The first variant is faster while the second one requires less
maintenance if you rename your documents a lot. Both will do the job.
I'd use the first, de-normalised model unless you normally have a lot
of revisions per document, modify the common document meta-data quite
often, and the meta-data itself is large (in terms of the number of
bytes or the number of properties stored).
On Jan 13, 10:33 am, Ecir Hana <ecir.h...@gmail.com> wrote:
> Hello,
> what is the preferred way of retrieving the latest revision of a
> document?
> (The 'name' doesn't change across the revisions.)
>
> 1:
> class Document(db.Model):
> name = db.StringProperty()
> revision = db.IntegerProperty()
> content = db.TextProperty()
>
> latest = Document.all().filter('name =', some_name).order('-
> revision').get()
>
> 2:
> class Document(db.Model):
> name = db.StringProperty()
>
> class Revision(db.Model):
> document = db.ReferenceProperty(Document,
> collection_name='revisions')
> revision = db.IntegerProperty()
> content = db.TextProperty()
>
> document = Document.all().filter('name =', some_name).get()
> latest = document.revisions.order('-revision').get() [1]
>
> 3:
> something different altogether?
>
> [1] Is it ok to call .get() for the second time?
>
> Thanks in advance!
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