6 files changed, 25 insertions, 9 deletions
diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 5d04551125..c91e6662c9 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,8 @@
+*   Using `group` with an attribute that has a custom type will properly cast
+    the hash keys after calling a calculation method like `count`. Fixes #25595.
+
+    *Sean Griffin*
+
 *   Fix the generated `#to_param` method to use `omission: ''` so that
     the resulting output is actually up to 20 characters, not
     effectively 17 to leave room for the default "...".
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
index eb2268157b..3384012c49 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
@@ -159,7 +159,7 @@ module ActiveRecord
       end
 
       # Returns 62. SQLite supports index names up to 64
-      # characters. The rest is used by rails internally to perform
+      # characters. The rest is used by Rails internally to perform
       # temporary rename operations
       def allowed_index_name_length
         index_name_length - 2
diff --git a/activerecord/lib/active_record/model_schema.rb b/activerecord/lib/active_record/model_schema.rb
index 7996c32bbc..114686c5d3 100644
--- a/activerecord/lib/active_record/model_schema.rb
+++ b/activerecord/lib/active_record/model_schema.rb
@@ -282,8 +282,12 @@ module ActiveRecord
       #
       # +attr_name+ The name of the attribute to retrieve the type for. Must be
       # a string
-      def type_for_attribute(attr_name)
-        attribute_types[attr_name]
+      def type_for_attribute(attr_name, &block)
+        if block
+          attribute_types.fetch(attr_name, &block)
+        else
+          attribute_types[attr_name]
+        end
       end
 
       # Returns a hash where the keys are column names and the values are
diff --git a/activerecord/lib/active_record/railtie.rb b/activerecord/lib/active_record/railtie.rb
index 98ea425d16..2c0ca62924 100644
--- a/activerecord/lib/active_record/railtie.rb
+++ b/activerecord/lib/active_record/railtie.rb
@@ -3,7 +3,7 @@ require "rails"
 require "active_model/railtie"
 
 # For now, action_controller must always be present with
-# rails, so let's make sure that it gets required before
+# Rails, so let's make sure that it gets required before
 # here. This is needed for correctly setting up the middleware.
 # In the future, this might become an optional require.
 require "action_controller/railtie"
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb
index d6d92b8607..a97b71815a 100644
--- a/activerecord/lib/active_record/relation/calculations.rb
+++ b/activerecord/lib/active_record/relation/calculations.rb
@@ -312,8 +312,10 @@ module ActiveRecord
 
       Hash[calculated_data.map do |row|
         key = group_columns.map { |aliaz, col_name|
-          column = calculated_data.column_types.fetch(aliaz) do
-            type_for(col_name)
+          column = type_for(col_name) do
+            calculated_data.column_types.fetch(aliaz) do
+              Type::Value.new
+            end
           end
           type_cast_calculated_value(row[aliaz], column)
         }
@@ -346,9 +348,9 @@ module ActiveRecord
       @klass.connection.table_alias_for(table_name)
     end
 
-    def type_for(field)
+    def type_for(field, &block)
       field_name = field.respond_to?(:name) ? field.name.to_s : field.to_s.split('.').last
-      @klass.type_for_attribute(field_name)
+      @klass.type_for_attribute(field_name, &block)
     end
 
     def type_cast_calculated_value(value, type, operation = nil)
diff --git a/activerecord/test/cases/calculations_test.rb b/activerecord/test/cases/calculations_test.rb
index cfae700159..6acfec0621 100644
--- a/activerecord/test/cases/calculations_test.rb
+++ b/activerecord/test/cases/calculations_test.rb
@@ -1,4 +1,5 @@
 require "cases/helper"
+require "models/book"
 require 'models/club'
 require 'models/company'
 require "models/contract"
@@ -25,7 +26,7 @@ class NumericData < ActiveRecord::Base
 end
 
 class CalculationsTest < ActiveRecord::TestCase
-  fixtures :companies, :accounts, :topics, :speedometers, :minivans
+  fixtures :companies, :accounts, :topics, :speedometers, :minivans, :books
 
   def test_should_sum_field
     assert_equal 318, Account.sum(:credit_limit)
@@ -793,4 +794,8 @@ class CalculationsTest < ActiveRecord::TestCase
     assert_equal 50, result[1].credit_limit
     assert_equal 50, result[2].credit_limit
   end
+
+  def test_group_by_attribute_with_custom_type
+    assert_equal({ "proposed" => 2, "published" => 2 }, Book.group(:status).count)
+  end
 end