update PgSearchable to accept array of default columns

lib/pg_searchable_regex.rb

@@ -26,7 +26,7 @@ module PgSearchable
       wildcard: true,
       external_cache_data: nil,
       joins: [],
-      default_field: ""
+      default_fields: []
     )
       @ts_search_fields = fields
       @ts_search_fields_mappings = fields_mappings
@@ -36,7 +36,11 @@ module PgSearchable
       @ts_skip_cache_update = skip_callback
       @ts_wildcard = wildcard
       @ts_joins = joins
-      @default_field = default_field.to_s.empty? ? fields.first : default_field.to_sym
+      @default_fields = if default_fields.is_a? Array
+                          default_fields.empty? ? [fields.first] : default_fields
+                        else
+                          default_fields.to_s.empty? ? [fields.first] : [default_fields.to_sym]
+                        end
       ts_add_scope
     end
 
@@ -52,7 +56,7 @@ module PgSearchable
     def ts_search(value)
       return if @ts_search_fields.blank? || value.blank?
       includes(@ts_joins).references(:all).where(
-        TextToSqlQuery.new(value, @ts_search_fields, @default_field, @ts_search_fields_mappings).where_clause).distinct
+        TextToSqlQuery.new(value, @ts_search_fields, @default_fields, @ts_search_fields_mappings).where_clause).distinct
     end
 
     def should_update_cache_field?