gistfile1.py

# In views.py

import flask
from flask import request, session, g
from datably import app, crypt, db
from datably import operations as ops

@app.route('/login', methods=('GET', 'POST'))
def login():
    context = {}

    if request.method == 'POST':
        app.logger.debug(request.form['email'])
        user, errmsg = ops.login_user()
        if user:
            return flask.redirect(flask.url_for('index'))
        else:
            context.update({
                'errmsg': errmsg,
            })

    return flask.render_template('login.html', **context)

# In operations.py

import sqlalchemy
import flask
from flask import request, session, g
from datably import app, crypt, db
from datably.models import User

def login_user():
    """
    Logs a user in and updates the session accordingly.

    Returns a tuple consisting of the user (or ``None`` 
    if there is an error) and an error message (or 
    ``None`` on success).
    """
    email = request.form['email'],
    app.logger.debug(email)
    password = request.form['password']
 
    user = User.query.filter_by(email=email).first()

    if not user:
        return (None, 'User not found.')

    if user.password_matches(password):
        session['user'] = user
        return (user, None)
    else:
        return (None, 'Incorrect password.')