I second that. I have cases where I'm building a structure of multiple objects, and I have to do a put() just to get the id, and then I need to do another put() to the same object later on. Eliminating the 2nd put() of the same object in the flow would also allow me to wrap it in a transaction.
2009/6/16 Andy Freeman <ana...@earthlink.net>: > >> The decision to allow setting key_names but not IDs is something we may >> revisit. > > I hope that you're also considering some way to request and allocate > an unused id for a given path prefix. (That way we can get unique key > ids to specify.) > > > > On Jun 15, 4:45 pm, "Jeff S (Google)" <j...@google.com> wrote: >> Hi cryb, >> >> As you noted, we do not currently allow the ID for a key to be set, as we >> ensure that the ID is unique for each existing entity. I recommend using a >> key name instead of an ID, as Antoniov suggeted, if possible. >> >> It is technically possible to modify the key of an entity as it is being >> converted to a protocol buffer message before it is sent to the datastore. >> You could do this using hooks in the API proxy as described in this >> article:http://code.google.com/appengine/articles/hooks.htmlAlso it is >> possible to >> construct the key for the desired object if you know the ID in advance. >> >> class X(db.Model): >> pass >> >> # If you've already created the entity so you have the ID. >> x_id = X().put().id() >> >> # Instead of getting by ID, you can create the key manually. >> k = db.Key.from_path('X', x_id) >> >> Now you have the desired key without having fetched the object, but the part >> which the model class does not allow is setting the key yourself. So you >> could modify the protocol buffer message before it is written to the >> datastore, but I don't recommend it. >> >> The decision to allow setting key_names but not IDs is something we may >> revisit. >> >> Happy coding, >> >> Jeff >> >> 2009/6/12 cryb <cbuti...@gmail.com> >> >> >> >> >> >> > Hi.. that is to build key names... What I asked was why I can't build >> > a key ID.. >> >> > On Jun 12, 5:35 am, Antoniov <nio....@gmail.com> wrote: >> > > Use the code: >> > > s = Story(key_name="xzy123") >> > > Then you create an entity with the key name "xzy123". >> >> > > Check this: >> >http://code.google.com/intl/en-US/appengine/docs/python/datastore/key... >> >> > > On 6月12日, 上午1时28分, cryb <cbuti...@gmail.com> wrote: >> >> > > > Does anyone know why it is possible to build a key name but NOT a key >> > > > id? I know key IDs are used as autoincrements, but why can't I just >> > > > override this mechanism and build my own key id? >> > > > Suppose I want to overwrite an existent entry in my table that has a >> > > > key id I know, and also I want to keep that key id after update... >> > > > because I can't just build a key id, I am forced to fetch that entity, >> > > > modify it and write it back, instead of just write the updated entity >> > > > with the key id I already know - so an additional read to the >> > > > datastore. >> > > > Is there an obscure reason for that? (both key names and key ids are >> > > > prefixed with appid/kind as far as I know so there is no chance of >> > > > collision with other apps/kinds)- Hide quoted text - >> >> - Show quoted text - > > > --~--~---------~--~----~------------~-------~--~----~ 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 google-appengine+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~----------~----~----~----~------~----~------~--~---
