Re: About proper use of mantissa.sharing...

On 30 Mar, 09:00 am, [email protected] wrote:
>Since I'm returning this ThemedElement (adapted from Foo) from a
>renderer, I find myself sometimes doing things like this, which simply
>feel wrong:

Hi Alex!  Sorry it's been a while.
>class Whatever(ThemedElement):
>   def renderFoo(self, request, tag):
>       # Supposing I want to put this item in the app store...
>       _store =3D
>self.original.store.parent.filesdir.child('app').child('Bar.axiom')).open()
>
>       # and whereas userStore is inmemory()... I feel like there's
>       # something very wrong with this idiom
>       return ixmantissa.INavigableFragment(model.Foo(store=3D_store,
>userStore=3Dself.original.store))
>   page.renderer(renderFoo)

The key problem with this is: don't render items in the app store.  You =

should try to never use store.parent in your application code.  The few =

places you really do need to use it, you should be aware that this is =

because of a missing feature in the infrastructure; in a few months, =

there should be literally zero places that these sorts of links are =

required.

One question: why an app store and not the user store?  I don't =

understand your use case at all, so I can't really offer a solution (or =

even point to all of the relevant open tickets: this is a sticky area of =

the infrastructure that we are actively cleaning up).

Unfortunately the real, "good" way to do this is blocked on the =

resolution of http://divmod.org/trac/ticket/2191 which I am having =

trouble finding time to work on.  Soon, though: it is my highest Divmod =

coding priority.

I believe you're also going to need this: =

http://divmod.org/trac/ticket/2554 which I need to review.  This would =

allow you to use items in app stores according to normal sharing rules; =

right now they have kind of wonky requirements.

Once those tickets are resolved, you can do something like what I =

describe below.  Hopefully you can either help us resolve them somehow =

or do something that is similar in spirit to this summary until they're =

done.

First of all, don't create any items in a renderer.  Ever.  Why would =

you do that?  Don't.  This has nothing to do with app stores or user =

stores; this is basic model/view separation stuff.

If you really, really need to render an app store item in a user store, =

create an item in the user store which links to the item in the app =

store with the relevant pieces of information.  In the future, you =

should create this item by sending a message to the app store.  For =

right now, fake that by doing something simple in the model that uses =

self.store.parent.

However, think about who owns the data; if you billed for every bit in =

your system, are you billing it to the application, or is it owned by a =

particular user?  Examples of data billed to a user: their blog posts, =

their emails, status updates, inventory records, etc.  Billed to the =

application: indexes, data that is placed on the front page of a public =

site, aggregations (top ten lists, etc).  Most of the time, the link =

actually goes the other way: items in an app store ought to be shallow =

copies, and pointers to, relevant information owned by a particular =

user.  For example, keep in mind that users don't need to be simply end- =

users either, you could make a user like "north american continent" if =

it's convenient.
>class FooElement(ThemedElement):
>   def foo(self):
>       primaryRole =3D sharing.getSelfRole(self.original.userStore)
>       #of course, the above won't work for the unauthenticated user...
>
>       _query =3D self.original.store.query(model.Bar)
>       return [post.toDict() for post in
>               sharing.asAccessibleTo(primaryRole, _query)]
>   athena.expose(foo)
>
>components.registerAdapter(
>   FooElement,
>   model.Foo,
>   ixmantissa.INavigableFragment
>)
>
>Anyone have suggestions about this?
>--
>Alex
>
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