Add scale support to ActiveRecord::Validations::NumericalityValidator

activemodel/lib/active_model/validations/numericality.rb

@@ -22,7 +22,7 @@ def check_validity!
         end
       end
 
-      def validate_each(record, attr_name, value, precision: Float::DIG)
+      def validate_each(record, attr_name, value, precision: Float::DIG, scale: nil)
         came_from_user = :"#{attr_name}_came_from_user?"
 
         if record.respond_to?(came_from_user)
@@ -43,7 +43,7 @@ def validate_each(record, attr_name, value, precision: Float::DIG)
           raw_value = value
         end
 
-        unless is_number?(raw_value, precision)
+        unless is_number?(raw_value, precision, scale)
           record.errors.add(attr_name, :not_a_number, **filtered_options(raw_value))
           return
         end
@@ -53,7 +53,7 @@ def validate_each(record, attr_name, value, precision: Float::DIG)
           return
         end
 
-        value = parse_as_number(raw_value, precision)
+        value = parse_as_number(raw_value, precision, scale)
 
         options.slice(*CHECKS.keys).each do |option, option_value|
           case option
@@ -69,7 +69,7 @@ def validate_each(record, attr_name, value, precision: Float::DIG)
               option_value = record.send(option_value)
             end
 
-            option_value = parse_as_number(option_value, precision)
+            option_value = parse_as_number(option_value, precision, scale)
 
             unless value.send(CHECKS[option], option_value)
               record.errors.add(attr_name, option, **filtered_options(value).merge!(count: option_value))
@@ -79,20 +79,24 @@ def validate_each(record, attr_name, value, precision: Float::DIG)
       end
 
     private
-      def parse_as_number(raw_value, precision)
+      def parse_as_number(raw_value, precision, scale)
         if raw_value.is_a?(Float)
-          raw_value.to_d(precision)
+          parse_float(raw_value, precision, scale)
         elsif raw_value.is_a?(Numeric)
           raw_value
         elsif is_integer?(raw_value)
           raw_value.to_i
         elsif !is_hexadecimal_literal?(raw_value)
-          Kernel.Float(raw_value).to_d(precision)
+          parse_float(Kernel.Float(raw_value), precision, scale)
         end
       end
 
-      def is_number?(raw_value, precision)
-        !parse_as_number(raw_value, precision).nil?
+      def parse_float(raw_value, precision, scale)
+        (scale ? raw_value.truncate(scale) : raw_value).to_d(precision)
+      end
+
+      def is_number?(raw_value, precision, scale)
+        !parse_as_number(raw_value, precision, scale).nil?
       rescue ArgumentError, TypeError
         false
       end

activerecord/CHANGELOG.md

+*   Add scale support to `ActiveRecord::Validations::NumericalityValidator`.
+
+    *Gannon McGibbon*
+
 *   Find orphans by looking for missing relations through chaining `where.missing`:
 
     Before:

activerecord/lib/active_record/validations/numericality.rb

@@ -3,15 +3,20 @@
 module ActiveRecord
   module Validations
     class NumericalityValidator < ActiveModel::Validations::NumericalityValidator # :nodoc:
-      def validate_each(record, attribute, value, precision: nil)
-        precision = [column_precision_for(attribute, record) || BigDecimal.double_fig, BigDecimal.double_fig].min
-        super
+      def validate_each(record, attribute, value, precision: nil, scale: nil)
+        precision = [column_precision_for(record, attribute) || BigDecimal.double_fig, BigDecimal.double_fig].min
+        scale     = column_scale_for(record, attribute)
+        super(record, attribute, value, precision: precision, scale: scale)
       end
 
       private
-        def column_precision_for(attribute, record)
+        def column_precision_for(record, attribute)
           record.class.type_for_attribute(attribute.to_s)&.precision
         end
+
+        def column_scale_for(record, attribute)
+          record.class.type_for_attribute(attribute.to_s)&.scale
+        end
     end
 
     module ClassMethods

activerecord/test/cases/validations/numericality_validation_test.rb

@@ -12,10 +12,10 @@ def setup
 
   def test_column_with_precision
     model_class.validates_numericality_of(
-      :bank_balance, equal_to: 10_000_000.12
+      :unscaled_bank_balance, equal_to: 10_000_000.12
     )
 
-    subject = model_class.new(bank_balance: 10_000_000.121)
+    subject = model_class.new(unscaled_bank_balance: 10_000_000.121)
 
     assert_predicate subject, :valid?
   end
@@ -30,6 +30,16 @@ def test_column_with_precision_higher_than_double_fig
     assert_predicate subject, :valid?
   end
 
+  def test_column_with_scale
+    model_class.validates_numericality_of(
+      :bank_balance, greater_than: 10
+    )
+
+    subject = model_class.new(bank_balance: 10.001)
+
+    assert_not_predicate subject, :valid?
+  end
+
   def test_no_column_precision
     model_class.validates_numericality_of(
       :decimal_number, equal_to: 1_000_000_000.123454
@@ -70,4 +80,26 @@ def self.name
 
     assert_predicate(subject, :valid?)
   end
+
+  def test_virtual_attribute_with_precision
+    model_class.attribute(:virtual_decimal_number, :decimal, precision: 5)
+    model_class.validates_numericality_of(
+      :virtual_decimal_number, equal_to: 123.45
+    )
+
+    subject = model_class.new(virtual_decimal_number: 123.455)
+
+    assert_predicate subject, :valid?
+  end
+
+  def test_virtual_attribute_with_scale
+    model_class.attribute(:virtual_decimal_number, :decimal, scale: 2)
+    model_class.validates_numericality_of(
+      :virtual_decimal_number, greater_than: 1
+    )
+
+    subject = model_class.new(virtual_decimal_number: 1.001)
+
+    assert_not_predicate subject, :valid?
+  end
 end

activerecord/test/schema/schema.rb

@@ -580,6 +580,7 @@
   create_table :numeric_data, force: true do |t|
     t.decimal :bank_balance, precision: 10, scale: 2
     t.decimal :big_bank_balance, precision: 15, scale: 2
+    t.decimal :unscaled_bank_balance, precision: 10
     t.decimal :world_population, precision: 20, scale: 0
     t.decimal :my_house_population, precision: 2, scale: 0
     t.decimal :decimal_number