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POSerializing models and resolving references with spira/RDF.rb
 

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  1. POSerializing models and resolving references with spira/RDF.rb
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    <p>I'm using <a href="https://github.com/ruby-rdf/spira" rel="nofollow">Spira</a> as a model/persistence layer for a Ruby application. I'm having trouble getting a suitable serialization (e.g., as RDF/XML) for my individual models. For example, when I dump a model that contains "associations", I get XML that looks like:</p> <pre class="lang-xml prettyprint-override"><code>&lt;ns0:video rdf:about="info:whatever/videos/g91832990"&gt; &lt;ns1:contributor rdf:resource="info:whatever/interviewees/g88129610"/&gt; &lt;ns1:title&gt;Test Video&lt;/ns1:title&gt; &lt;ns0:files rdf:resource="info:whatever/files/g91776800"/&gt; &lt;/ns0:video&gt; </code></pre> <p>However, I'd like this XML representation to resolve the <code>rdf:resource</code> references. That is, I'd like the XML to look more like this (which is what I get when I do a dump of the whole repository/triplestore):</p> <pre class="lang-xml prettyprint-override"><code>&lt;ns0:video rdf:about="info:repository/videos/g91832990"&gt; &lt;ns1:contributor&gt; &lt;ns2:person rdf:about="info:repository/interviewees/g88129610"&gt; &lt;ns2:name&gt;Creator&lt;/ns2:name&gt; &lt;/ns2:person&gt; &lt;/ns1:contributor&gt; &lt;ns1:title&gt;Test Video&lt;/ns1:title&gt; &lt;!-- ... --&gt; &lt;/ns0:video&gt; </code></pre> <p>The contributor element is expanded to contain the relevant metadata. I can get the first-level references with a SPARQL query like:</p> <pre class="lang-rb prettyprint-override"><code>sparql.construct([:o, :p2, :o2]).where([node, :p, :o], [:o, :p2, :o2]) </code></pre> <p>where node is my "about" node. However, I want to do this to arbitrary depth. I understand that this question might touch on bigger issues, like doing recursive queries in SPARQL/RDF. However, I was hoping there would be some switch or setting in Spira or RDF.rb that would just change the output format. </p> <p>Sorry about my terminology: I'm sure "resolving references" isn't the correct term to use.</p> <p><strong>EDIT</strong></p> <p>In Spira, models mixin <code>RDF::Enumerable</code>; they have an RDF representation comprising RDF statements from the triplestore where the <code>subject</code> is the model's URI. "Dumping a model" looks like:</p> <pre><code>v = Video.find 'RDF::Enumerable' v.dump(:rdfxml) </code></pre> <p>The RDF/XML generated contains only the model's RDF statements. It's also possible to dump the whole triplestore (e.g., my second example above) with the following command:</p> <pre><code>Spira.repository.dump(:rdfxml) </code></pre>
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    1. USJacob Brown
    1. USJacob Brown
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    1. COWhen you say that you "dump" the model, is it correct to assume that somewhere else in the output, there's a description of `info:whatever/interviewees/g88129610`?
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      1. POSerializing models and resolving references with spira/RDF.rb
      1. USJoshua Taylor
    2. CO@JoshuaTaylor, thanks for the response. If I'm understanding you correctly, the answer is no--the RDF/XML generated from dumping the model only contains statements where the subject is the model URI. However, the description for `info:whatever/interviewees/g88129610` does exist in the triplestore, and can be output with a separate query or a dump of the whole triplestore. I've added a little bit of detail above.
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      1. POSerializing models and resolving references with spira/RDF.rb
      1. USJacob Brown
    3. COAh, if the `dump` function there just returns a model containing triples whose subjects are the resource at hand, then you're right, that won't contain the descriptions of the other other resources that are related to it. It sounds like you might need to write something that does that for you. :\
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      1. POSerializing models and resolving references with spira/RDF.rb
      1. USJoshua Taylor
 

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