Run each migration in a separate transaction

[pythonweb2]

Is there a way to run each migration in a seperate transaction? I am using Postgres, and I am trying to set up something like this with auto-migrations.

script.py.mako

"""${message}

Revision ID: ${up_revision}
Revises: ${down_revision | comma,n}
Create Date: ${create_date}

"""
from alembic import op
import sqlalchemy as sa
${imports if imports else ""}

# revision identifiers, used by Alembic.
revision = ${repr(up_revision)}
down_revision = ${repr(down_revision)}
branch_labels = ${repr(branch_labels)}
depends_on = ${repr(depends_on)}


def upgrade():
    with context.begin_transaction():
        ${upgrades if upgrades else "pass"}


def downgrade():
    with context.begin_transaction():
        ${downgrades if downgrades else "pass"}

env.py

def run_migrations_online():
    """Run migrations in 'online' mode.

    In this scenario we need to create an Engine
    and associate a connection with the context.

    """
    connectable = engine_from_config(
        config.get_section(config.config_ini_section),
        prefix="sqlalchemy.",
        poolclass=pool.NullPool,
    )

    with connectable.connect() as connection:
        context.configure(connection=connection, target_metadata=target_metadata)
        # >>>> removed the transaction block here
        context.run_migrations()

A couple things. This feels a bit hacky, and I am just wondering if there is a better way to do it. Also, the mako template doesn't seem to add extra whitespace inside of the context manager.

example revision

def upgrade():
    with context.begin_transaction():
        # ### commands auto generated by Alembic - please adjust! ###
    op.create_table('transaction',
    sa.Column('id', sa.Integer(), nullable=False),
    sa.Column('amount', sa.Numeric(), nullable=True),
    sa.PrimaryKeyConstraint('id', name=op.f('pk_transaction'))
    )
    # ### end Alembic commands ###


def downgrade():
    with context.begin_transaction():
        # ### commands auto generated by Alembic - please adjust! ###
    op.drop_table('transaction')
    # ### end Alembic commands ###

[CaselIT]

hi,
Is using transaction_per_migration not an option?

[pythonweb2]

Didn't know this existed, thank you!

[zzzeek]

Is there a way to run each migration in a seperate transaction? I am using Postgres, and I am trying to set up something like this with auto-migrations.

absolutely, you can set transaction_per_migration for this.

A couple things. This feels a bit hacky, and I am just wondering if there is a better way to do it. Also, the mako template doesn't seem to add extra whitespace inside of the context manager.

Right...indentation is not part of what it renders, if you wanted to do that you'd break it into separate methods.

[pythonweb2]

Awesome, I shouldn't need the extra white space with the transaction_per_migration parameter. Thanks so much for the quick response!