Datastore/src/Operation.php
public function beginTransaction($transactionOptions, array $options = [])
    {
        $res = $this->connection->beginTransaction([
            'projectId' => $this->projectId,
            'transactionOptions' => $transactionOptions
        ] + $options);

        return $res['transaction'];
    }
public function beginTransaction($transactionOptions, array $options = [])
    {
        $res = $this->connection->beginTransaction([
            'projectId' => $this->projectId,
            'transactionOptions' => $transactionOptions
        ] + $options);

        return $res['transaction'];
    }
public function beginTransaction ( $ transactionOptions , array $ options = [ ] ) { $ res = $ this -> connection -> beginTransaction ( [ 'projectId' => $ this -> projectId , 'transactionOptions' => $ transactionOptions ] + $ options ) ; return $ res [ 'transaction' ] ; }
Begin a Datastore Transaction.

@param array $transactionOptions
[Transaction Options](https://cloud.google.com/datastore/docs/reference/data/rest/v1/projects/beginTransaction#TransactionOptions)
@param array $options Configuration options.
@return string
Begin a Datastore Transaction .