thanks for your replies, especially yejun, that thread is very informative, not only now, but of a problem I could see coming when I need to transact a product from one user to another and money must also be updated on both users.
On Oct 10, 8:31 pm, yejun <[EMAIL PROTECTED]> wrote: > I found an old thread on this > topic.http://groups.google.com/group/google-appengine/browse_thread/thread/... > It seems eventual consistency is the only practical option. > > On Oct 9, 1:04 pm, David <[EMAIL PROTECTED]> wrote: > > > Hi, a question for all you datastore gurus: > > > If I have: > > > class User(db.Model): > > money = db.IntegerProperty(required=True) > > > class Thing(db.Model): > > cost = db.IntegerProperty(required=True) > > stuff = db.BlobProperty(required=True) > > > I need to allow a user to create a new thing and then reference the > > things they have somehow. So a request would be called with the cost > > and the blob data, and I would like to put a new Thing in the > > datastore. But heres the problem, only if the user has enough money to > > create the new Thing. > > > This is causing me a issue, as i cant update two separate entity > > groups in one transaction. unless im missing something i dont want to > > group them as the Thing may be sold at a later data to a new User. > > > so i need to: > > > 1)get the users money > > 2)if they have enough create the Thing and put it in the datastore > > 3)update the users money and reference the Thing to the user somehow > > and re-store > > > If any of this fails i need it all to roll back. > > > Currently im creating the Thing regardles and performing a transaction > > on the User, if this fails i delete the Thing after. This makes me > > uneasy :) > > > any suggestions would be most welcome. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to google-appengine@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~----------~----~----~----~------~----~------~--~---
