Refactor NonexistentFieldsDetector a bit

Author: andrykonchin

lib/dynamoid/criteria/chain.rb

@@ -54,15 +54,9 @@ def where(args)
           Dynamoid.logger.warn(detector.warning_message)
         end
 
-        nonexistent_fields = NonexistentFieldsDetector.new(args, @source).fields
-        if nonexistent_fields.present?
-          fields_list = nonexistent_fields.map { |s| "`#{s}`" }.join(', ')
-          fields_count = nonexistent_fields.size
-
-          Dynamoid.logger.warn(
-            "where conditions contain nonexistent" \
-            " field #{ 'name'.pluralize(fields_count) } #{ fields_list }"
-          )
+        detector = NonexistentFieldsDetector.new(args, @source)
+        if detector.found?
+          Dynamoid.logger.warn(detector.warning_message)
         end
 
         query.update(args.symbolize_keys)

lib/dynamoid/criteria/nonexistent_fields_detector.rb

@@ -6,19 +6,31 @@ class NonexistentFieldsDetector
       def initialize(conditions, source)
         @conditions = conditions
         @source = source
+        @nonexistent_fields = nonexistent_fields
       end
 
-      def fields
-        fields_from_conditions - fields_existent
+      def found?
+        @nonexistent_fields.present?
+      end
+
+      def warning_message
+        return unless found?
+
+        fields_list = @nonexistent_fields.map { |s| "`#{s}`" }.join(', ')
+        count = @nonexistent_fields.size
+
+        "where conditions contain nonexistent" \
+          " field #{ 'name'.pluralize(count) } #{ fields_list }"
       end
 
       private
 
+      def nonexistent_fields
+        fields_from_conditions - fields_existent
+      end
+
       def fields_from_conditions
-        @conditions.keys.map do |s|
-          name, _ = s.to_s.split('.')
-          name
-        end.map(&:to_sym)
+        @conditions.keys.map { |s| s.to_s.split('.')[0].to_sym }
       end
 
       def fields_existent