artist urls: add artist, url_matches search params to /artist_urls.

app/models/application_record.rb

@@ -5,6 +5,20 @@ class ApplicationRecord < ActiveRecord::Base
 
   concerning :SearchMethods do
     class_methods do
+      def qualified_column_for(attr)
+        "#{table_name}.#{column_for_attribute(attr).name}"
+      end
+
+      def where_ilike(attr, value)
+        where("lower(#{qualified_column_for(attr)}) LIKE ? ESCAPE E'\\\\'", value.mb_chars.downcase.to_escaped_for_sql_like)
+      end
+
+      # https://www.postgresql.org/docs/current/static/functions-matching.html#FUNCTIONS-POSIX-REGEXP
+      # "(?e)" means force use of ERE syntax; see sections 9.7.3.1 and 9.7.3.4.
+      def where_regex(attr, value)
+        where("#{qualified_column_for(attr)} ~ ?", "(?e)" + value)
+      end
+
       def attribute_matches(attribute, value, **options)
         return all if value.nil?