Jul 27 - Update code for scheduled tasks 2

migrations/versions/phase44_scheduled_end_date.py

@@ -0,0 +1,56 @@
+"""phase44 — scheduled inspection end date
+
+Adds `end_date` to `scheduled_inspections`:
+
+    end_date DATE NULL   -- last date this schedule may produce an occurrence
+
+Separates the two ideas that `next_due_date` was carrying at once. `next_due_date`
+is *mutable state* — ScheduledInspection.fulfill() rewrites it after every
+completed inspection — whereas `end_date` is a *fixed boundary* set by the
+manager and never touched by the app. NULL means "repeat indefinitely", which is
+the behaviour every existing row has today, so no backfill and no schedule
+changes cadence on deploy.
+
+Only meaningful for recurring schedules; the create/edit routes force it to NULL
+when frequency == 'once' (a one-time schedule already ends by deactivating on
+completion).
+
+Uses an INFORMATION_SCHEMA column-existence check — safe to re-run.
+Additive only: no existing column is renamed, retyped or dropped. In particular
+`next_due_date` keeps its name and its index — it is the API payload key the
+iPad decodes and is used by the reminder cron.
+"""
+
+revision      = 'phase44_sched_end_date'
+down_revision = 'phase43_sched_recurrence'
+branch_labels = None
+depends_on    = None
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def _column_exists(conn, table, column):
+    result = conn.execute(sa.text(
+        "SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS "
+        "WHERE TABLE_SCHEMA = DATABASE() "
+        "AND TABLE_NAME = :t AND COLUMN_NAME = :c"
+    ), {"t": table, "c": column})
+    return result.scalar() > 0
+
+
+def upgrade():
+    bind = op.get_bind()
+    if not _column_exists(bind, 'scheduled_inspections', 'end_date'):
+        op.execute(sa.text(
+            "ALTER TABLE scheduled_inspections "
+            "ADD COLUMN end_date DATE NULL AFTER next_due_date"
+        ))
+
+
+def downgrade():
+    bind = op.get_bind()
+    if _column_exists(bind, 'scheduled_inspections', 'end_date'):
+        op.execute(sa.text(
+            "ALTER TABLE scheduled_inspections DROP COLUMN end_date"
+        ))