Database upgrade 16: fix event edits.

Fixes #198.

etc/db/upgrades/upgrade16-v0.3.3-fix-event-log-edit.sql

@@ -0,0 +1,169 @@
+-- Fix not being able to edit a time-based event.
+--
+-- New schema version: 0.3.3
+--
+-- ATTENTION:
+--
+-- ENSURE YOU HAVE BACKED UP THE DATABASE BEFORE RUNNING THIS SCRIPT.
+--
+--
+-- NOTE: This upgrade affects all schemas in the database.
+-- NOTE: Each application starts a transaction, which must be committed
+-- or rolled back.
+--
+-- The event_log_update() function that gets called when trying to update
+-- the event_log view will not work if the caller does provide a timestamp
+-- or sequence + point in the list of fields to be updated. See:
+-- https://gitlab.com/wgp/dougal/software/-/issues/198
+--
+-- This fixes the problem by liberally using COALESCE() to merge the OLD
+-- and NEW records.
+--
+-- To apply, run as the dougal user:
+--
+-- psql <<EOF
+-- \i $THIS_FILE
+-- COMMIT;
+-- EOF
+--
+-- NOTE: It can be applied multiple times without ill effect.
+--
+
+BEGIN;
+
+CREATE OR REPLACE PROCEDURE show_notice (notice text) AS $$
+BEGIN
+	RAISE NOTICE '%', notice;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE OR REPLACE PROCEDURE pg_temp.upgrade_survey_schema (schema_name text) AS $$
+BEGIN
+
+	RAISE NOTICE 'Updating schema %', schema_name;
+	-- We need to set the search path because some of the trigger
+	-- functions reference other tables in survey schemas assuming
+	-- they are in the search path.
+	EXECUTE format('SET search_path TO %I,public', schema_name);
+
+	CREATE OR REPLACE FUNCTION event_log_update() RETURNS trigger
+	LANGUAGE plpgsql
+	AS $inner$
+	BEGIN
+		IF (TG_OP = 'INSERT') THEN
+
+			-- Complete the tstamp if possible
+			IF NEW.sequence IS NOT NULL AND NEW.point IS NOT NULL AND NEW.tstamp IS NULL THEN
+				SELECT COALESCE(
+					tstamp_from_sequence_shot(NEW.sequence, NEW.point),
+					tstamp_interpolate(NEW.sequence, NEW.point)
+				)
+				INTO NEW.tstamp;
+			END IF;
+
+			-- Any id that is provided will be ignored. The generated
+			-- id will match uid.
+			INSERT INTO event_log_full
+				(tstamp, sequence, point, remarks, labels, meta)
+			VALUES (NEW.tstamp, NEW.sequence, NEW.point, NEW.remarks, NEW.labels, NEW.meta);
+
+			RETURN NEW;
+
+		ELSIF (TG_OP = 'UPDATE') THEN
+			-- Set end of validity and create a new entry with id
+			-- matching that of the old entry.
+
+			-- NOTE: Do not allow updating an event that has meta.readonly = true
+			IF EXISTS
+				(SELECT *
+				FROM event_log_full
+				WHERE id = OLD.id AND (meta->>'readonly')::boolean IS TRUE)
+			THEN
+				RAISE check_violation USING MESSAGE = 'Cannot modify read-only entry';
+				RETURN NULL;
+			END IF;
+
+			-- If the sequence / point has changed, and no new tstamp is provided, get one
+			IF NEW.sequence <> OLD.sequence OR NEW.point <> OLD.point
+				AND NEW.sequence IS NOT NULL AND NEW.point IS NOT NULL
+				AND NEW.tstamp IS NULL OR NEW.tstamp = OLD.tstamp THEN
+				SELECT COALESCE(
+					tstamp_from_sequence_shot(NEW.sequence, NEW.point),
+					tstamp_interpolate(NEW.sequence, NEW.point)
+				)
+				INTO NEW.tstamp;
+			END IF;
+
+			UPDATE event_log_full
+			SET validity = tstzrange(lower(validity), current_timestamp)
+			WHERE validity @> current_timestamp AND id = OLD.id;
+
+			-- Any attempt to modify id will be ignored.
+			INSERT INTO event_log_full
+				(id, tstamp, sequence, point, remarks, labels, meta)
+			VALUES (
+				OLD.id,
+				COALESCE(NEW.tstamp, OLD.tstamp),
+				COALESCE(NEW.sequence, OLD.sequence),
+				COALESCE(NEW.point, OLD.point),
+				COALESCE(NEW.remarks, OLD.remarks),
+				COALESCE(NEW.labels, OLD.labels),
+				COALESCE(NEW.meta, OLD.meta)
+			);
+
+			RETURN NEW;
+
+		ELSIF (TG_OP = 'DELETE') THEN
+			-- Set end of validity.
+
+			-- NOTE: We *do* allow deleting an event that has meta.readonly = true
+			-- This could be of interest if for instance we wanted to keep the history
+			-- of QC results for a point, provided that the QC routines write to
+			-- event_log and not event_log_full
+			UPDATE event_log_full
+			SET validity = tstzrange(lower(validity), current_timestamp)
+			WHERE validity @> current_timestamp AND id = OLD.id;
+
+			RETURN NULL;
+		END IF;
+	END;
+	$inner$;
+
+	CREATE OR REPLACE TRIGGER event_log_tg INSTEAD OF INSERT OR DELETE OR UPDATE ON event_log FOR EACH ROW EXECUTE FUNCTION event_log_update();
+
+
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE OR REPLACE PROCEDURE pg_temp.upgrade_16 () AS $$
+DECLARE
+	row RECORD;
+BEGIN
+	FOR row IN
+		SELECT schema_name FROM information_schema.schemata
+		WHERE schema_name LIKE 'survey_%'
+		ORDER BY schema_name
+	LOOP
+		CALL pg_temp.upgrade_survey_schema(row.schema_name);
+	END LOOP;
+END;
+$$ LANGUAGE plpgsql;
+
+CALL pg_temp.upgrade_16();
+
+CALL show_notice('Cleaning up');
+DROP PROCEDURE pg_temp.upgrade_survey_schema (schema_name text);
+DROP PROCEDURE pg_temp.upgrade_16 ();
+
+CALL show_notice('Updating db_schema version');
+INSERT INTO public.info VALUES ('version', '{"db_schema": "0.3.3"}')
+ON CONFLICT (key) DO UPDATE
+	SET value = public.info.value || '{"db_schema": "0.3.3"}' WHERE public.info.key = 'version';
+
+
+CALL show_notice('All done. You may now run "COMMIT;" to persist the changes');
+DROP PROCEDURE show_notice (notice text);
+
+--
+--NOTE Run `COMMIT;` now if all went well
+--