feat: fix water elevation units to feet in materialized view and update related tests

alembic/versions/n7a8b9c0d1e2_fix_water_elevation_units_to_feet.py

@@ -0,0 +1,122 @@
+"""fix water elevation units to feet
+
+Revision ID: n7a8b9c0d1e2
+Revises: m6f7a8b9c0d1
+Create Date: 2026-03-10 11:10:00.000000
+"""
+
+from typing import Sequence, Union
+
+from alembic import op
+from sqlalchemy import inspect, text
+
+# revision identifiers, used by Alembic.
+revision: str = "n7a8b9c0d1e2"
+down_revision: Union[str, Sequence[str], None] = "m6f7a8b9c0d1"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+METERS_TO_FEET = 3.28084
+
+LATEST_LOCATION_CTE = """
+SELECT DISTINCT ON (lta.thing_id)
+    lta.thing_id,
+    lta.location_id,
+    lta.effective_start
+FROM location_thing_association AS lta
+WHERE lta.effective_end IS NULL
+ORDER BY lta.thing_id, lta.effective_start DESC
+""".strip()
+
+
+def _create_water_elevation_view() -> str:
+    return f"""
+        CREATE MATERIALIZED VIEW ogc_water_elevation_wells AS
+        WITH latest_location AS (
+{LATEST_LOCATION_CTE}
+        ),
+        ranked_obs AS (
+            SELECT
+                fe.thing_id,
+                o.id AS observation_id,
+                o.observation_datetime,
+                (o.value - COALESCE(o.measuring_point_height, 0))
+                    AS depth_to_water_below_ground_surface
+            FROM observation AS o
+            JOIN sample AS s ON s.id = o.sample_id
+            JOIN field_activity AS fa ON fa.id = s.field_activity_id
+            JOIN field_event AS fe ON fe.id = fa.field_event_id
+            JOIN thing AS t ON t.id = fe.thing_id
+            WHERE
+                t.thing_type = 'water well'
+                AND fa.activity_type = 'groundwater level'
+                AND o.value IS NOT NULL
+                AND o.observation_datetime IS NOT NULL
+        ),
+        latest_obs AS (
+            SELECT
+                ro.*,
+                ROW_NUMBER() OVER (
+                    PARTITION BY ro.thing_id
+                    ORDER BY ro.observation_datetime DESC, ro.observation_id DESC
+                ) AS rn
+            FROM ranked_obs AS ro
+        )
+        SELECT
+            t.id AS id,
+            t.name,
+            t.thing_type,
+            lo.observation_id,
+            lo.observation_datetime,
+            l.elevation,
+            lo.depth_to_water_below_ground_surface,
+            ((l.elevation * {METERS_TO_FEET}) - lo.depth_to_water_below_ground_surface)
+                AS water_elevation,
+            l.point
+        FROM latest_obs AS lo
+        JOIN thing AS t ON t.id = lo.thing_id
+        JOIN latest_location AS ll ON ll.thing_id = t.id
+        JOIN location AS l ON l.id = ll.location_id
+        WHERE lo.rn = 1
+    """
+
+
+def upgrade() -> None:
+    bind = op.get_bind()
+    inspector = inspect(bind)
+    existing_tables = set(inspector.get_table_names(schema="public"))
+    required_tables = {
+        "thing",
+        "location",
+        "location_thing_association",
+        "observation",
+        "sample",
+        "field_activity",
+        "field_event",
+    }
+
+    if not required_tables.issubset(existing_tables):
+        missing = sorted(t for t in required_tables if t not in existing_tables)
+        raise RuntimeError(
+            "Cannot create ogc_water_elevation_wells. Missing required tables: "
+            + ", ".join(missing)
+        )
+
+    op.execute(text("DROP MATERIALIZED VIEW IF EXISTS ogc_water_elevation_wells"))
+    op.execute(text(_create_water_elevation_view()))
+    op.execute(
+        text(
+            "COMMENT ON MATERIALIZED VIEW ogc_water_elevation_wells IS "
+            "'Latest water elevation per well in feet; computed as (elevation_m * 3.28084) - depth_to_water_below_ground_surface_ft.'"
+        )
+    )
+    op.execute(
+        text(
+            "CREATE UNIQUE INDEX ux_ogc_water_elevation_wells_id "
+            "ON ogc_water_elevation_wells (id)"
+        )
+    )
+
+
+def downgrade() -> None:
+    op.execute(text("DROP MATERIALIZED VIEW IF EXISTS ogc_water_elevation_wells"))

tests/test_ogc.py

@@ -344,7 +344,8 @@ def test_ogc_water_elevation_wells_computes_elevation_minus_depth_to_water(
 
         assert float(row.depth_to_water_below_ground_surface) == 5.0
         assert float(row.elevation) == 2464.9
-        assert abs(float(row.water_elevation) - 2459.9) < 1e-9
+        expected_water_elevation_ft = (2464.9 * 3.28084) - 5.0
+        assert abs(float(row.water_elevation) - expected_water_elevation_ft) < 1e-9
 
 
 def test_ogc_collections():