Question 28: Consider the following Flask-SQLAlchemy models for a lib…

1from flask_sqlalchemy import SQLAlchemy
2
3db = SQLAlchemy()
4
5class Library(db.Model):
6    id = db.Column(db.Integer, primary_key=True)
7    name = db.Column(db.String(100), unique=True, nullable=False)
8    location = db.Column(db.String(200), nullable=False)
9    books = db.relationship('Book', backref='library_ref', lazy=True)
10
11class Author(db.Model):
12    id = db.Column(db.Integer, primary_key=True)
13    name = db.Column(db.String(80), nullable=False)
14    email = db.Column(db.String(120), unique=True, nullable=True)
15    books = db.relationship('Book', backref='author_ref', lazy=True)
16
17class Book(db.Model):
18    id = db.Column(db.Integer, primary_key=True)
19    title = db.Column(db.String(150), nullable=False)
20    isbn = db.Column(db.String(13), unique=True, nullable=False)
21    library_id = db.Column(db.Integer, db.ForeignKey('library.id'), nullable=False)
22    author_id = db.Column(db.Integer, db.ForeignKey('author.id'), nullable=False)
23    is_available = db.Column(db.Boolean, default=True)

1from flask import Flask, request, jsonify
2
3app = Flask(__name__)
4
5@app.route('/books/<int:library_id>', methods=['GET'])
6def get_library_books(library_id):
7    library = Library.query.get_or_404(library_id)
8    available_books = Book.query.filter_by(
9        library_id=library_id,
10        is_available=True
11    ).all()
12
13    result = []
14    for book in available_books:
15        result.append({
16            'id': book.id,
17            'title': book.title,
18            'author': book.author_ref.name,
19            'isbn': book.isbn
20        })
21
22    return jsonify({
23        'library': library.name,
24        'location': library.location,
25        'available_books': result
26    })