使用 Flask 和 SQLAlchemy 返回存储在数据库中的 integer 变量的总和？

Question

I am creating an app using Flask and SQLAlchemy to track scores on a test for users. The User Model includes an Integer variable 'Score'. I want to add up the scores of all my registered users to produce an average score, but I am very new to Flask and unsure how to achieve it.

models.py

class User(UserMixin, db.Model):
#...
score = db.Column(db.Integer(), default = 0)

I would like to add the scores of all the different users and assign this value to a variable which i can then print out in one of my templates. I've tried everything I can think of but don't know how to iterate through the score of each user and then add that accumulatively to the total_score variable.

I have tried

total_score = User.query.filter_by(User.score).first()

But feel like I am way off with this. Would really appreciate any help on this thanks!

Answer 1

To get a single value representing the average score of all your users you can do something like this:

total_score = db.session.query(db.func.avg(User.score)).scalar()

Then you can pass it to your template something like this:

@app.route("/")
def route_name():
    total_score = db.session.query(db.func.avg(User.score)).scalar()

    return render_template("your-template.html", total_score=total_score)

Using db.func.avg we take the average of the score column and scalar gives us a single value back.

https://docs.sqlalchemy.org/en/13/core/functions.html