From fe8db70aed38182ed71fd704a2b52f2adec514fa Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafael=20Fran=C3=A7a?= <rafael@franca.dev>
Date: Wed, 9 Dec 2020 11:59:36 -0500
Subject: [PATCH] Merge pull request #40765 from
 kamipo/allow_nil_should_work_for_casted_value

`allow_nil` should work for casted value in `NumericalityValidator`
---
 activemodel/lib/active_model/validations/numericality.rb  | 6 +++---
 activemodel/lib/active_model/validator.rb                 | 7 ++++---
 .../cases/validations/numericality_validation_test.rb     | 8 ++++++++
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/activemodel/lib/active_model/validations/numericality.rb b/activemodel/lib/active_model/validations/numericality.rb
index a27ed97acac75..9c56417d89b3c 100644
--- a/activemodel/lib/active_model/validations/numericality.rb
+++ b/activemodel/lib/active_model/validations/numericality.rb
@@ -108,8 +108,8 @@ def allow_only_integer?(record)
         end
       end
 
-      def read_attribute_for_validation(record, attr_name)
-        return super if record_attribute_changed_in_place?(record, attr_name)
+      def read_attribute_for_validation(record, attr_name, value)
+        return value if record_attribute_changed_in_place?(record, attr_name)
 
         came_from_user = :"#{attr_name}_came_from_user?"
 
@@ -126,7 +126,7 @@ def read_attribute_for_validation(record, attr_name)
           end
         end
 
-        raw_value || super
+        raw_value || value
       end
 
       def record_attribute_changed_in_place?(record, attr_name)
diff --git a/activemodel/lib/active_model/validator.rb b/activemodel/lib/active_model/validator.rb
index 4a77c7fe5f002..9e2dee9a00f54 100644
--- a/activemodel/lib/active_model/validator.rb
+++ b/activemodel/lib/active_model/validator.rb
@@ -147,8 +147,9 @@ def initialize(options)
     # override +validate_each+ with validation logic.
     def validate(record)
       attributes.each do |attribute|
-        value = read_attribute_for_validation(record, attribute)
+        value = record.read_attribute_for_validation(attribute)
         next if (value.nil? && options[:allow_nil]) || (value.blank? && options[:allow_blank])
+        value = read_attribute_for_validation(record, attribute, value)
         validate_each(record, attribute, value)
       end
     end
@@ -166,8 +167,8 @@ def check_validity!
     end
 
     private
-      def read_attribute_for_validation(record, attr_name)
-        record.read_attribute_for_validation(attr_name)
+      def read_attribute_for_validation(record, attr_name, value)
+        value
       end
   end
 
diff --git a/activerecord/test/cases/validations/numericality_validation_test.rb b/activerecord/test/cases/validations/numericality_validation_test.rb
index ffb8fd17b2951..91cd6a0b0d1f9 100644
--- a/activerecord/test/cases/validations/numericality_validation_test.rb
+++ b/activerecord/test/cases/validations/numericality_validation_test.rb
@@ -110,4 +110,12 @@ def test_aliased_attribute
 
     assert_not_predicate subject, :valid?
   end
+
+  def test_allow_nil_works_for_casted_value
+    model_class.validates_numericality_of(:bank_balance, greater_than: 0, allow_nil: true)
+
+    subject = model_class.new(bank_balance: "")
+
+    assert_predicate subject, :valid?
+  end
 end