add: delete sensor on cascade measurements

Author: mosoriob

alembic/versions/778a9dbdeb5e_add_cascade_delete_to_measurements_.py

@@ -0,0 +1,49 @@
+"""add cascade delete to measurements.sensorid foreign key
+
+Revision ID: 778a9dbdeb5e
+Revises: add_unique_constraint_to_values
+Create Date: 2025-08-02 15:47:56.175249
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = '778a9dbdeb5e'
+down_revision: Union[str, None] = 'add_unique_constraint_to_values'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    # Drop the existing foreign key constraint
+    op.drop_constraint('measurements_sensorid_fkey', 'measurements', type_='foreignkey')
+    
+    # Add the new foreign key constraint with CASCADE delete
+    op.create_foreign_key(
+        'measurements_sensorid_fkey',
+        'measurements',
+        'sensors',
+        ['sensorid'],
+        ['sensorid'],
+        ondelete='CASCADE'
+    )
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    # Drop the CASCADE foreign key constraint
+    op.drop_constraint('measurements_sensorid_fkey', 'measurements', type_='foreignkey')
+    
+    # Recreate the original foreign key constraint without CASCADE
+    op.create_foreign_key(
+        'measurements_sensorid_fkey',
+        'measurements',
+        'sensors',
+        ['sensorid'],
+        ['sensorid']
+    )

app/db/models/measurement.py

@@ -12,7 +12,7 @@ class Measurement(Base):
     __tablename__ = "measurements"
 
     measurementid: Mapped[int] = mapped_column(primary_key=True, index=True)
-    sensorid: Mapped[int] = mapped_column(ForeignKey("sensors.sensorid"))
+    sensorid: Mapped[int] = mapped_column(ForeignKey("sensors.sensorid", ondelete="CASCADE"))
     stationid: Mapped[int] = mapped_column()
     collectiontime: Mapped[datetime] = mapped_column()
     measurementvalue: Mapped[float] = mapped_column()

app/db/repositories/sensor_repository.py

@@ -257,8 +257,9 @@ def get_sensors(
         return result, total_count
 
     def delete_sensor(self, sensor_id: int) -> bool:
-        db_sensor = self.get_sensor(sensor_id)
+        db_sensor = self.db.query(Sensor).filter(Sensor.sensorid == sensor_id).first()
         if db_sensor:
+            # Database CASCADE will automatically delete measurements and statistics
             self.db.delete(db_sensor)
             self.db.commit()
             return True