Constructor
new Client(options)
Creates a new
Client instance.
Parameters:
Name |
Type |
Description |
options |
DseClientOptions
|
The options used to create the client instance. |
Example
const dse = require('dse-driver');
const client = new dse.Client({
contactPoints: ['h1', 'h2'],
keyspace: 'ks1',
graphOptions: { name: 'graph1' }
});
const query = 'SELECT email, last_name FROM users WHERE key=?';
client.execute(query, ['guy'], function(err, result) {
assert.ifError(err);
console.log('User email ' + result.first().email);
});
Extends
Members
Gets an associative array of cluster hosts.
Type:
- Overrides:
keyspace :String
Gets the name of the active keyspace.
Type:
- Overrides:
Gets the schema and cluster metadata information.
Type:
- Overrides:
Methods
batch(queries, optionsopt, callback)
Executes batch of queries on an available connection to a host.
Parameters:
Name |
Type |
Attributes |
Description |
queries |
Array.<string>
|
Array.<{query, params}>
|
|
The queries to execute as an Array of strings or as an array
of object containing the query and params |
options |
QueryOptions
|
<optional>
|
|
callback |
ResultCallback
|
|
Executes callback(err, result) when the batch was executed |
- Overrides:
connect(callback)
Tries to connect to one of the contactPoints and discover the nodes of the cluster.
If the Client is already connected, it immediately invokes callback.
Parameters:
Name |
Type |
Description |
callback |
function
|
The callback that is invoked when a connection pool is created to at least one node
or it has failed to connect. |
- Overrides:
connect(callback)
Tries to connect to one of the contactPoints and discover the nodes of the cluster.
If the Client is already connected, it immediately invokes callback.
Parameters:
Name |
Type |
Description |
callback |
function
|
The callback is invoked when the pool is connected
(or at least 1 connected and the rest failed to connect) or it is not possible to connect |
- Overrides:
eachRow(query, paramsopt, optionsopt, rowCallback, callbackopt)
Executes the query and calls rowCallback for each row as soon as they are received.
Calls final callback after all rows have been sent, or when there is an error.
The query can be prepared (recommended) or not depending on QueryOptions.prepare flag. Retries on multiple
hosts if needed.
Parameters:
Name |
Type |
Attributes |
Description |
query |
String
|
|
The query to execute |
params |
Array
|
Object
|
<optional>
|
Array of parameter values or an associative array (object) containing parameter names
as keys and its value. |
options |
QueryOptions
|
<optional>
|
|
rowCallback |
function
|
|
Executes rowCallback(n, row) per each row received, where n is the row
index and row is the current Row. |
callback |
function
|
<optional>
|
Executes callback(err, result) after all rows have been received.
When dealing with paged results, ResultSet#nextPage() method can be used
to retrieve the following page. In that case, rowCallback() will be again called for each row and
the final callback will be invoked when all rows in the following page has been retrieved.
|
- Overrides:
Examples
Using per-row callback and arrow functions
client.eachRow(query, params, { prepare: true }, (n, row) => console.log(n, row), err => console.error(err));
Overloads
client.eachRow(query, rowCallback);
client.eachRow(query, params, rowCallback);
client.eachRow(query, params, options, rowCallback);
client.eachRow(query, params, rowCallback, callback);
client.eachRow(query, params, options, rowCallback, callback);
execute(query, paramsopt, optionsopt, callback)
Executes a query on an available connection.
The query can be prepared (recommended) or not depending on QueryOptions.prepare flag. Retries on multiple
hosts if needed.
Parameters:
Name |
Type |
Attributes |
Description |
query |
String
|
|
The query to execute |
params |
Array
|
Object
|
<optional>
|
Array of parameter values or an associative array (object) containing parameter names
as keys and its value |
options |
QueryOptions
|
<optional>
|
|
callback |
ResultCallback
|
|
Executes callback(err, result) when finished |
- Overrides:
executeGraph(query, parametersopt, optionsopt, callback)
Executes a graph query.
Parameters:
Name |
Type |
Attributes |
Description |
query |
String
|
|
The gremlin query. |
parameters |
Object
|
null
|
<optional>
|
An associative array containing the key and values of the parameters. |
options |
GraphQueryOptions
|
null
|
<optional>
|
The graph query options. |
callback |
function
|
|
Function to execute when the response is retrieved, taking two arguments:
err and result . |
- Overrides:
Examples
// Getting the first item (vertex, edge, scalar value, ...)
client.executeGraph('g.V()', function (err, result) {
assert.ifError(err);
const vertex = result.first();
console.log(vertex.label);
});
// Using result.forEach()
client.executeGraph('g.V().hasLabel("person")', function (err, result) {
assert.ifError(err);
result.forEach(function(vertex) {
console.log(vertex.type); // vertex
console.log(vertex.label); // person
});
});
// Using ES6 for...of
client.executeGraph('g.E()', function (err, result) {
assert.ifError(err);
for (let edge of result) {
console.log(edge.label); // created
// ...
});
});
getReplicas(keyspace, token) → {Array}
Gets the host list representing the replicas that contain such partition.
Parameters:
Name |
Type |
Description |
keyspace |
String
|
|
token |
Buffer
|
|
- Overrides:
Returns:
-
Type
-
Array
shutdown(callbackopt)
Closes all connections to all hosts
Parameters:
Name |
Type |
Attributes |
Description |
callback |
function
|
<optional>
|
|
- Overrides:
stream(query, paramsopt, optionsopt, callbackopt) → {types.ResultStream}
Executes the query and pushes the rows to the result stream
as soon as they received.
Calls callback after all rows have been sent, or when there is an error.
The stream is a Readable Streams2 object
that contains the raw bytes of the field value.
It can be piped downstream and provides automatic pause/resume logic (it buffers when not read).
The query can be prepared (recommended) or not depending on QueryOptions.prepare flag. Retries on multiple
hosts if needed.
Parameters:
Name |
Type |
Attributes |
Description |
query |
String
|
|
The query to prepare and execute |
params |
Array
|
Object
|
<optional>
|
Array of parameter values or an associative array (object) containing parameter names
as keys and its value |
options |
QueryOptions
|
<optional>
|
|
callback |
function
|
<optional>
|
executes callback(err) after all rows have been received or if there is an error |
- Overrides:
Returns:
-
Type
-
types.ResultStream
Events
hostAdd
Emitted when a new host is added to the cluster.
- Host The host being added.
- Overrides:
hostDown
Emitted when a host in the cluster changed status from up to down.
- host The host that changed the status.
- Overrides:
hostRemove
Emitted when a host is removed from the cluster
- Host The host being removed.
- Overrides:
hostUp
Emitted when a host in the cluster changed status from down to up.
- host The host that changed the status.
- Overrides: