@google-cloud/spanner 2.1.0 » Class: Session

Session

class

Create a Session object to interact with a Cloud Spanner session.

It is unlikely you will need to interact with sessions directly. By default, sessions are created and utilized for maximum performance automatically.

Constructor

Session

new Session(database, name)

Parameter
database	Database Parent Database instance.
name	Optional string The name of the session. If not provided, it is assumed you are going to create it.

Example

const {Spanner} = require('@google-cloud/spanner');
const spanner = new Spanner();

const instance = spanner.instance('my-instance');
const database = instance.database('my-database');

//-
// To create a session manually, don't provide a name.
//-
const session = database.session_();

session.create(function(err) {
  if (err) {
    // Error handling omitted.
  }

  // Session created successfully.
  // `session.id` = The name of the session.
});

//-
// To access a previously-created session, provide a name.
//-
const session = database.session_('session-name');

Property

id

string

Methods

beginTransaction

beginTransaction(options, callback) returns Promise containing BeginTransactionResponse

Begin a new transaction.

Parameter
options	Optional object Timestamp bound options.
callback	BeginTransactionCallback The callback function.

See also

BeginTransaction API Documentation

Returns

Promise containing BeginTransactionResponse 

Example

session.beginTransaction(function(err, transaction, apiResponse) {});

create

create(options, callback) returns Promise containing CreateSessionResponse

Create a session.

Parameter
options	Optional object See Database#createSession.
callback	Optional CreateSessionCallback Callback function.

Returns

Promise containing CreateSessionResponse 

Example

session.create(function(err, session, apiResponse) {
  if (err) {
    // Error handling omitted.
  }

  // Session created successfully.
});

//-
// If the callback is omitted, we'll return a Promise.
//-
session.create()
  .then(function(data) {
    const session = data[0];
    const apiResponse = data[1];

    // Session created successfully.
  });

delete

delete(callback) returns Promise containing BasicResponse

Delete a session.

Wrapper around v1.SpannerClient#deleteSession.

Parameter
callback	Optional BasicCallback Callback function.

See also

v1.SpannerClient#deleteSession

DeleteSession API Documentation

Returns

Promise containing BasicResponse 

Example

session.delete(function(err, apiResponse) {
  if (err) {
    // Error handling omitted.
  }

  // Session deleted successfully.
});

//-
// If the callback is omitted, we'll return a Promise.
//-
session.delete().then(function(data) {
  const apiResponse = data[0];
});

exists

exists(callback) returns Promise containing SessionExistsResponse

Check if a session exists.

Parameter
callback	Optional SessionExistsCallback Callback function.

Returns

Promise containing SessionExistsResponse 

Example

session.exists(function(err, exists) {});

//-
// If the callback is omitted, we'll return a Promise.
//-
session.exists().then(function(data) {
  const exists = data[0];
});

get

get(options, callback) returns Promise containing GetSessionResponse

Get a session if it exists.

You may optionally use this to "get or create" an object by providing an object with autoCreate set to true. Any extra configuration that is normally required for the create method must be contained within this object as well.

Parameter
options	Optional options Configuration object. Values in options have the following properties: Parameter autoCreate Optional boolean Automatically create the object if it does not exist.
callback	Optional GetSessionCallback Callback function.

Returns

Promise containing GetSessionResponse 

Example

session.get(function(err, session, apiResponse) {
  // `session.metadata` has been populated.
});

//-
// If the callback is omitted, we'll return a Promise.
//-
session.get().then(function(data) {
  const session = data[0];
  const apiResponse = data[0];
});

getMetadata

getMetadata(callback) returns Promise containing GetSessionMetadataResponse

Get the session's metadata.

Wrapper around v1.SpannerClient#getSession.

Parameter
callback	Optional GetSessionMetadataCallback Callback function.

See also

v1.SpannerClient#getSession

GetSession API Documentation

Returns

Promise containing GetSessionMetadataResponse 

Example

session.getMetadata(function(err, metadata, apiResponse) {});

//-
// If the callback is omitted, we'll return a Promise.
//-
session.getMetadata().then(function(data) {
  const metadata = data[0];
  const apiResponse = data[1];
});

keepAlive

keepAlive(callback) returns Promise containing BasicResponse

Ping the session with SELECT 1 to prevent it from expiring.

Parameter
callback	Optional BasicCallback Callback function.

Returns

Promise containing BasicResponse 

Example

session.keepAlive(function(err) {
  if (err) {
    // An error occurred while trying to keep this session alive.
  }
});

transaction

transaction(id) returns Transaction

Create a Transaction object.

Parameter
id	string The id of the transaction.

Throws

Error 

If an ID is not provided.

Returns

Transaction 

A Transaction object.

Example

const transaction = database.transaction('transaction-id');