Support filtering by multiple selected values

app/assets/javascripts/rails_admin/ra.filter-box.js

@@ -99,6 +99,10 @@
               $('<a href="#" class="switch-select"></a>')
               .append($('<i></i>').addClass('icon-' + (multiple_values ? 'minus' : 'plus')))
             );
+          additional_control =
+            $('<input class="additional-fieldset default input-sm form-control" type="hidden" />')
+            .prop('value', field_operator)
+            .prop('name', operator_name);
         break;
         case 'string':
         case 'text':

app/helpers/rails_admin/main_helper.rb

@@ -67,6 +67,7 @@ def ordered_filter_string
         end
         case field.type
         when :enum
+          options[:operator] = field.search_operator
           options[:select_options] = options_for_select(field.with(object: @abstract_model.model.new).enum, filter_hash['v'])
         when :date, :datetime, :time
           options[:datetimepicker_format] = field.parser.to_momentjs
@@ -76,7 +77,7 @@ def ordered_filter_string
         options[:type]  = field.type
         options[:value] = filter_hash['v']
         options[:label] = field.label
-        options[:operator] = filter_hash['o']
+        options[:operator] = filter_hash['o'] if filter_hash['o'].present?
         %{$.filters.append(#{options.to_json});}
       end.join("\n").html_safe if ordered_filters
     end

lib/rails_admin/abstract_model.rb

@@ -159,6 +159,8 @@ def build_statement_for_integer_decimal_or_float
           case @operator
           when 'between'
             range_filter(range_begin, range_end)
+          when 'in'
+            ["(#{@column} IN (?))", Array.wrap(@value)]
           else
             column_for_value(val) if val
           end

lib/rails_admin/config.rb

@@ -198,7 +198,7 @@ def current_user_method(&block)
       end
 
       def default_search_operator=(operator)
-        if %w(default like starts_with ends_with is =).include? operator
+        if %w(default like starts_with ends_with is in =).include? operator
           @default_search_operator = operator
         else
           raise(ArgumentError.new("Search operator '#{operator}' not supported"))