Django1.6，事务是否适用于原始 SQL？

Question

来自官方文档的示例

from django.db import connection

def my_custom_sql(self):
    cursor = connection.cursor()

    cursor.execute("UPDATE bar SET foo = 1 WHERE baz = %s", [self.baz])

    cursor.execute("SELECT foo FROM bar WHERE baz = %s", [self.baz])
    row = cursor.fetchone()

    return row

如果更新会影响选择，例如

cursor.execute("UPDATE bar SET foo = foo + 1 WHERE baz = %s", [self.baz])
cursor.execute("SELECT foo FROM bar WHERE baz = %s", [self.baz])

事务是否适用于原始 SQL，就像这个 snap 代码一样有效？

from django.db import connection, transaction

def my_custom_sql(self):
    try:
        with transaction.atomic():
            cursor = connection.cursor()
            cursor.execute("UPDATE bar SET foo = foo + 1 WHERE baz = %s", [self.baz])
            cursor.execute("SELECT foo FROM bar WHERE baz = %s", [self.baz])
            row = cursor.fetchone()
            return row
    except IntegrityError:
        transaction.rollback()

或者对于第一个代码，begin cursor已经开始一个事务？

Answer 1

我只能看到 self.db.validate_no_broken_transaction() here 的健全性检查：

def execute(self, sql, params=None):
    self.db.validate_no_broken_transaction()
    self.db.set_dirty()
    with self.db.wrap_database_errors:
        if params is None:
            return self.cursor.execute(sql)
        else:
            return self.cursor.execute(sql, params)

所以答案是否定的，游标默认情况下不会将原始 SQL 包装在事务中。

更新：

如果您需要交易和ATOMIC_REQUESTS = False，您可以使用transaction.atomic()，如decorator or context manager。

注意： django.db.connection 仅用于向后通信。你应该使用django.db.connections['default'] 甚至更好

from django.db import DEFAULT_DB_ALIAS

def get_connection(using=None):
    """
    Get a database connection by name, or the default database connection
    if no name is provided.
    """
    if using is None:
        using = DEFAULT_DB_ALIAS
    return connections[using]

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