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conference-room-booking-system/backend/migrations/versions/0006_make_bookings_tz_aware.py
T
2025-08-29 14:57:52 -04:00

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Python

"""Make bookings.start_time and bookings.end_time timezone-aware (TIMESTAMP WITH TIME ZONE)
Revision ID: 0006_make_bookings_tz_aware
Revises: 0005_adding_title_to_bookings
Create Date: 2025-08-29
"""
from typing import Sequence
from typing import Union
import sqlalchemy as sa
from alembic import op
# revision identifiers, used by Alembic.
revision: str = "0006"
down_revision: Union[str, Sequence[str], None] = "0005"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None
def upgrade() -> None:
"""Upgrade schema to use timezone-aware datetimes for bookings."""
# Drop exclusion constraint and check constraint
op.execute("ALTER TABLE bookings DROP CONSTRAINT IF EXISTS bookings_no_overlap;")
op.drop_constraint("ck_bookings_start_before_end", "bookings", type_="check")
# Alter columns to TIMESTAMP WITH TIME ZONE
op.alter_column(
"bookings",
"start_time",
type_=sa.TIMESTAMP(timezone=True),
existing_type=sa.TIMESTAMP(timezone=False),
postgresql_using=None,
)
op.alter_column(
"bookings",
"end_time",
type_=sa.TIMESTAMP(timezone=True),
existing_type=sa.TIMESTAMP(timezone=False),
postgresql_using=None,
)
# Re-add check constraint
op.create_check_constraint(
"ck_bookings_start_before_end", "bookings", "start_time < end_time"
)
# Re-add exclusion constraint for overlap prevention
op.execute(
"""
ALTER TABLE bookings
ADD CONSTRAINT bookings_no_overlap
EXCLUDE USING gist (
room_id WITH =,
tstzrange(start_time, end_time) WITH &&
);
"""
)
def downgrade() -> None:
"""Downgrade schema to use naive datetimes for bookings."""
op.execute("ALTER TABLE bookings DROP CONSTRAINT IF EXISTS bookings_no_overlap;")
op.drop_constraint("ck_bookings_start_before_end", "bookings", type_="check")
op.alter_column(
"bookings",
"start_time",
type_=sa.TIMESTAMP(timezone=False),
existing_type=sa.TIMESTAMP(timezone=True),
postgresql_using=None,
)
op.alter_column(
"bookings",
"end_time",
type_=sa.TIMESTAMP(timezone=False),
existing_type=sa.TIMESTAMP(timezone=True),
postgresql_using=None,
)
op.create_check_constraint(
"ck_bookings_start_before_end", "bookings", "start_time < end_time"
)
op.execute(
"""
ALTER TABLE bookings
ADD CONSTRAINT bookings_no_overlap
EXCLUDE USING gist (
room_id WITH =,
tsrange(start_time, end_time) WITH &&
);
"""
)