model.py

"""Models and database functions for Ratings project."""

from flask_sqlalchemy import SQLAlchemy
from datetime import datetime
from correlation import pearson

# This is the connection to the PostgreSQL database; we're getting this through
# the Flask-SQLAlchemy helper library. On this, we can find the `session`
# object, where we do most of our interactions (like committing, etc.)

db = SQLAlchemy()


##############################################################################
# Model definitions

class User(db.Model):
    """User of ratings website."""

    __tablename__ = "users"

    user_id = db.Column(db.Integer, autoincrement=True, primary_key=True)
    email = db.Column(db.String(64), nullable=True)
    password = db.Column(db.String(64), nullable=True)
    age = db.Column(db.Integer, nullable=True)
    zipcode = db.Column(db.String(15), nullable=True)

    def __repr__(self):
        """Provide helpful representation when printed."""

        return "<User user_id=%s email=%s>" % (self.user_id, self.email)

    def similarity(self, other):

        u_ratings = {}
        paired_ratings = []
        for r in self.ratings:
            u_ratings[r.movie_id] = r

        for r in other.ratings:
            u_rating = u_ratings.get(r.movie_id)
            if u_rating is not None:
                pair = (u_rating.score, r.score)
                paired_ratings.append(pair)

        result = 0.0
        if paired_ratings:
            result = pearson(paired_ratings)

        return result

    def calculate_movie_similarities(self, movie_id):
        similarity_ranks = []
        m = Movie.query.filter_by(movie_id=movie_id).one()

        other_users = [r.user for r in m.ratings]

        for other_u in other_users:
            similarity_ranks.append((self.similarity(other_u), other_u))
        similarity_ranks.sort()
        print similarity_ranks


# Put your Movie and Rating model classes here.

class Movie(db.Model):
    """Movies on this site."""

    __tablename__ = "movies"

    movie_id = db.Column(db.Integer, autoincrement=True, primary_key=True)
    title = db.Column(db.String(100))
    released_at = db.Column(db.DateTime)
    imdb_url = db.Column(db.String(150))


class Rating(db.Model):
    """User ratings of movies."""

    __tablename__ = "ratings"

    rating_id = db.Column(db.Integer, autoincrement=True, primary_key=True)
    movie_id = db.Column(db.Integer, db.ForeignKey("movies.movie_id"))
    user_id = db.Column(db.Integer, db.ForeignKey("users.user_id"))
    score = db.Column(db.Integer)

    #Define the relationship to user
    user = db.relationship("User",
                           backref=db.backref("ratings", order_by=rating_id))

    #Define the relationship to movie
    movie = db.relationship("Movie",
                            backref=db.backref("ratings", order_by=rating_id))

##############################################################################
# Helper functions

def connect_to_db(app):
    """Connect the database to our Flask app."""

    # Configure to use our PstgreSQL database
    app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql:///ratings'
    db.app = app
    db.init_app(app)


if __name__ == "__main__":
    # As a convenience, if we run this module interactively, it will leave
    # you in a state of being able to work with the database directly.

    from server import app
    connect_to_db(app)
    print "Connected to DB."