Comenzando a utilizar SQLAlchemy

Tuve que reescribir bastante para lograrlo, pero ya funciona :3

files/auth.py

@@ -1,47 +1,46 @@
 import functools
 
-from files.db import get_db
+from files.models import db, User
 
 from werkzeug.exceptions import abort
 from werkzeug.security import check_password_hash
 
 from flask import Blueprint, request, flash, render_template, session, g, redirect, url_for
 
-
 bp = Blueprint('auth', __name__, url_prefix='/auth')
 
+
 @bp.route('/login', methods=('GET', 'POST'))
 def login():
     if request.method == 'POST':
         username = request.form['username']
         password = request.form['password']
 
-        db = get_db()
         error = None
 
-        user = db.execute(
-            'SELECT * FROM users WHERE username = ?', (username,)
-        ).fetchone()
+        user = User.query.filter_by(username=username).first()
 
         if user is None:
             error = 'Incorrect username.'
-        elif not check_password_hash(user['password'], password):
+        elif not check_password_hash(user.password, password):
             error = 'Incorrect password.'
 
         if error is None:
             session.clear()
-            session['user_id'] = user['id']
+            session['user_id'] = user.id
             return redirect(url_for('index'))
 
         flash(error)
 
     return render_template('auth/login.html')
 
+
 @bp.route('/logout')
 def logout():
     session.clear()
     return redirect(url_for('index'))
 
+
 @bp.before_app_request
 def load_logged_in_user():
     user_id = session.get('user_id')
@@ -49,9 +48,7 @@ def load_logged_in_user():
     if user_id is None:
         g.user = None
     else:
-        g.user = get_db().execute(
-            'SELECT * FROM  users WHERE id = ?', (user_id,)
-        ).fetchone()
+        g.user = User.query.get(user_id)
 
 
 def admin_required(view):
@@ -63,4 +60,3 @@ def admin_required(view):
         return view(**kwargs)
 
     return wrapped_view
-