Add option to create and index unique id columns on all tables

They are useful for instance if you want to be able to edit the data in
QGIS.

Author: joto

config/shortbread_gen.lua

@@ -13,6 +13,10 @@ themepark.debug = false
 -- Add JSONB column `tags` with original OSM tags in debug mode
 themepark:set_option('tags', 'all_tags')
 
+-- Set this to add a column 'id' with unique IDs (and corresponding unique
+-- index). This is needed for instance when you want to edit the data in QGIS.
+--themepark:set_option('unique_id', 'id')
+
 -- ---------------------------------------------------------------------------
 
 -- themepark:add_topic('core/name-single', { column = 'name' })

lua/themepark.lua

@@ -282,6 +282,19 @@ function themepark:add_table(data)
         })
     end
 
+    if themepark.options.unique_id then
+        table.insert(data.columns, {
+            column = themepark.options.unique_id,
+            sql_type = 'bigserial',
+            create_only = true
+        })
+        table.insert(data.indexes, {
+            column = themepark.options.unique_id,
+            unique = true,
+            method = 'btree'
+        })
+    end
+
     if data.geom then
         if type(data.geom) == 'string' then
             data.geom_type = data.geom