Method: projects.beginTransaction

Begins a new transaction.

HTTP request

POST https://datastore.googleapis.com/v1beta3/projects/{projectId}:beginTransaction

The URL uses gRPC Transcoding syntax.

Path parameters

Parameters
projectId

string

Required. The ID of the project against which to make the request.

Request body

The request body contains data with the following structure:

JSON representation 
{
  "transactionOptions": {
    object (TransactionOptions)
  }
}
Fields
transactionOptions

object (TransactionOptions)

Options for a new transaction.

Response body

The response for Datastore.BeginTransaction.

If successful, the response body contains data with the following structure:

JSON representation 
{
  "transaction": string
}
Fields
transaction

string (bytes format)

The transaction identifier (always present).

A base64-encoded string.

Authorization scopes

Requires one of the following OAuth scopes:

  • https://www.googleapis.com/auth/datastore
  • https://www.googleapis.com/auth/cloud-platform

For more information, see the Authentication Overview.

TransactionOptions

Options for beginning a new transaction.

Transactions can be created explicitly with calls to Datastore.BeginTransaction or implicitly by setting ReadOptions.new_transaction in read requests.

JSON representation 
{

  // Union field mode can be only one of the following:
  "readWrite": {
    object (ReadWrite)
  },
  "readOnly": {
    object (ReadOnly)
  }
  // End of list of possible types for union field mode.
}
Fields
Union field mode. The mode of the transaction, indicating whether write operations are supported. mode can be only one of the following:
readWrite

object (ReadWrite)

The transaction should allow both reads and writes.
readOnly

object (ReadOnly)

The transaction should only allow reads.

ReadWrite

Options specific to read / write transactions.

JSON representation 
{
  "previousTransaction": string
}
Fields
previousTransaction

string (bytes format)

The transaction identifier of the transaction being retried.

A base64-encoded string.

ReadOnly

Options specific to read-only transactions.

JSON representation 
{
  "readTime": string
}
Fields
readTime

string (Timestamp format)

Reads entities at the given time.

This must be a microsecond precision timestamp within the past one hour, or if Point-in-Time Recovery is enabled, can additionally be a whole minute timestamp within the past 7 days.

Uses RFC 3339, where generated output will always be Z-normalized and uses 0, 3, 6 or 9 fractional digits. Offsets other than "Z" are also accepted.Examples: "2014-10-02T15:01:23Z", "2014-10-02T15:01:23.045123456Z" or "2014-10-02T15:01:23+05:30".