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https://jira.duraspace.org/browse/DS-1122?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=24111#comment-24111
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Tim Donohue commented on DS-1122:
---------------------------------
I've noticed there's another oddity with how "bitstream_order" already works.
If you create a brand new Bitstream in the system, it's sequence_id isn't set
until Item.update() is called. This means that the 'bitstream_order' doesn't
get set properly at all.
I just tried the following in the 1.8.1 XMLUI, and here's what happens:
* Create an Item that has two Bitstreams:
- Bitstream A (bitstream_order: 1, sequenceID: 1)
- Bitstream B (bitstream_order: 2, sequenceID: 2)
* Add a brand new Bitstream ('C') to this Item:
- Bitstream C (bitstream_order: -1, sequenceID: 3)
* Add another new Bitstream ('D') to this Item:
- Bitstream D (bitstream_order: -1, sequenceID: 4)
You'll notice the last two bitstreams end up with an order=-1, as the
'bitstream_order' field gets set before the sequence_id is ever initialized.
So, adding new Bitstreams in general causes a 'random' ordering of bitstreams
(as they always get set to 'bitstream_order'=-1 by default, until someone goes
in and manually reorders them)
> When adding a Bitstream to a Bundle, the 'bitstream_order' is always set to
> the 'sequence_id'
> ---------------------------------------------------------------------------------------------
>
> Key: DS-1122
> URL: https://jira.duraspace.org/browse/DS-1122
> Project: DSpace
> Issue Type: Bug
> Components: DSpace API
> Affects Versions: 1.8.0, 1.8.1
> Reporter: Tim Donohue
> Assignee: Tim Donohue
> Fix For: 1.8.2
>
> Attachments: Bundle.patch
>
>
> Currently, in the Bundle.addBitstream() method the 'bitstream_order' setting
> is always set to the same value as the 'sequence_id'.
> This makes a large assumption that these two fields should always be equal
> for newly created bitstreams.
> However, in scenarios where you are restoring an Item and its Bitstreams
> (like via AIP Backup & Restore), this assumption falls flat. In 'restore'
> scenarios, it's very possible you may want to restore the 'sequence_id' as 2
> while the 'bitstream_order' should be 1. Unfortunately, this becomes
> problematic, as the 'addBitstream()' method will always assume
> bitstream_order=sequence_id.
> My proposal is to instead implement Bundle.addBitstream() so that it is
> always *appending* the newly added bitstream to the end of the current list
> of Bitstreams. So, instead it should set:
> bitstream_order = bitstreams.size()
> This will work fine for 'restore' scenarios, as Bitstreams are always
> restored in order, so the bitstream_order may be restored to a different
> value to the sequence_id.
> A proposed patch to the Bundle class is attached. I've done some minimal
> testing so far, but it seems stable. I have verified that with this patch in
> place, I can now restore *both* an Item's bitstream_order and sequence_id to
> different values (as necessary), via the AIP Backup & Restore tools.
> I'd appreciate feedback on this approach.
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