[Kde-pim] Re: Akonadi resource: How to update item if backend data changed

[David Jarvie]

On Sun, June 5, 2011 3:12 pm, rgruber at users.sourceforge.net wrote:
> Hello!
>
> I've started to write an Akonadi resource that provides me access to the
> MS Exchange calendar that I'm forced to use at work. Using libmapi as
> backend everything worked out very well so far. I'm already able to create
> a collection for the Exchange calendar and fill the collection with all
> the events from the Exchange calendar. I can even do incremental addition
> of new items when new events get added to the Exchange calendar. And I
> also prepared some code for handling events that got deleted.
>
> But I'm stuck right now when an event on the Exchange calendar changed. I
> can easily find the changed items by checking the Akonadi items's
> modification time with the modification time reported by the exchange
> server. But I don't know how to get Akonadi to update the item's payload
> just like it does for new items.
>
> I choose the way where I create almost empty items in retrieveItems() and
> fetch the payload when Akonadi calls retrieveItem() of my resource. This
> works like a charm for new items. I pass them to
> itemsRetrievedIncremental() and Akonadi will call retrieveItem() where I
> fetch the payload from the Exchange server. But when I pass an Item to
> itemsRetrievedIncremental() that is already in the Akonadi store the
> retrieveItem() method never gets called. I tried to trick Akonadi by
> clearing the payload or changing the modification time of the item. But I
> did not manage to get retrieveItem() called for an already existing item.
>
>
> I checked the Akonadi tutorials and API doc but could not really find any
> info on how to react if backend data changes.
> So I hope that somebody can push for me in the right direction. I've
> uploaded the relevant parts of my resource to pastbin. So you can have a
> look what I've got so far: http://paste.kde.org/78673/  The problem arises
> at line 60 where I found a changed item and don't know what do do with
> it...
>
> Is there a proposed way of handling backend data changes?
> If I change an item (e.g. the modification time) and pass it to
> itemsRetrievedIncremental() why are the changes not written to the Akonadi
> store? or am I missing something here?

You need to use ItemModifyJob to tell Akonadi to change an existing Item.
itemsRetrievedIncremental() is only for use inside retrieveItem().

-- 
David Jarvie.
KDE developer.
KAlarm author - http://www.astrojar.org.uk/kalarm

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