Manage field mapping in SQL declaratively

Simplify some of the OSM->OMT field value mappings using declarative syntax.

This approach is not for all cases, but in many it removes
the need of storing the same field in both the .yaml and .sql files.

TODO: support more complex AND/OR cases

layers/aerodrome_label/aerodrome_label.yaml

@@ -15,12 +15,23 @@ layer:
           [`aerodrome`](http://wiki.openstreetmap.org/wiki/Proposed_features/Aerodrome)
           and `aerodrome:type` tags.
       values:
-      - international
-      - public
-      - regional
-      - military
-      - private
-      - other
+        international:
+          aerodrome: 'international'
+          aerodrome_type: 'international'
+        public:
+          aerodrome: 'public'
+          aerodrome_type: ['%public%', 'civil']
+        regional:
+          aerodrome: 'regional'
+          aerodrome_type: 'regional'
+        military:
+          aerodrome: 'military'
+          aerodrome_type: '%military%'
+          military: 'airfield'
+        private:
+          aerodrome: 'private'
+          aerodrome_type: 'private'
+        other:
     iata: 3-character code issued by the IATA.
     icao: 4-letter code issued by the ICAO.
     ele: Elevation (`ele`) in meters.

layers/aerodrome_label/layer.sql

@@ -27,27 +27,7 @@ $$
     COALESCE(NULLIF(name_de, ''), name, name_en) AS name_de,
     tags,
     CASE
-      WHEN aerodrome = 'international'
-          OR aerodrome_type = 'international'
-        THEN 'international'
-      WHEN
-          aerodrome = 'public'
-          OR aerodrome_type LIKE '%public%'
-          OR aerodrome_type = 'civil'
-        THEN 'public'
-      WHEN
-          aerodrome = 'regional'
-          OR aerodrome_type = 'regional'
-        THEN 'regional'
-      WHEN
-          aerodrome = 'military'
-          OR aerodrome_type LIKE '%military%'
-          OR military = 'airfield'
-        THEN 'military'
-      WHEN
-          aerodrome = 'private'
-          OR aerodrome_type = 'private'
-        THEN 'private'
+      %%FIELD_MAPPING: class %%
       ELSE 'other'
     END AS class,
     NULLIF(iata, '') AS iata,

layers/landcover/landcover.sql

@@ -11,15 +11,7 @@
 
 CREATE OR REPLACE FUNCTION landcover_class(subclass VARCHAR) RETURNS TEXT AS $$
     SELECT CASE
-        WHEN subclass IN ('farmland', 'farm', 'orchard', 'vineyard', 'plant_nursery') THEN 'farmland'
-        WHEN subclass IN ('glacier', 'ice_shelf') THEN 'ice'
-        WHEN subclass IN ('wood', 'forest') THEN 'wood'
-        WHEN subclass IN ('bare_rock', 'scree') THEN 'rock'
-        WHEN subclass IN ('fell', 'grassland', 'heath', 'scrub', 'tundra', 'grass', 'meadow', 'allotments',
-                          'park', 'village_green', 'recreation_ground', 'garden', 'golf_course') THEN 'grass'
-        WHEN subclass IN ('wetland', 'bog', 'swamp', 'wet_meadow', 'marsh', 'reedbed',
-                          'saltern', 'tidalflat', 'saltmarsh', 'mangrove') THEN 'wetland'
-        WHEN subclass IN ('beach', 'sand', 'dune') THEN 'sand'
+        %%FIELD_MAPPING: class %%
         ELSE NULL
     END;
 $$ LANGUAGE SQL IMMUTABLE;

layers/landcover/landcover.yaml

@@ -10,12 +10,20 @@ layer:
       description: |
           Use the **class** to assign natural colors for **landcover**.
       values:
-      - farmland
-      - ice
-      - wood
-      - grass
-      - wetland
-      - sand
+        farmland:
+          subclass: ['farmland', 'farm', 'orchard', 'vineyard', 'plant_nursery']
+        ice:
+          subclass: ['glacier', 'ice_shelf']
+        wood:
+          subclass: ['wood', 'forest']
+        rock:
+          subclass: ['bare_rock', 'scree']
+        grass:
+          subclass: ['fell', 'grassland', 'heath', 'scrub', 'tundra', 'grass', 'meadow', 'allotments', 'park', 'village_green', 'recreation_ground', 'garden', 'golf_course']
+        wetland:
+          subclass: ['wetland', 'bog', 'swamp', 'wet_meadow', 'marsh', 'reedbed', 'saltern', 'tidalflat', 'saltmarsh', 'mangrove']
+        sand:
+          subclass: ['beach', 'sand', 'dune']
     subclass:
       description: |
           Use **subclass** to do more precise styling.

layers/poi/class.sql

@@ -30,39 +30,10 @@ $$ LANGUAGE SQL IMMUTABLE;
 CREATE OR REPLACE FUNCTION poi_class(subclass TEXT, mapping_key TEXT)
 RETURNS TEXT AS $$
     SELECT CASE
-        WHEN subclass IN ('accessories','antiques','beauty','bed','boutique','camera','carpet','charity','chemist','coffee','computer','convenience','copyshop','cosmetics','garden_centre','doityourself','erotic','electronics','fabric','florist','frozen_food','furniture','video_games','video','general','gift','hardware','hearing_aids','hifi','ice_cream','interior_decoration','jewelry','kiosk','lamps','mall','massage','motorcycle','mobile_phone','newsagent','optician','outdoor','perfumery','perfume','pet','photo','second_hand','shoes','sports','stationery','tailor','tattoo','ticket','tobacco','toys','travel_agency','watches','weapons','wholesale') THEN 'shop'
-        WHEN subclass IN ('townhall','public_building','courthouse','community_centre') THEN 'town_hall'
-        WHEN subclass IN ('golf','golf_course','miniature_golf') THEN 'golf'
-        WHEN subclass IN ('fast_food','food_court') THEN 'fast_food'
-        WHEN subclass IN ('park','bbq') THEN 'park'
-        WHEN subclass IN ('bus_stop','bus_station') THEN 'bus'
-        WHEN (subclass='station' AND mapping_key = 'railway') OR subclass IN ('halt', 'tram_stop', 'subway') THEN 'railway'
-        WHEN (subclass='station' AND mapping_key = 'aerialway') THEN 'aerialway'
-        WHEN subclass IN ('subway_entrance','train_station_entrance') THEN 'entrance'
-        WHEN subclass IN ('camp_site','caravan_site') THEN 'campsite'
-        WHEN subclass IN ('laundry','dry_cleaning') THEN 'laundry'
-        WHEN subclass IN ('supermarket','deli','delicatessen','department_store','greengrocer','marketplace') THEN 'grocery'
-        WHEN subclass IN ('books','library') THEN 'library'
-        WHEN subclass IN ('university','college') THEN 'college'
-        WHEN subclass IN ('hotel','motel','bed_and_breakfast','guest_house','hostel','chalet','alpine_hut','dormitory') THEN 'lodging'
-        WHEN subclass IN ('chocolate','confectionery') THEN 'ice_cream'
-        WHEN subclass IN ('post_box','post_office') THEN 'post'
-        WHEN subclass IN ('cafe') THEN 'cafe'
-        WHEN subclass IN ('school','kindergarten') THEN 'school'
-        WHEN subclass IN ('alcohol','beverages','wine') THEN 'alcohol_shop'
-        WHEN subclass IN ('bar','nightclub') THEN 'bar'
-        WHEN subclass IN ('marina','dock') THEN 'harbor'
-        WHEN subclass IN ('car','car_repair','taxi') THEN 'car'
-        WHEN subclass IN ('hospital','nursing_home', 'clinic') THEN 'hospital'
-        WHEN subclass IN ('grave_yard','cemetery') THEN 'cemetery'
-        WHEN subclass IN ('attraction','viewpoint') THEN 'attraction'
-        WHEN subclass IN ('biergarten','pub') THEN 'beer'
-        WHEN subclass IN ('music','musical_instrument') THEN 'music'
-        WHEN subclass IN ('american_football','stadium','soccer') THEN 'stadium'
-        WHEN subclass IN ('art','artwork','gallery','arts_centre') THEN 'art_gallery'
-        WHEN subclass IN ('bag','clothes') THEN 'clothing_store'
-        WHEN subclass IN ('swimming_area','swimming') THEN 'swimming'
-        WHEN subclass IN ('castle','ruins') THEN 'castle'
+        %%FIELD_MAPPING: class %%
+        WHEN (subclass = 'station' AND mapping_key = 'railway')
+          OR (subclass IN ('halt', 'tram_stop', 'subway')) THEN 'railway'
+        WHEN (subclass = 'station' AND mapping_key = 'aerialway') THEN 'aerialway'
         ELSE subclass
     END;
 $$ LANGUAGE SQL IMMUTABLE;

layers/poi/poi.yaml

@@ -9,11 +9,84 @@ layer:
     name: The OSM [`name`](http://wiki.openstreetmap.org/wiki/Key:name) value of the POI.
     name_en: English name `name:en` if available, otherwise `name`.
     name_de: German name `name:de` if available, otherwise `name` or `name:en`.
-    class: |
+    class:
+      description: |
         More general classes of POIs. If there is no more general `class` for the `subclass`
         this field will contain the same value as `subclass`.
         But for example for schools you only need to style the class `school` to filter the subclasses `school`
         and `kindergarten`. Or use the class `shop` to style all shops.
+      values:
+        shop:
+          subclass: ['accessories', 'antiques', 'beauty', 'bed', 'boutique', 'camera', 'carpet', 'charity', 'chemist',
+                     'coffee', 'computer', 'convenience', 'copyshop', 'cosmetics', 'garden_centre', 'doityourself',
+                     'erotic', 'electronics', 'fabric', 'florist', 'frozen_food', 'furniture', 'video_games', 'video',
+                     'general', 'gift', 'hardware', 'hearing_aids', 'hifi', 'ice_cream', 'interior_decoration',
+                     'jewelry', 'kiosk', 'lamps', 'mall', 'massage', 'motorcycle', 'mobile_phone', 'newsagent',
+                     'optician', 'outdoor', 'perfumery', 'perfume', 'pet', 'photo', 'second_hand', 'shoes', 'sports',
+                     'stationery', 'tailor', 'tattoo', 'ticket', 'tobacco', 'toys', 'travel_agency', 'watches',
+                     'weapons', 'wholesale']
+        town_hall:
+          subclass: ['townhall', 'public_building', 'courthouse', 'community_centre']
+        golf:
+          subclass: ['golf', 'golf_course', 'miniature_golf']
+        fast_food:
+          subclass: ['fast_food', 'food_court']
+        park:
+          subclass: ['park', 'bbq']
+        bus:
+          subclass: ['bus_stop', 'bus_station']
+        railway:
+        aerialway:
+        entrance:
+          subclass: ['subway_entrance', 'train_station_entrance']
+        campsite:
+          subclass: ['camp_site', 'caravan_site']
+        laundry:
+          subclass: ['laundry', 'dry_cleaning']
+        grocery:
+          subclass: ['supermarket', 'deli', 'delicatessen', 'department_store', 'greengrocer', 'marketplace']
+        library:
+          subclass: ['books', 'library']
+        college:
+          subclass: ['university', 'college']
+        lodging:
+          subclass: ['hotel', 'motel', 'bed_and_breakfast', 'guest_house', 'hostel', 'chalet', 'alpine_hut', 'dormitory']
+        ice_cream:
+          subclass: ['chocolate', 'confectionery']
+        post:
+          subclass: ['post_box', 'post_office']
+        cafe:
+          subclass: ['cafe']
+        school:
+          subclass: ['school', 'kindergarten']
+        alcohol_shop:
+          subclass: ['alcohol', 'beverages', 'wine']
+        bar:
+          subclass: ['bar', 'nightclub']
+        harbor:
+          subclass: ['marina', 'dock']
+        car:
+          subclass: ['car', 'car_repair', 'taxi']
+        hospital:
+          subclass: ['hospital', 'nursing_home', 'clinic']
+        cemetery:
+          subclass: ['grave_yard', 'cemetery']
+        attraction:
+          subclass: ['attraction', 'viewpoint']
+        beer:
+          subclass: ['biergarten', 'pub']
+        music:
+          subclass: ['music', 'musical_instrument']
+        stadium:
+          subclass: ['american_football', 'stadium', 'soccer']
+        art_gallery:
+          subclass: ['art', 'artwork', 'gallery', 'arts_centre']
+        clothing_store:
+          subclass: ['bag', 'clothes']
+        swimming:
+          subclass: ['swimming_area', 'swimming']
+        castle:
+          subclass: ['castle', 'ruins']
     subclass:
       description: |
           Original value of either the

layers/transportation/class.sql

@@ -11,23 +11,19 @@ $$ LANGUAGE SQL IMMUTABLE STRICT;
 -- https://github.com/ClearTables/ClearTables/blob/master/transportation.lua
 CREATE OR REPLACE FUNCTION highway_class(highway TEXT, public_transport TEXT, construction TEXT) RETURNS TEXT AS $$
     SELECT CASE
-        WHEN highway IN ('motorway', 'motorway_link') THEN 'motorway'
-        WHEN highway IN ('trunk', 'trunk_link') THEN 'trunk'
-        WHEN highway IN ('primary', 'primary_link') THEN 'primary'
-        WHEN highway IN ('secondary', 'secondary_link') THEN 'secondary'
-        WHEN highway IN ('tertiary', 'tertiary_link') THEN 'tertiary'
-        WHEN highway IN ('unclassified', 'residential', 'living_street', 'road') THEN 'minor'
-        WHEN highway IN ('pedestrian', 'path', 'footway', 'cycleway', 'steps', 'bridleway', 'corridor') OR public_transport IN ('platform') THEN 'path'
-        WHEN highway IN ('service', 'track', 'raceway') THEN highway
+        %%FIELD_MAPPING: class %%
         WHEN highway = 'construction' THEN CASE
           WHEN construction IN ('motorway', 'motorway_link') THEN 'motorway_construction'
           WHEN construction IN ('trunk', 'trunk_link') THEN 'trunk_construction'
           WHEN construction IN ('primary', 'primary_link') THEN 'primary_construction'
           WHEN construction IN ('secondary', 'secondary_link') THEN 'secondary_construction'
           WHEN construction IN ('tertiary', 'tertiary_link') THEN 'tertiary_construction'
-          WHEN construction = '' OR construction IN ('unclassified', 'residential', 'living_street', 'road') THEN 'minor_construction'
-          WHEN construction IN ('pedestrian', 'path', 'footway', 'cycleway', 'steps', 'bridleway', 'corridor') OR public_transport IN ('platform') THEN 'path_construction'
-          WHEN construction IN ('service', 'track', 'raceway') THEN CONCAT(highway, '_construction')
+          WHEN construction IN ('', 'unclassified', 'residential', 'living_street', 'road') THEN 'minor_construction'
+          WHEN construction IN ('pedestrian', 'path', 'footway', 'cycleway', 'steps', 'bridleway', 'corridor')
+              OR public_transport = 'platform' THEN 'path_construction'
+          WHEN construction = 'service' THEN 'service_construction'
+          WHEN construction = 'track' THEN 'track_construction'
+          WHEN construction = 'raceway' THEN 'raceway_construction'
           ELSE NULL
         END
         ELSE NULL

layers/transportation/transportation.yaml

@@ -24,33 +24,37 @@ layer:
           shipping ways), or
           [`man_made`](http://wiki.openstreetmap.org/wiki/Key:route).
       values:
-      - motorway
-      - trunk
-      - primary
-      - secondary
-      - tertiary
-      - minor
-      - service
-      - track
-      - path
-      - raceway
-      - motorway_construction
-      - trunk_construction
-      - primary_construction
-      - secondary_construction
-      - tertiary_construction
-      - minor_construction
-      - service_construction
-      - track_construction
-      - path_construction
-      - raceway_construction
-      - rail
-      - transit
-      - cable_car
-      - gondola
-      - ferry
-      - bridge
-      - pier
+        motorway:
+          highway: ['motorway', 'motorway_link']
+        trunk:
+          highway: ['trunk', 'trunk_link']
+        primary:
+          highway: ['primary', 'primary_link']
+        secondary:
+          highway: ['secondary', 'secondary_link']
+        tertiary:
+          highway: ['tertiary', 'tertiary_link']
+        minor:
+          highway: ['unclassified', 'residential', 'living_street', 'road']
+        path:
+          highway: ['pedestrian', 'path', 'footway', 'cycleway', 'steps', 'bridleway', 'corridor']
+          public_transport: 'platform'
+        service:
+          highway: service
+        track:
+          highway: track
+        raceway:
+          highway: raceway
+        motorway_construction:
+        trunk_construction:
+        primary_construction:
+        secondary_construction:
+        tertiary_construction:
+        minor_construction:
+        path_construction:
+        service_construction:
+        track_construction:
+        raceway_construction:
     subclass:
       description: |
           Distinguish more specific classes of railway and path:

layers/water/water.sql

@@ -1,8 +1,6 @@
 CREATE OR REPLACE FUNCTION water_class(waterway TEXT) RETURNS TEXT AS $$
     SELECT CASE
-           WHEN waterway='' THEN 'lake'
-           WHEN waterway='lake' THEN 'lake'
-           WHEN waterway='dock' THEN 'dock'
+           %%FIELD_MAPPING: class %%
            ELSE 'river'
    END;
 $$ LANGUAGE SQL IMMUTABLE;

layers/water/water.yaml

@@ -14,9 +14,12 @@ layer:
           All water polygons from [OpenStreetMapData](http://osmdata.openstreetmap.de/) have the class `ocean`.
           Water bodies are classified as `lake` or `river` for water bodies with the [`waterway`](http://wiki.openstreetmap.org/wiki/Key:waterway) tag.
       values:
-      - ocean
-      - lake
-      - river
+        lake:
+          waterway: ['', 'lake']
+        dock:
+          waterway: 'dock'
+        river:
+        ocean:
     intermittent:
       description: |
         Mark with `1` if it is an [intermittent](http://wiki.openstreetmap.org/wiki/Key:intermittent) water polygon.