ORM query many to many to one, Flask sql-alchemy - sql

Question

I have three flask-sqlalchemy-models. Books - unique entries by admin:
class Book(db.Model):
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
book_name = db.Column(db.String(20), unique=True, nullable=False)
def __repr__(self):
return self.book_name
Bookscomp - entries by users, related to above:
class Bookscomp(db.Model):
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
book = db.Column(db.Integer, db.ForeignKey('book.id'))
Company - user, related to above:
class Company(db.Model):
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
name = db.Column(db.String(100), nullable=False)
books = db.relationship('Bookscomp', secondary=companybook, lazy='dynamic',
backref=db.backref('company'))
companybook = db.Table('companybook',
db.Column('companyid', db.Integer, db.ForeignKey('company.id'), primary_key=True),
db.Column('bookid', db.Integer, db.ForeignKey('bookscomp.id'), primary_key=True),
)
Problem: I am trying to get book_name from Book model, through Company + Bookscomp.
So a company has many books and each book has reference to general book info.
Tried like this:
company = OrganizatCompanyion.query.filter_by(id=comp.id).first()
books = company.books.all()
for item in books:
print(item.book.book_name)
#AttributeError: 'int' object has no attribute
print(item.book)
#Gives book id from book model, but I need name
Why I cannot get book_name in the above code snippet directly? And how would it be best to achieve this?

Answer 1

You haven't defined a relationship between Book and Bookcomp so when you ask for item.book-- it's getting the book = db.Column(db.Integer... value. Maybe tweak your Bookscomp model to be something like:
class Bookscomp(db.Model):
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
book_id = db.Column(db.Integer, db.ForeignKey('book.id'))
book = db.relationship('Book')