to_db(app):
    """Helper function to configure the database with the flask app."""
    
    app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql:///blog'
    app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
    db.app = app
    db.init_app(app)
    

def Article(db.Model):
    __tablename__ = 'articles'
    
    title = db.Column(db.String)
    content = db.Column(db.Text)
    
    def __repr__(self):
        return f"<Article {self.id} | {self.title}>"
    
    def save(self):
        """A method to make saving articles simpler."""
        db.session.add(self)
        db.session.commit()


if __name__ == '__main__':
    from server import app
    
    connect_to_db(app)
    db.create_all()
    print('Connected to database.')

server.py

from flask_debugtoolbar import DebugToolbarExtension

from views import app

if __name__ == '__main__':
  app.secret_key = 'secretzzzzzz'
  app.debug = True
  
  DebugToolbarExtension(app)
  app.run()

views.py

from flask import Flask, render_template, redirect

from models import db, Article

app = Flask(__name__)


@app.route('/')
def index():
    """
    This is a view pattern. Note:
    
    * Route decorator on line 5
    * View function (this function)
    """
    # Try to replace your print() statements with logs instead anywhere that you're testing the live server.
    app.logger.info("Home page loaded.")
    return render_template('index.html')

# RESTful routes

@app.route('/articles')
def articles():
    """
    Returns all articles.
    """
    articles = Article.query.all()
    return render_template('articles/list.html', articles=articles)


@app.route('/articles', methods=['POST'])
def article_new():
    """
    Creates a new article and redirects user to it.
    """
    article = Article(title=request.form.get('title'), content=request.form.get('content'))
    db.session.add(article)
    db.session.commit(article)
    
    return redirect(f'/articles/{article.id}')


@app.route('/articles/<int:article_id>')
def article_detail(article_id):
    """
    Returns a specific article.
    
    The route variable `article_id` must be passed to the view function as an argument.
    Their names are arbitrary, but they must match.
    """
    article = Article.query.get(article_id)
    return render_template('articles/detail.html', article=article)


@app.route('/articles/<int:article_id>/edit')
def article_edit(article_id):
    """
    Renders the article's edit page.
    
    The full article content is returned so that the user can view the old and make updates to it.
    """
    article = Article.query.get(article_id)
    return render_template('articles/edit.hmtl', article=article)


@app.route('/articles/<int:article_id>', methods=['POST'])
def article_update(article_id):
    """
    Updates the current article and redirects the user to it.
    """
    article = Article.query.get(article_id)
    new_title = request.form.get('title')
    new_content = request.form.get('content')
    
    if article.title != new_title:
        article.title = new_title
    if article.content != new_content:
        article.content = new_content
   
    db.session.add(article)
    db.session.commit()
    
    return redirect(f'/articles/{article_id}')


@app.route('/articles/<int:article_id>/delete')
def article_delete(article_id):
    article = Article.query.get(article_id)
    db.session.delete(article)
    db.session.commit()
    
    return redirect('/')