[Kde-pim] Re: Availability of attributes

[Christian Mollekopf]

On Monday 07 March 2011 10:37:52 Kevin Krammer wrote:
> On Monday, 2011-03-07, Christian Mollekopf wrote:
> > On Monday 07 March 2011 09:30:40 Kevin Krammer wrote:
> > > On Monday, 2011-03-07, Christian Mollekopf wrote:
> > > > On Monday 07 March 2011 08:44:15 Kevin Krammer wrote:
> > > > > On Monday, 2011-03-07, Christian Mollekopf wrote:
> > > > > > Hi,
> > > > > > 
> > > > > > I need to know in the trash job, if an item/collection already
> > > > > > has an attribute or not. I know that I have to fetch the
> > > > > > attribute if I need the content of the attribute, but I'm not
> > > > > > sure if I need to fetch it as well if I just need to know if the
> > > > > > entity has the attribute using:
> > > > > > 
> > > > > > item.hasAttribute<Akonadi::EntityDeletedAttribute>()
> > > > > 
> > > > > It depends on how you got the item.
> > > > > 
> > > > > If you created the item locally and did not add the attribute
> > > > > yourself, you have no way of knowing whether someone else has added
> > > > > it.
> > > > > 
> > > > > If you got the item through a monitor, you can use the monitor's
> > > > > item fetch scope to make sure if gets the attribute if it exists.
> > > > 
> > > > Ok, so you're saying that if the item was fetched with a normal
> > > > monitor, NOT having:
> > > > 
> > > > fetchjob->fetchScope().fetchAttribute<EntityDeletedAttribute>(true);
> > > > 
> > > > set, It is also not possible to check if the item has the attribute.
> > > 
> > > Right. Your process doesn't have direct access to the Akonadi server
> > > backend, so the only way to get data is to ask the server.
> > > 
> > > > Is there any possibility for me to differentiate between  "Item
> > > > doesn't have this attribute" <-> "We don't know if the item has the
> > > > attribute or not"?
> > > 
> > > If you have tried fetching the attribute (implicitly through a monitor
> > > or explicitly through an item fetch job) and it is not availale then
> > > it's "item doesn't have this attribute".
> > 
> > Clear
> > 
> > > If you haven't attempted attribute fetching in any form it is "We don't
> > > know if the item has the attibute or not".
> > > 
> > > so
> > > 
> > > if ( item.isValid() && !item.hasAttribute<EntityDeletedAttribute>(() )
> > > // doesn't have
> > 
> > But if i fetch the item without having
> > fetchScope().fetchAttribute<Attribute>(true) set, I have an item which is
> > valid, but doesn't have the attribute, no?
> 
> Right, my bad.
> 
> > Or can I always check if the attribute is available, if the item is
> > valid, and just need to fetch the attribute (trought the monitor or
> > explicitly) if I want to access the content of the attribute? (Which was
> > my initial question)
> 
> No, you need to attempt getting the attribute before you can decide whether
> it exists or not.

Ok, thanks for your help.

Cheers,

Chris

> 
> Cheers,
> Kevin
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