Shuffling SQLAlchemy results?
python, sqlalchemy
Solution
I'm not entirely sure of your concern. Is it that you'll be returning a large dataset, so large lists will be manipulated in memory?
If so, you can do it within the SQL statement if you're not overly worried about portability; i.e., if you are using MySQL, you can do:
from sqlalchemy.sql.expression import func
Item.query.order_by(func.rand()).offset(20).limit(10).all()
Or, in PostgreSQL:
from sqlalchemy.sql.expression import func
Item.query.order_by(func.random()).offset(20).limit(10).all()
Other databases have similar mechanisms, so the function called would depend on what you're targeting. And of course, if you are trying to write a general purpose app that can run on any of SQLAlchemy's backends, you might need to stick with the example provided.
Problem
The code in question: ``` random_items = random.shuffle(Item.query.all())[20:30] ``` It's in a Flask/SQLAlchemy app.`Item` is the model. That's what I'm doing right now and it works but I foresee a disaster when I start using a real dataset. How do I do this properly?