Josh Patton Josh Patton - 1 year ago 65
Python Question

Possible Data Schemes for Achievements on Google App Engine

I'm building a flash game website using Google App Engine. I'm going to put achievements on it, and am scratching my head on how exactly to store this data. I have a (non-google) user model. I need to know how to store each kind of achievement (name, description, picture), as well as link them with users who earn them. Also, I need to keep track of when they earned it, as well as their current progress for those who don't have one yet.

If anyone wants to give suggestions about detection or other achievement related task feel free.


Non-Google User Model:

class BeardUser(db.Model):
email = db.StringProperty()
username = db.StringProperty()
password = db.StringProperty()
settings = db.ReferenceProperty(UserSettings)
is_admin = db.BooleanProperty()
user_role = db.StringProperty(default="user")
datetime = db.DateTimeProperty(auto_now_add=True)

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Answer Source

Unless your users will be adding achievements dynamically (as in something like Kongregate where users can upload their own games, etc), your achievement list will be static. That means you can store the (name, description, picture) list in your main python file, or as an achievements module or something. You can reference the achievements in your dynamic data by name or id as specified in this list.

To indicate whether a given user has gotten an achievement, a simple way is to add a ListProperty to your player model that will hold the achievements that the player has gotten. By default this will be indexed so you can query for which players have gotten which achievements, etc.

If you also want to store what date/time the user has gotten the achievement, we're getting into an area where the built-in properties are less ideal. You could add another ListProperty with datetime properties corresponding to each achievement, but that's awkward: what we'd really like is a tuple or dict so that we can store the achievement id/name together with the time it was achieved, and make it easy to add additional properties related to each achievement in the future.

My usual approach for cases like this is to dump my ideal data structure into a BlobProperty, but that has some disadvantages and you may prefer a different approach.

Another approach is to have an achievement model separate from your user model, and a ListProperty full of referenceProperties to all the achievements that user has gotten. this has the advantage of letting you index everything very nicely but will be an additional API CPU cost at runtime especially if you have a lot of achievements to look up, and operations like deleting all a user's achievements will be very expensive compared to the above.

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