main_app.py

#__author__ == "Jackie Cohen (jczetta)"

import os
from flask import Flask, render_template, session, redirect, url_for # tools that will make it easier to build on things
from flask_sqlalchemy import SQLAlchemy # handles database stuff for us - need to pip install flask_sqlalchemy in your virtual env, environment, etc to use this and run this

# Application configurations
app = Flask(__name__)
app.debug = True
app.use_reloader = True
app.config['SECRET_KEY'] = 'hard to guess string for app security adgsdfsadfdflsdfsj'

app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///./sample_songs.db' # TODO: decide what your new database name will be -- that has to go here
app.config['SQLALCHEMY_COMMIT_ON_TEARDOWN'] = True
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False


# Set up Flask debug stuff
db = SQLAlchemy(app) # For database use
session = db.session # to make queries easy





#########
######### Everything above this line is important/useful setup, not problem-solving.
#########


##### Set up Models #####

# Set up association Table between artists and albums
collections = db.Table('collections',db.Column('album_id',db.Integer, db.ForeignKey('albums.id')),db.Column('artist_id',db.Integer, db.ForeignKey('artists.id')))

class Album(db.Model):
    __tablename__ = "albums"
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(64))
    artists = db.relationship('Artist',secondary=collections,backref=db.backref('albums',lazy='dynamic'),lazy='dynamic')
    songs = db.relationship('Song',backref='Album')


class Artist(db.Model):
    __tablename__ = "artists"
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(64))
    songs = db.relationship('Song',backref='Artist')

    def __repr__(self):
        return "{} (ID: {})".format(self.name,self.id)


class Song(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String(64),unique=True) # Only unique title songs can exist in this data model
    album_id = db.Column(db.Integer, db.ForeignKey("albums.id")) #ok to be null for now
    artist_id = db.Column(db.Integer, db.ForeignKey("artists.id")) # ok to be null for now
    genre = db.Column(db.String(64)) # ok to be null
    # keeping genre as atomic element here even though in a more complex database it could be its own table and be referenced here

    def __repr__(self):
        return "{} by {} | {}".format(self.title,self.artist_id, self.genre)


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

### For database additions
### Relying on global session variable above existing

def get_or_create_artist(artist_name):
    artist = Artist.query.filter_by(name=artist_name).first()
    if artist:
        return artist
    else:
        artist = Artist(name=artist_name)
        session.add(artist)
        session.commit()
        return artist


##### Set up Controllers (route functions) #####

## Main route
@app.route('/')
def index():
    songs = Song.query.all()
    num_songs = len(songs)
    return render_template('index.html', num_songs=num_songs)

@app.route('/song/new/<title>/<artist>/<genre>/')
def new_song(title, artist, genre):
    if Song.query.filter_by(title=title).first(): # if there is a song by that title
        return "That song already exists! Go back to the main app!"
    else:
        artist = get_or_create_artist(artist)
        song = Song(title=title, artist_id=artist.id,genre=genre)
        session.add(song)
        session.commit()
        return "New song: {} by {}. Check out the URL for ALL songs to see the whole list.".format(song.title, artist.name)

@app.route('/all_songs')
def see_all():
    all_songs = [] # Will be be tuple list of title, genre
    songs = Song.query.all()
    for s in songs:
        artist = Artist.query.filter_by(id=s.artist_id).first() # get just one artist instance
        all_songs.append((s.title,artist.name, s.genre)) # get list of songs with info to easily access [not the only way to do this]
    return render_template('all_songs.html',all_songs=all_songs) # check out template to see what it's doing with what we're sending!

@app.route('/all_artists')
def see_all_artists():
    artists = Artist.query.all()
    names = []
    for a in artists:
        num_songs = len(Song.query.filter_by(artist_id=a.id).all())
        newtup = (a.name,num_songs)
        names.append(newtup) # names will be a list of tuples
    return render_template('all_artists.html',artist_names=names)


if __name__ == '__main__':
    db.create_all() # This will create database in current directory, as set up, if it doesn't exist, but won't overwrite if you restart - so no worries about that
    app.run() # run with this: python main_app.py runserver