migrations: add shade layers for old maps

.pre-commit-config.yaml

@@ -90,7 +90,7 @@ repos:
     rev: 23.7.0
     hooks:
       - id: black
-        language_version: python3.9.2
+        language_version: python3
   - repo: https://github.com/PyCQA/flake8
     rev: 6.0.0
     hooks:

backend/migrations/2023-08-08-200334_add_missing_shade_layers/down.sql

@@ -0,0 +1 @@
+-- This migration can not be undone!

backend/migrations/2023-08-08-200334_add_missing_shade_layers/up.sql

@@ -0,0 +1,17 @@
+INSERT INTO layers (map_id, type, name, is_alternative)
+SELECT
+    maps_without_shade_layer.id AS map_id,
+    'shade' AS type, -- noqa: RF04
+    'Shade Layer' AS name, -- noqa: RF04
+    false AS is_alternative
+FROM (
+    SELECT maps.id AS id
+    FROM maps
+
+    EXCEPT
+
+    SELECT maps.id
+    FROM maps
+    LEFT JOIN layers ON layers.map_id = maps.id
+    WHERE layers.type = 'shade'
+) AS maps_without_shade_layer;