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List:       mozilla-rdf
Subject:    Re: Function to get data list from local RDF
From:       Neil Deakin <ndeakin () sympatico ! ca>
Date:       2003-10-14 16:40:39
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Josiah wrote:
> I am working on a project that utilizes RDF. The RDF file contains a
> list of IP address, similar to this form:
> 
> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>          xmlns:nc="http://www.foo.com/NC-rdf#">
>    <rdf:Description about="urn:root">
>        <nc:links>
>              <rdf:Seq>
>                      <rdf:li><rdf:Description nc:name="10.1.2.3"
> /></rdf:li>
>                      <rdf:li><rdf:Description nc:name="12.1.2.3"
> /></rdf:li>
>                      <rdf:li><rdf:Description nc:name="127.0.0.1"
> /></rdf:li>
>            </rdf:Seq>
>        </nc:links>
>    </rdf:Description>
> </rdf:RDF>
> 
> What I need to happen is when a user clicks a button, I need to call
> an external program one at a time for each of these IP addresses. I
> have been struggling with how to get these out of the RDF. Trying to
> use the RDF-in-Mozilla FAQ, and other group postings, I have come up
> with this.
> 
> var RDF=Components.classes["@mozilla.org/rdf/rdf-service;1"].getService();
> RDF = RDF.QueryInterface(Components.interfaces.nsIRDFService);
> var sourcename = "preferences.rdf";
> 
> var datasource=RDF.GetDataSource(sourcename);
> datasource.QueryInterface(Components.interfaces.nsIRDFDataSource);
> var links = RDF.GetResource("urn:root");
> var itr = datasource.ArcLabelsOut(links);
> while(itr.hasMoreElements()){
> 	var arcLabelOut = itr.getNext();
> 	// arcLabelOut has one IP address??
> }

That will return the single nc:links arc. You should use getTarget first

var target = ds.getTarget(links,
                RDF.GetResource("http://www.foo.com/NC-rdf#links"),true);

Then, you might want to use nsIRDFContainer and nsIRDFContainerUtils to 
iterate over a container.

> 
> This doesn't work, and doesn't look quite right to me. Am I on the
> right track?
> 
> Thanks,
> Josiah

/ Neil

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