Merge pull request #41410 from eileencodes/define-empty-result

Add ActiveRecord::Result.empty

activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb

@@ -65,7 +65,7 @@ def select_all(arel, name = nil, binds = [], preparable: nil, async: false)
 
         select(sql, name, binds, prepare: prepared_statements && preparable, async: async && FutureResult::SelectAll)
       rescue ::RangeError
-        ActiveRecord::Result.new([], [])
+        ActiveRecord::Result.empty
       end
 
       # Returns a record hash with the column names as keys and column values

activerecord/lib/active_record/future_result.rb

@@ -90,7 +90,7 @@ class SelectAll < FutureResult # :nodoc:
           def exec_query(*, **)
             super
           rescue ::RangeError
-            ActiveRecord::Result.new([], [])
+            ActiveRecord::Result.empty
           end
       end
   end

activerecord/lib/active_record/relation/calculations.rb

@@ -195,7 +195,7 @@ def pluck(*column_names)
         relation.select_values = columns
         result = skip_query_cache_if_necessary do
           if where_clause.contradiction?
-            ActiveRecord::Result.new([], [])
+            ActiveRecord::Result.empty
           else
             klass.connection.select_all(relation.arel, "#{klass.name} Pluck")
           end

activerecord/lib/active_record/result.rb

@@ -36,6 +36,10 @@ class Result
 
     attr_reader :columns, :rows, :column_types
 
+    def self.empty # :nodoc:
+      EMPTY
+    end
+
     def initialize(columns, rows, column_types = {})
       @columns      = columns
       @rows         = rows
@@ -43,6 +47,9 @@ def initialize(columns, rows, column_types = {})
       @column_types = column_types
     end
 
+    EMPTY = new([].freeze, [].freeze, {}.freeze)
+    private_constant :EMPTY
+
     # Returns true if this result set includes the column named +name+
     def includes_column?(name)
       @columns.include? name