I’m struggling to figure out what I’m doing wrong. I’m at step 17 of the FlaskFm project. I’ve changed the my_playlist part of the code as asked but now I’m getting this error when I’m saving my code:
TypeError: str returned non-string (type NoneType)
I think it has something to do with the Song stuff but I’m not sure. Here’s my code:
routes.py
from flask import Flask
from flask_wtf import FlaskForm
from wtforms import StringField, SubmitField
from wtforms.validators import DataRequired
from app import app, db
from models import User, Song, Playlist, Item
from flask import render_template, request, url_for, redirect, flash
#A form for inputing new songs via Dashboard
class SongForm(FlaskForm):
title = StringField(label = "Song Title:", validators=[DataRequired()])
artist = StringField(label = "Artist:", validators=[DataRequired()])
submit = SubmitField("Add Song")
#A function we made to check if an item to be added is already in the playlist
def exists(item, playlist):
"""Return a boolean
True if playlist contains item. False otherwise.
"""
for i in playlist: #for each item in playlist
if i.song_id == item.song_id: #check if the primary key is equal
return True
return False
#The home page of FlaskFM
#Lists all the users currently in the database
#renders the home.html template providing the list of current users
@app.route('/profiles')
def profiles():
current_users = User.query.all() #change here to a database query
return render_template('users.html', current_users = current_users)
#Displays profile pages for a user with the user_id primary key
#renders the profile.html template for a specific user, song library and
#the user's playlist
@app.route('/profile/<int:user_id>')
def profile(user_id):
user = User.query.filter_by(id = user_id).first_or_404(description = "No such user found.")
songs = Song.query.all()
my_playlist = Playlist.query.get(user.playlist_id) #change here to a database query
return render_template('profile.html', user = user, my_playlist = my_playlist, songs = songs)#, my_playlist = my_playlist)
#Adds new songs to a user's playlist from the song library
#redirects back to the profile that issued the addition
@app.route('/add_item/<int:user_id>/<int:song_id>/<int:playlist_id>')
def add_item(user_id, song_id, playlist_id):
new_item = Item(song_id = song_id, playlist_id = playlist_id)
user = User.query.filter_by(id = user_id).first_or_404(description = "No such user found.")
my_playlist = Playlist.query.filter_by(id = user.playlist_id).first()
if not exists(new_item, my_playlist.items):
song = Song.query.get(song_id)
#using db session add the new item
#increase the counter for the song associated with the new item
#commit the database changes here
return redirect(url_for('profile', user_id = user_id))
#Remove an item from a user's playlist
#Redirects back to the profile that issues the removal
@app.route('/remove_item/<int:user_id>/<int:item_id>')
def remove_item(user_id, item_id):
#from the Item model, fetch the item with primary key item_id to be deleted
#using db.session delete the item
#commit the deletion
return redirect(url_for('profile', user_id = user_id))
#Display the Dashboard page with a form for adding songs
#Renders the dashboard template
@app.route('/dashboard', methods=["GET", "POST"])
def dashboard():
form = SongForm()
if request.method == 'POST' and form.validate():
new_song = None
#create a new song here
#add it to the database
#commit to the database
else:
flash(form.errors)
unpopular_songs = [] #add the ordering query here
songs = Song.query.all()
return render_template('dashboard.html', songs = songs, unpopular_songs = unpopular_songs, form = form)
models.py
from app import app, db
#the User model: each user has a username, and a playlist_id foreign key referring
#to the user's Playlist
class User(db.Model):
id = db.Column(db.Integer, primary_key = True)
username = db.Column(db.String(50), index = True, unique = True)
playlist_id = db.Column(db.Integer, db.ForeignKey('playlist.id'))
#representation method
def __repr__(self):
return "{}".format(self.username)
#create the Song model here + add a nice representation method
class Song(db.Model):
id = db.Column(db.Integer, primary_key = True)
artist = db.Column(db.String(50), index = True, unique = False)
title = db.Column(db.String(75), index = True, unique = False)
n = db.Column(db.Integer, index = False, unique = False)
def __repr__(self):
f"{self.title} by {self.artist}"
#create the Item model here + add a nice representation method
class Item(db.Model):
id = db.Column(db.Integer, primary_key = True)
song_id = db.Column(db.Integer, db.ForeignKey('song.id'))
playlist_id = db.Column(db.Integer, db.ForeignKey('playlist.id'))
def __repr__(self):
return "{}".format(self.id)
#create the Playlist model here + add a nice representation method
class Playlist(db.Model):
id = db.Column(db.Integer, primary_key = True)
items = db.relationship('Item', backref = 'playlist', lazy = 'dynamic', cascade = 'all, delete, delete-orphan')
def __repr__(self):
return "{}".format(self.id)
app.py
from flask import Flask, render_template
from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
#set the SQLALCHEMY_DATABASE_URI key
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///song_library.db'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
app.config['SECRET_KEY'] = 'you-will-never-guess'
#create an SQLAlchemy object named `db` and bind it to your app
db = SQLAlchemy(app)
#a simple initial greeting
@app.route('/')
@app.route('/index')
def greeting():
return render_template('greeting.html')
# app name
@app.errorhandler(404)
def not_found(e):
return render_template("404.html")
#uncomment the code below here when you are done creating database instance db and models
import routes
Here’s the full error:
Traceback (most recent call last):
File "/usr/local/lib/python3.6/dist-packages/flask/app.py", line 2463, in __call__
return self.wsgi_app(environ, start_response)
File "/usr/local/lib/python3.6/dist-packages/flask/app.py", line 2449, in wsgi_app
response = self.handle_exception(e)
File "/usr/local/lib/python3.6/dist-packages/flask/app.py", line 1866, in handle_exception
reraise(exc_type, exc_value, tb)
File "/usr/local/lib/python3.6/dist-packages/flask/_compat.py", line 39, in reraise
raise value
File "/usr/local/lib/python3.6/dist-packages/flask/app.py", line 2446, in wsgi_app
response = self.full_dispatch_request()
File "/usr/local/lib/python3.6/dist-packages/flask/app.py", line 1951, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/usr/local/lib/python3.6/dist-packages/flask/app.py", line 1820, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/usr/local/lib/python3.6/dist-packages/flask/_compat.py", line 39, in reraise
raise value
File "/usr/local/lib/python3.6/dist-packages/flask/app.py", line 1949, in full_dispatch_request
rv = self.dispatch_request()
File "/usr/local/lib/python3.6/dist-packages/flask/app.py", line 1935, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/home/ccuser/workspace/project-flask-music/routes.py", line 41, in profile
return render_template('profile.html', user = user, my_playlist = my_playlist, songs = songs)#, my_playlist = my_playlist)
File "/usr/local/lib/python3.6/dist-packages/flask/templating.py", line 140, in render_template
ctx.app,
File "/usr/local/lib/python3.6/dist-packages/flask/templating.py", line 120, in _render
rv = template.render(context)
File "/usr/local/lib/python3.6/dist-packages/jinja2/asyncsupport.py", line 76, in render
return original_render(self, *args, **kwargs)
File "/usr/local/lib/python3.6/dist-packages/jinja2/environment.py", line 1008, in render
return self.environment.handle_exception(exc_info, True)
File "/usr/local/lib/python3.6/dist-packages/jinja2/environment.py", line 780, in handle_exception
reraise(exc_type, exc_value, tb)
File "/usr/local/lib/python3.6/dist-packages/jinja2/_compat.py", line 37, in reraise
raise value.with_traceback(tb)
File "/home/ccuser/workspace/project-flask-music/templates/profile.html", line 3, in top-level template code
{% extends "_base.html" %}
File "/home/ccuser/workspace/project-flask-music/templates/_base.html", line 12, in top-level template code
{% block content %}{% endblock %}
File "/home/ccuser/workspace/project-flask-music/templates/profile.html", line 12, in block "content"
<p>{{song}} {% if my_playlist %}<a href="{{url_for('add_item', user_id = user.id, song_id = song.id, playlist_id = my_playlist.id)}}">Add</a>{% endif %}</p>
TypeError: __str__ returned non-string (type NoneType)
Thanks