Getting Started

Configuring a Traversal Execution Profile

The DSE Graph extension takes advantage of execution profiles to allow different configurations for the various query handlers.

You can specify the default execution profile to set the graph name and any graph option and use it like in the following example:

const { Client, ExecutionProfile } = require('cassandra-driver');
const dseGraph = require('cassandra-driver-graph');

const client = new Client({
  contactPoints: ['host1', 'host2'],
  localDataCenter: 'my_graph_dc',
  profiles: [
    new ExecutionProfile('default', { graphOptions:  { name: 'my_graph' } })
  ]
});

const g = dseGraph.traversalSource(client);
// Print the names of john's friends
g.V().has('name','john').out('friends').values('name').toList()
  .then(names => names.forEach(console.log));

If you have multiple execution profiles, you can also specify it when obtaining the TraversalSource instance:

const g = dseGraph.traversalSource(client, { executionProfile: 'graph-oltp2' });

Visit the Execution Profiles documentation and the Execution Profile API docs on the DataStax driver for more information.

Graph Traversal Executions via a DataStax Driver Client

Queries generated from Traversal can also be explicitly executed using the existing client.executeGraph() method on the Driver. executeGraph() method returns results using DSE Graph types. If you are familiar to driver query execution, you might prefer that way.

To generate the query from the traversal, use the queryFromTraversal() method:

const query = dseGraph.queryFromTraversal(g.V().hasLabel('person'));

For the DataStax driver to properly execute a query generated from a Traversal, you must use an Execution Profile generated using createExecutionProfile() method.

const client = new Client({
  contactPoints: ['host1', 'host2'],
  localDataCenter: 'my_graph_dc',
  profiles: [
    dseGraph.createExecutionProfile('explicit-exec-graph1')
  ]
});

const g = dseGraph.traversalSource(client);

const query = dseGraph.queryFromTraversal(g.V().hasLabel('person'));
// Reference the execution profile previously created.
client.executeGraph(query, null, { executionProfile: 'explicit-exec-graph1' })
  .then(result => {
    for (const vertex of result) {
      console.log(vertex.label); // person
      console.log(vertex instanceof cassandra.datastax.Graph.Vertex); // true
    }
  });

Putting it all together

const { Client, ExecutionProfile } = require('cassandra-driver');
const dseGraph = require('cassandra-driver-graph');
const client = new Client({
  contactPoints: ['host1', 'host2'],
  localDataCenter: 'my_graph_dc',
  profiles: [
    new ExecutionProfile('default', { graphOptions:  { name: 'my_graph' } }),
    dseGraph.createExecutionProfile('explicit-exec', { graphOptions:  { name: 'my_graph' } } )
  ]
});

// Obtain a traversal source
const g = dseGraph.traversalSource(client);

// Execute queries using the Traversal toList() method
g.V().hasLabel('person').values('age').toList()
  .then(ages => ages.forEach(console.log));

// Alternatively you can convert a given traversal to a string query and use 
// the DataStax driver executeGraph() method
const query = dseGraph.queryFromTraversal(g.V().hasLabel('person').values('age'));
// Reference the execution profile previously created.
client.executeGraph(query, null, { executionProfile: 'explicit-exec' })
  .then(result => console.log(result.toArray()));