Merge pull request #15895 from sgrif/sg-numeric-changes

Always assume strings with non-numeric characters change numeric types

activerecord/CHANGELOG.md

+*   Assume numeric types have changed if they were assigned to a value that
+    would fail numericality validation, regardless of the old value. Previously
+    this would only occur if the old value was 0.
+
+    Example:
+
+        model = Model.create!(number: 5)
+        model.number = '5wibble'
+        model.number_changed? # => true
+
+    Fixes #14731.
+
+    *Sean Griffin*
+
 *   `reload` no longer merges with the existing attributes.
     The attribute hash is fully replaced. The record is put into the same state
     as it would be with `Model.find(model.id)`.

activerecord/lib/active_record/type/numeric.rb

@@ -16,13 +16,13 @@ def type_cast(value)
       end
 
       def changed?(old_value, _new_value, new_value_before_type_cast) # :nodoc:
-        super || zero_to_non_number?(old_value, new_value_before_type_cast)
+        super || number_to_non_number?(old_value, new_value_before_type_cast)
       end
 
       private
 
-      def zero_to_non_number?(old_value, new_value_before_type_cast)
-        old_value == 0 && non_numeric_string?(new_value_before_type_cast)
+      def number_to_non_number?(old_value, new_value_before_type_cast)
+        old_value != nil && non_numeric_string?(new_value_before_type_cast)
       end
 
       def non_numeric_string?(value)

activerecord/test/cases/types_test.rb

@@ -79,11 +79,29 @@ def test_type_cast_nan_and_infinity_to_integer
         assert_nil type.type_cast_from_user(1.0/0.0)
       end
 
+      def test_changing_integers
+        type = Type::Integer.new
+
+        assert type.changed?(5, 5, '5wibble')
+        assert_not type.changed?(5, 5, '5')
+        assert_not type.changed?(5, 5, '5.0')
+        assert_not type.changed?(nil, nil, nil)
+      end
+
       def test_type_cast_float
         type = Type::Float.new
         assert_equal 1.0, type.type_cast_from_user("1")
       end
 
+      def test_changing_float
+        type = Type::Float.new
+
+        assert type.changed?(5.0, 5.0, '5wibble')
+        assert_not type.changed?(5.0, 5.0, '5')
+        assert_not type.changed?(5.0, 5.0, '5.0')
+        assert_not type.changed?(nil, nil, nil)
+      end
+
       def test_type_cast_decimal
         type = Type::Decimal.new
         assert_equal BigDecimal.new("0"), type.type_cast_from_user(BigDecimal.new("0"))