103 lines
3.2 KiB
Python
103 lines
3.2 KiB
Python
"""add temporal validity to categories
|
|
|
|
Revision ID: d9c6533f8a1b
|
|
Revises: 78ec55b9e1d1
|
|
Create Date: 2026-10-25 00:00:00.000000
|
|
|
|
"""
|
|
|
|
from collections.abc import Sequence
|
|
|
|
import sqlalchemy as sa
|
|
|
|
from alembic import op
|
|
|
|
# revision identifiers, used by Alembic.
|
|
revision: str = "d9c6533f8a1b"
|
|
down_revision: str | Sequence[str] | None = "78ec55b9e1d1"
|
|
branch_labels: str | Sequence[str] | None = None
|
|
depends_on: str | Sequence[str] | None = None
|
|
|
|
|
|
def upgrade() -> None:
|
|
with op.batch_alter_table("category") as batch_op:
|
|
batch_op.drop_constraint("uq_category_name_parent", type_="unique")
|
|
batch_op.add_column(
|
|
sa.Column(
|
|
"valid_from",
|
|
sa.DateTime(timezone=True),
|
|
nullable=True,
|
|
info={
|
|
"description": "UTC start of validity; NULL means valid since the indefinite past."
|
|
},
|
|
)
|
|
)
|
|
batch_op.add_column(
|
|
sa.Column(
|
|
"valid_to",
|
|
sa.DateTime(timezone=True),
|
|
nullable=True,
|
|
info={
|
|
"description": "UTC end of validity; NULL means the version is currently valid."
|
|
},
|
|
)
|
|
)
|
|
batch_op.add_column(
|
|
sa.Column(
|
|
"last_action",
|
|
sa.String(),
|
|
nullable=False,
|
|
server_default="created",
|
|
info={
|
|
"description": "Most recent lifecycle action recorded for this category version."
|
|
},
|
|
)
|
|
)
|
|
|
|
# Existing rows predate temporal tracking, so their start is unbounded.
|
|
op.execute("UPDATE category SET last_action = 'migrated'")
|
|
|
|
# Separate root and non-root indexes so NULL parent IDs are unique too.
|
|
op.create_index(
|
|
"uq_category_active_name_parent",
|
|
"category",
|
|
["name", "parent_id"],
|
|
unique=True,
|
|
sqlite_where=sa.text("valid_to IS NULL AND parent_id IS NOT NULL"),
|
|
postgresql_where=sa.text("valid_to IS NULL AND parent_id IS NOT NULL"),
|
|
)
|
|
op.create_index(
|
|
"uq_category_active_root_name",
|
|
"category",
|
|
["name"],
|
|
unique=True,
|
|
sqlite_where=sa.text("valid_to IS NULL AND parent_id IS NULL"),
|
|
postgresql_where=sa.text("valid_to IS NULL AND parent_id IS NULL"),
|
|
)
|
|
|
|
|
|
def downgrade() -> None:
|
|
bind = op.get_bind()
|
|
has_temporal_history = bind.execute(
|
|
sa.text(
|
|
"SELECT 1 FROM category "
|
|
"WHERE valid_from IS NOT NULL OR valid_to IS NOT NULL LIMIT 1"
|
|
)
|
|
).first()
|
|
if has_temporal_history:
|
|
raise RuntimeError(
|
|
"Cannot downgrade category validity while temporal history exists; "
|
|
"the downgrade would discard it."
|
|
)
|
|
|
|
op.drop_index("uq_category_active_root_name", table_name="category")
|
|
op.drop_index("uq_category_active_name_parent", table_name="category")
|
|
|
|
with op.batch_alter_table("category") as batch_op:
|
|
batch_op.drop_column("last_action")
|
|
batch_op.drop_column("valid_to")
|
|
batch_op.drop_column("valid_from")
|
|
batch_op.create_unique_constraint(
|
|
"uq_category_name_parent", ["name", "parent_id"]
|
|
)
|