crandas.transactions

Transaction implementation.

exception crandas.transactions.DirectlyAccessingDeferredObjectError

Bases: Exception

Exception when accessing a deferred object outside a transaction

Operations performed inside a transaction return “deferred” objects (e.g., a CDataFrame that is an instance of crandas.command.Deferred). Such deferred objects can be used inside the transaction but not outside it. When the transaction has completed, the resulting object is stored as the .result field of the deferred object. Outside of the object, this result field should be used. If the deferred object is used instead, this exception is raised.

class crandas.transactions.Transaction(*, session=None, dummy_for=False, name=None, add_nonce=False, _keep=None, **execute_args)

Bases: object

Transaction context manager

When used as a context manager (i.e., in a with Transaction(): block), causes all commands in the context to be executed at the server as a single init. See transactions.

crandas.transactions.show_transaction_graph(t, outfile)

Generates a transaction graph

Parameters:

• t (Transaction) – the Transaction to be graphed

• outfile (str) – name of the output file