models.py

#IMPORTS
from flask_sqlalchemy import SQLAlchemy
from datetime import datetime
db = SQLAlchemy()
#----------------------------------------------------------------------------#
# Models.
#----------------------------------------------------------------------------#

#Intialization of a Many to Many relationship Model(Genre) to Artist and Venue
class Genre(db.Model):
    __tablename__ = 'Genre'
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String)

# Association tables for Artist to Genre (many2many) and Venue to Genre (many2many)
artist_genre_table = db.Table('artist_genre_table',
    db.Column('genre_id', db.Integer, db.ForeignKey('Genre.id'), primary_key=True),
    db.Column('artist_id', db.Integer, db.ForeignKey('Artist.id'), primary_key=True)
)

venue_genre_table = db.Table('venue_genre_table',
    db.Column('genre_id', db.Integer, db.ForeignKey('Genre.id'), primary_key=True),
    db.Column('venue_id', db.Integer, db.ForeignKey('Venue.id'), primary_key=True)
)


class Venue(db.Model):
    __tablename__ = 'Venue'
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String)
    city = db.Column(db.String(120))
    state = db.Column(db.String(120))
    address = db.Column(db.String(120))
    phone = db.Column(db.String(120))
    image_link = db.Column(db.String(500))
    facebook_link = db.Column(db.String(120))
    # Here we link the associative table for the m2m relationship with genre
    genres = db.relationship('Genre', secondary=venue_genre_table, backref=db.backref('venues'))
    website = db.Column(db.String(120))
    seeking_talent = db.Column(db.Boolean, default=False)
    seeking_description = db.Column(db.String(120))
    # Venue is the parent (one-to-many) of a Show (Artist is also a foreign key, in def. of Show)
     # Can reference show.venue (as well as venue.shows)
    shows = db.relationship('Show', backref='venue', lazy='joined', cascade="all, delete")  

    def __repr__(self):
        return f'<Venue {self.id} {self.name}>'


class Artist(db.Model):
    __tablename__ = 'Artist'
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String)
    city = db.Column(db.String(120))
    state = db.Column(db.String(120))
    phone = db.Column(db.String(120))
    image_link = db.Column(db.String(500))
    facebook_link = db.Column(db.String(120))
    # Here we link the associative table for the many 2 many relationship with genre
    genres = db.relationship('Genre', secondary=artist_genre_table, backref=db.backref('artists'))
    website = db.Column(db.String(120))
    seeking_venue = db.Column(db.Boolean, default=False)
    seeking_description = db.Column(db.String(120))
    # Artist is the parent (one-to-many) of a Show (Venue is also a foreign key, in def. of Show)
    # Can reference show.artist (as well as artist.shows) 
    shows = db.relationship('Show', backref='artist', lazy='joined', cascade="all, delete")  

    def __repr__(self):
        return f'<Artist {self.id} {self.name}>'


class Show(db.Model):
    __tablename__ = 'Show'
    id = db.Column(db.Integer, primary_key=True)
    start_time = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)   
    artist_id = db.Column(db.Integer, db.ForeignKey('Artist.id'), nullable=False)   
    venue_id = db.Column(db.Integer, db.ForeignKey('Venue.id'), nullable=False)

    def __repr__(self):
        return f'<Show {self.id} {self.start_time} artist_id={self.artist_id} venue_id={self.venue_id}>'