Defining an Entity Group

[Yagiz Erkan]

Hi,

Can somebody point me to a resource explaining how to define an entity
group please? The official doc
(http://code.google.com/appengine/docs/datastore/keysandentitygroups.html#Entity_Groups_Ancestors_and_Paths)
doesn't show much...

Thanks,

- Yagiz -

[g-man]

I'm just getting into that now, too...

Any news?

[David Symonds]

There really isn't anything more to it: by default, every entity is in
its own entity group; if you declare entity A to be the parent of
entity B, then B is in A's entity group instead of its own.

Dave.

[Yagiz Erkan]

Yes, I discovered that just after sending the message. I apologize...
Following the good netiquette I should've replied to my own message
for the others... which I usually do when my question is unanswered
but I forgot it this time...

Thanks Dave!

- Yagiz -

[g-man]

Hi,

My question is going to this:

Can different entity kinds be part of a group?

I have blog Items, and each Item can have Comments (which have a
ReferenceProperty to the 'parent' Item).

I want to delete an Item and all its Comments, so I thought an entity
group would be good to run in a transaction, otherwise if there was a
problem, I could be left with orphaned Comments (without an Item), or
an Item with missing Comments.

As I experiment with this, I'm not getting the entity group membership
set or acknowledged, and when I try the transaction, I get an error. I
fear that only entities of one kind can belong to a group, but what's
the good of that in my case, and how do I do my transaction with
safety otherwise?

Any ideas?

Thanks!

[David Symonds]

On Mon, Jul 7, 2008 at 8:25 AM, g-man <greg...@gmail.com> wrote:

> My question is going to this:
>
> Can different entity kinds be part of a group?

Yes, definitely.

> I have blog Items, and each Item can have Comments (which have a
> ReferenceProperty to the 'parent' Item).
>
> I want to delete an Item and all its Comments, so I thought an entity
> group would be good to run in a transaction, otherwise if there was a
> problem, I could be left with orphaned Comments (without an Item), or
> an Item with missing Comments.

Be aware that writes are transactionally serialised for the entity
group it is changing. If you're deleting, that's probably not an
issue, though.

Dave.