Making a reading list and confused about ManyToMany relationship between the models - Django

Question

I am making an app where a user can save books to a "reading" list. I have created 2 models to connect to the custom User model(AbstractBaseUser) I have made.

I am learning how to do this and have been reading the docs.

For the book Model this is what I have. I have created a ManyToMany key with the user since I want the books to be able to be added by other users to their lists once it has been inputted into the book database.

Books model.py

class Books(models.Model):
ONESTAR = "BD"
TWOSTAR = "OK"
THREESTAR = "GD"
FOURSTAR = "VG"
FIVESTAR = "EX"
DEFAULT = "NA"
READ  = "RB"
NOT_READ = "NR"
WANT_READ = "WR"

BOOK_REVIEW_CHOICES = (
    (DEFAULT, 'Rate Book'),
    (FIVESTAR, 'Excellent'),
    (FOURSTAR, 'Very Good'),
    (THREESTAR, 'Good'),
    (TWOSTAR,'Okay'),
    (ONESTAR, 'Bad'),
)

READ_BOOKS_CHOICES = (
    (READ,  'Read Book'),
    (NOT_READ, 'Didnt Read Book'),
    (WANT_READ, 'Want To Read')
    )

user = models.ManyToManyField(UsrAccounts, related_name='users')
title = models.CharField(max_length=300)
author = models.CharField(max_length=255)
description = models.CharField(max_length=500)
book_rating = models.CharField(max_length=2,choices=BOOK_REVIEW_CHOICES, default = DEFAULT)
read_status = models.CharField(max_length=2, choices=READ_BOOKS_CHOICES, default = READ)
image = models.ImageField(upload_to = user_directory_path, null= True, blank=True)
date_added = models.DateTimeField(auto_now=False, auto_now_add=True)
last_updated = models.DateTimeField(auto_now=True, auto_now_add=False)

For the list model I have a foreign key for a ManyToOne relationship between a list and user but a ManyToMany between a list and books.

my List Model.py

class MyList(models.Model):
user = models.ForeignKey(
    'accounts.UsrAccounts',
    on_delete=models.CASCADE)
title = models.CharField(max_length=500)
books = models.ManyToManyField(Books, related_name='books')

Did I set this up right?

Shang Wang · Accepted Answer · 2016-01-25T19:11:23.733

2

If I understand you correctly, you should setup M2M field on UserAccount model point to Book model:

class UserAccount(models.Model):
    reading_list = models.ManyToManyField('Book', blank=True)

If you want to give reading list a title, you should use another model to hold that, like:

class UserAccount(models.Model):
    reading_list = models.ManyToManyField('Book', through='ReadingList')

class ReadingList(models.Model):
    user = models.ForeignKey('UserAccount')
    title = models.CharField(max_length=100)
    book = models.ForeignKey('Book')
    # some other fields related to a reading list

Django doc about through keyword on M2M field.

By the way, don't use plural form on model names, django will add plural form when needed.

edited Jan 25 '16 at 19:11

answered Jan 25 '16 at 19:06

Shang Wang

24,909
20
73
94

Thanks for the tip. Thats where I was little confused. Where the ManyToMany goes in regards to connection. I thought that if the User is the parent the ManyToMany goes on the child. – Corey Gumbs Jan 25 '16 at 19:18
It goes either way, but do you think it makes more sense logically to get a reading list from user or from a book? – Shang Wang Jan 25 '16 at 19:24
Logically from the user. lol Ok I appreciate your help and am going to look at what you recommended. They say the first answer is usually right and in my planning I though the "through" option was my first choice. – Corey Gumbs Jan 25 '16 at 19:40

Making a reading list and confused about ManyToMany relationship between the models - Django

1 Answers1