sparql-client

A simple sparql client written for Node.js (with compatibility for Apache Fuseki).

Version 0.2.0

Usage

###Querying###

var SparqlClient = require('sparql-client');
var util = require('util');
var endpoint = 'http://dbpedia.org/sparql';

// Get the leaderName(s) of the given citys
// if you do not bind any city, it returns 10 random leaderNames
var query = "SELECT * FROM <http://dbpedia.org> WHERE {
    ?city <http://dbpedia.org/property/leaderName> ?leaderName
} LIMIT 10";
var client = new SparqlClient(endpoint);
console.log("Query to " + endpoint);
console.log("Query: " + query);
client.query(query)
  //.bind('city', 'db:Chicago')
  //.bind('city', 'db:Tokyo')
  //.bind('city', 'db:Casablanca')
  .bind('city', '<http://dbpedia.org/resource/Vienna>')
  .execute(function(error, results) {
  process.stdout.write(util.inspect(arguments, null, 20, true)+"\n");1
});

###Formatting###

From version 0.2.0 it is possible to add options regarding the formating of the results. For example, we execute the following query (to retrieve all books and their genres).

PREFIX dbpedia-owl: <http://dbpedia.org/owl/>
SELECT ?book ?genre WHERE {
    ?book dbpedia-owl:literaryGenre ?genre
}

The default formatting (when no options are provided) results, for the bindings (limited to two results in our example), in

[{ book :
    {
        type: 'uri',
        value: 'http://live.dbpedia.org/page/A_Game_of_Thrones'
    },
    genre : {
        type: 'uri',
        value: 'http://live.dbpedia.org/page/Fantasy'
    }
}, { book :
    {
        type: 'uri',
        value: 'http://live.dbpedia.org/page/A_Game_of_Thrones'
    },
    genre : {
        type: 'uri',
        value: 'http://live.dbpedia.org/page/Political_strategy'
    }
}]

Using the format option resource with the resource option set to book results in

[{ book :
    {
        type: 'uri',
        value: 'http://live.dbpedia.org/page/A_Game_of_Thrones'
    },
    genre : [{
        type: 'uri',
        value: 'http://live.dbpedia.org/page/Fantasy'
    }, {
        type: 'uri',
        value: 'http://live.dbpedia.org/page/Political_strategy'
    }]
}]

This makes it easier to process the results later (in the callback), because all the genres are connected to one book (in one binding), and not spread over several bindings. Calling the execute function will look something like this

execute({format: 'resource', resource: 'book'}, function(error, results) {
  process.stdout.write(util.inspect(arguments, null, 20, true)+"\n");
});

License