Transaction

Transaction is a context manager that wraps one or more SQL operations in a single atomic unit: commits on success, rolls back on exception.

Nested with Transaction(model) blocks use PostgreSQL savepoints automatically — an exception in an inner block rolls back only that scope, leaving the outer transaction intact.

See Learn halfORM in half an hour for a full walkthrough.

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Transaction

Context manager for atomic database operations.

Wraps one or more SQL operations in a single transaction: commits on success, rolls back on exception. Transactions are per-thread and per-model instance.

Nested with Transaction(model) blocks use PostgreSQL savepoints automatically: an exception in an inner block rolls back only that inner block, leaving the outer transaction intact.

Parameters:

Name	Type	Description	Default
model	Model	the :class:~half_orm.model.Model instance whose connection should be used.	required

Example

Atomic insert of two related rows:

from half_orm.transaction import Transaction

with Transaction(blog):
    alice = Author(
        first_name='Alice', last_name='Martin',
        email='alice@example.com',
    ).ho_insert()
    Post(
        title='First post', content='Hello world',
        author_id=alice['id'],
    ).ho_insert()
# both rows are committed, or neither is

Nested transactions use savepoints:

with Transaction(blog):
    alice = Author(...).ho_insert()
    with Transaction(blog):          # savepoint
        Post(...).ho_insert()
        # exception here rolls back only the post, not Alice

New in version 0.18.0: nested Transaction blocks use savepoints.