Flask SQLAlchemy查询beetwen 2表

Question

I'm trying to create query like:

SELECT Book.title, Opinion.body  
FROM Book,Opinion  
WHERE Opinion.book_id = Book.id

but in SQLAlchemy. I want to show all opinions for book and display it on web page.

models.py:

class Opinion(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    body = db.Column(db.String(140))
    timestamp = db.Column(db.DateTime, index=True, default=datetime.utcnow)
    user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
    book_id = db.Column(db.Integer, db.ForeignKey('book.id'))

    def __repr__(self):
        return '<Post {}'.format(self.body)

class Book(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String(255), index=True)
    description = db.Column(db.String(255))
    author = db.Column(db.String(255))
    pages = db.Column(db.Integer)
    opinions = db.relationship('Opinion', lazy='dynamic')

I can create query where is only return for 1 book, but not for all. I tried this:

result = Opinion.query(Book.id, Opinion.body).filter_by(Opinion.book_id = Book.id).all()

But it still doesnt work. Can someone help me with this?

Answer 1

@app.route('/detail_book/<title>')
def detail_book(title):
    book = Book.query.filter_by(title=title).first_or_404()
    result = db.session.query(Book.id,Opinion.body).filter(Opinion.book_id==book.id).filter(and_(Book.title == title)).all()
    return render_template('detail_book.html', book=book, result=result)

It works as it should

Answer 2

Alternatively you can query and render the results as shown below.

book = Book.query.get(book_id)
opinions = book.opinions.all()

In your templates render them as follows:

{{ book.title }}
{% for item in opinions %}
    {{ item.body }}
{% endfor %}