Unable to create named graphs

[timmy....@gmail.com]

Hi,

I'm unable to create named graphs. I've tried to do this in the admin console and with the Jena API, but without luck.

Admin console: 

create graph <http://url.com/graph_name>

Jena code:

final Connection conn = ConnectionConfiguration.to(DATABASE_NAME).server(SNARL_URL).connect();

final Dataset dataset = SDJenaFactory.createDataset(conn);

dataset.begin(ReadWrite.WRITE);

dataset.addNamedModel("http://url.com/graph_name", ModelFactory.createDefaultModel());

// OR : final Model model = dataset.getNamedModel("http://url.com/graph_name");

dataset.commit();

Why doesn't this work out of the box? Thanks.

[timmy....@gmail.com]

A small update, I've tried the following line of code as well:

conn.graph("create graph <http://url.com/graph_namae>").execute();

but it seems to be buggy (or I'm totally not getting it :-))

java.lang.Boolean cannot be cast to org.openrdf.query.GraphQueryResult

[Mike Grove]

As mentioned in the docs [1], the `Connection#graph` method is for creating graph queries, not update queries.  For updates, you must use the `update` method.

Please note, there's no notion of a graph which exists, but is empty, in Stardog.  To "create" a named graph, simply add triples to it.

Cheers,

Mike

[1] http://docs.stardog.com/java/snarl/com/complexible/stardog/api/Connection.html#graph(java.lang.String) 

 

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[timmy....@gmail.com]

Understood, but the reason I tried Connection#Graph is because the update method did not create it as well. Also, I've had multiple occasions where Dataset#getModel("") returned a NullPointerException, before I could add triples.

Nevertheless, somehow, I've now got the graphs I needed. If I have more input, I'll add them to this topic.