[Nepomuk] Re: How to detect new/removed tags from a Soprano::Statement?

[Laura Dragan]

On Thursday 17 February 2011 16:32:45 Christian Mollekopf wrote:
> Hey Laura,
> 
> On Thursday 17 February 2011 14:10:58 Laura Dragan wrote:
> > Hi Chris,
> > 
> > On Thursday 17 February 2011 01:14:02 Christian Mollekopf wrote:
> > > hi,
> > > 
> > > Does anybody know how I can detect when a new Tag was added/removed
> > > to/from Nepomuk? I.e. to update a Tag Cloud.
> > 
> > do you need to update the tag cloud if any resource is tagged outside your
> > app, or just inside your app?
> > 
> I'd like to update it whenever new tags are available, not only from within my 
> app.
> 
> > In SemNotes for instance the tag cloud is built only with the tags used on
> > the notes - you can find that code on gitorious.
> > 
> > A long time ago I wrote a plasmoid that built the tagcloud for the entire
> > desktop (not sure if it's in playground or not), and that one was
> > listening to statementsAdded and statementsRemoved from the model, but I
> > took the easy path and rebuilt the cloud every time instead of just
> > updating it. It worked ok with up to 30 tags, without visible delays from
> > all the repository querying.
> > 
> > > Currently I listen to the statementAdded/statementRemoved signals of the
> > > Soprano::Model, and I can also detect if an Item gets a new Tag, but I
> > > don't know how I can see from the Statement when a new Tag was created
> > > or a Tag was deleted.
> > 
> > I think you can use the signals
> > 
> > void statementAdded( const Soprano::Statement &statement)
> > void statementRemoved( const Soprano::Statement &statement)
> > 
> > to look into the statements that are affected with the functions:
> > subject(), predicate() and object().
> > 
> Thats what I'm trying to do, but I don't get what indicates that a tag is new 
> to the Nepomuk system (or that a tag was removed).

I'd do that by checking if the statement added or removed has the predicate "rdf:type" and the object "nao:Tag". The subject of the statement is then the uri of the tag that was created or deleted.

Laura

> 
> Thanks for your help,
> 
> Chris
> > 
> > Hope this helps
> > Laura
> > 
> > > Cheers,
> > > 
> > > Chris
> > > _______________________________________________
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> > > Nepomuk at kde.org
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> > 
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