Hi Gabriel,
Ah, you're hitting the first bump in learning to think
non-relationally. Rather than creating 3 models, what about creating a List
of categories for each Podcast and just storing that on the podcast? The
tradeoff is that it won't be easy to rename a podcast category, but that
shouldn't be something that happens frequently.
When designing for the datastore, aim for designing for a key-value store
when possible, and don't think in terms of joins.
--
Ikai Lan
Developer Programs Engineer, Google App Engine
plus.ikailan.com | twitter.com/ikai
On Mon, Oct 3, 2011 at 2:30 AM, gabriel munteanu <jajali...@gmail.com>wrote:
> Hi,
>
> I have the following model [pseudo code]:
>
> db.Model("podcast", {
> name: StringProperty,
> description: TextProperty,
> homePageURL: StringProperty,
> addedDate: DateProperty
> });
>
> db.Model("category", {
> name: StringProperty,
> podcastsNumber: IntegerProperty
> });
>
> db.Model("podcastcategory", {
> category: ReferenceProperty({referenceClass: Category}),
> podcast: ReferenceProperty({referenceClass: Podcast})
> });
>
> I am trying to query the datastore to show in the web page the latest
> 5 podcasts in a certain category.
>
> Problem is my approach seems very costly:
>
> I do a query against podcastcategory and get al lentities there
> filtered by my category property.
> and i get all podcasts.
> then I would have to sort them in my app by addedDate.
>
> I feel that something is wrong, maybe my query or my data modelling. I
> would appreciate any advice or links to set me to the right direction.
>
> cheers,
> Gabi
>
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