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Re: [IndexedDB] Passing an empty array to IDBDatabase.transaction

From: Jonas Sicking <jonas@sicking.cc>
Date: Fri, 14 Oct 2011 15:57:07 -0700
Message-ID: <CA+c2ei-y4QMzu3DmU0OG-a_O2oUjZQZQiR5jd_bL7EXz-+PBKw@mail.gmail.com>
To: Israel Hilerio <israelh@microsoft.com>
Cc: "ben turner (bent.mozilla@gmail.com)" <bent.mozilla@gmail.com>, "public-webapps@w3.org" <public-webapps@w3.org>, Tom Bolds <thombo@microsoft.com>, Adam Herchenroether <aherchen@microsoft.com>, Victor Ngo <vicngo@microsoft.com>
On Fri, Oct 14, 2011 at 2:57 PM, Israel Hilerio <israelh@microsoft.com> wrote:
> On Friday, October 14, 2011 2:43 PM, Jonas Sicking wrote:
>> On Fri, Oct 14, 2011 at 2:27 PM, Israel Hilerio <israelh@microsoft.com>
>> wrote:
>> > On Monday, October 10, 2011 10:15 AM, Israel Hilerio wrote:
>> >> On Monday, October 10, 2011 9:46 AM, Jonas Sicking wrote:
>> >> > On Fri, Oct 7, 2011 at 11:51 AM, Israel Hilerio
>> >> > <israelh@microsoft.com>
>> >> > wrote:
>> >> > > On Thursday, October 06, 2011 5:44 PM, Jonas Sicking wrote:
>> >> > >> Hi All,
>> >> > >>
>> >> > >> In both the Firefox and the Chrome implementation you can pass
>> >> > >> an empty array to IDBDatabase.transaction in order to create a
>> >> > >> transaction which has a scope that covers all objectStores in
>> >> > >> the database. I.e. you can do something like:
>> >> > >>
>> >> > >> trans = db.transaction([]);
>> >> > >> trans.objectStore(<any objectstore here>);
>> >> > >>
>> >> > >> (Note that this is *not* a dynamic scoped transaction, it's
>> >> > >> still a static scope that covers the whole database).
>> >> > >>
>> >> > >> In other words, these implementations treat the following two
>> >> > >> lines as
>> >> > >> equivalent:
>> >> > >>
>> >> > >> trans = db.transaction([]);
>> >> > >> trans = db.transaction(db.objectStoreNames);
>> >> > >>
>> >> > >> This, however, is not specified behavior. According to the spec
>> >> > >> as it is now the transaction should be created with an empty scope.
>> >> > >>
>> >> > >> I suspect both Mozilla and Google implemented it this way
>> >> > >> because we had discussions about this syntax on the list.
>> >> > >> However apparently this syntax never made it into the spec. I don't
>> recall why.
>> >> > >>
>> >> > >> I'm personally not a big fan of this syntax. My concern is that
>> >> > >> it makes it easier to create a widely scoped transaction which
>> >> > >> has less ability to run in parallel with other transactions,
>> >> > >> than to create a transaction with as narrow scope as possible.
>> >> > >> And passing
>> >> > db.objectStoreNames is always possible.
>> >> > >>
>> >> > >> What do people think we should do? Should we add this behavior
>> >> > >> to the spec? Or are implementations willing to remove it?
>> >> > >>
>> >> > >> / Jonas
>> >> > >>
>> >> > >
>> >> > > Our implementation interprets the empty array as an empty scope.
>> >> > > We
>> >> > allow the transaction to be created but we throw a NOT_FOUND_ERR
>> >> > when trying to access any object stores.
>> >> > > I vote for not having this behavior :-).
>> >> >
>> >> > Hi Israel,
>> >> >
>> >> > I just realized that I might have misinterpreted your response.
>> >> >
>> >> > Are you saying that you think that passing an empty-array should
>> >> > produce a transaction with an empty scope (like in IEs
>> >> > implementation and as described by the spec currently), or a
>> >> > transaction with every objectStore in scope (like in Firefox and chrome)?
>> >> >
>> >> > / Jonas
>> >> >
>> >>
>> >> We don't do it like FF or chrome.  We create the transaction but it
>> >> has an empty scope transaction.  Therefore, whenever you try to
>> >> access an object store we throw an exception.  Based on what Hans
>> >> said, it seems we're all in agreement.
>> >>
>> >> Also, I like Ben's suggestion of not allowing these transactions to
>> >> be created in the first place and throwing an exception during their
>> creation.
>> >>
>> >> Israel
>> >>
>> >
>> > What type of exception should we throw when trying to create a transaction
>> with an empty scope (NotFoundError, TypeError, or other)?
>>
>> Either of those would work for me.
>>
>> / Jonas
>
> We would like to go with NotFoundError.  The reason is that an empty array is still the correct type and therefore a TypeError would seem strange.

Just noticed "InvalidAccessError" which seems like it could be a good fit too.

/ Jonas
Received on Friday, 14 October 2011 22:58:12 GMT

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