Redis python-rom 对象过期。

Question

I am working with flask and redis. I've decided to try the rom redis orm ( http://pythonhosted.org/rom/ ) to manage some mildly complex data structures. I have a list of objects, lets say:

urls = ['www.google.com', 'www.example.com', 'www.python.org']

I also have the rom model:

class Stored_url(rom.Model):
    url = rom.String(required=True, unique=True, suffix=True)
    salt = rom.String()
    hash = rom.String()
    created_at = rom.Float(default=time.time)

This appears to be working on my dev setup. In my situation, i would like to start from scratch every day with some of the data and would like to set an expiration time for some objecta. I've looked through the documentation at http://pythonhosted.org/rom/rom.html# , but have not found a reference to expiration except in request caching. Is there a way to allow rom objects to expire?

Answer 1

Rom does not offer a built-in method automatic to automatically expire data. This is on purpose. I have explained the reasons why on 3 previous occasions:

• https://github.com/josiahcarlson/rom/issues/40
• https://github.com/josiahcarlson/rom/pull/47
• https://github.com/josiahcarlson/rom/issues/62

TL;DR; Redis does not offer the internal mechanisms necessary to make this automatic (triggers). I provide 2 workarounds in the pull request linked above.

Answer 2

From rom documentation, it's better to create a new expire_at float column with index=True, the column can store when the entity is to expire. Then to expire the data, you can use: Model.query.filter(expire_at=(0, time.time())).limit(10) to (for example) get up to the 10 oldest entites that need to be expired.

https://josiahcarlson.github.io/rom/rom.html#expiring-models-ttls