db: add subject_id, subject_type columns to mod_actions.

The subject of the mod action is the post, user, or other object the modaction is for.

db/migrate/20220925045236_add_subject_to_mod_actions.rb

@@ -0,0 +1,9 @@
+class AddSubjectToModActions < ActiveRecord::Migration[7.0]
+  def change
+    add_column :mod_actions, :subject_type, :string, null: true
+    add_column :mod_actions, :subject_id, :integer, null: true
+
+    add_index :mod_actions, :subject_type
+    add_index :mod_actions, :subject_id
+  end
+end

db/structure.sql

@@ -993,7 +993,9 @@ CREATE TABLE public.mod_actions (
     description text NOT NULL,
     created_at timestamp without time zone NOT NULL,
     updated_at timestamp without time zone NOT NULL,
-    category integer NOT NULL
+    category integer NOT NULL,
+    subject_type character varying,
+    subject_id integer
 );
 
 
@@ -4396,6 +4398,20 @@ CREATE INDEX index_mod_actions_on_creator_id_and_created_at ON public.mod_action
 CREATE INDEX index_mod_actions_on_description ON public.mod_actions USING gin (description public.gin_trgm_ops);
 
 
+--
+-- Name: index_mod_actions_on_subject_id; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE INDEX index_mod_actions_on_subject_id ON public.mod_actions USING btree (subject_id);
+
+
+--
+-- Name: index_mod_actions_on_subject_type; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE INDEX index_mod_actions_on_subject_type ON public.mod_actions USING btree (subject_type);
+
+
 --
 -- Name: index_mod_actions_on_to_tsvector_pg_catalog_english_description; Type: INDEX; Schema: public; Owner: -
 --
@@ -6722,6 +6738,7 @@ INSERT INTO "schema_migrations" (version) VALUES
 ('20220921022408'),
 ('20220922014326'),
 ('20220923010905'),
-('20220924092056');
+('20220924092056'),
+('20220925045236');