Merge pull request rails#52416 from spickermann/fix-nested-error-for-singular-associations

[Rails 7.2.0.beta3] Fix bug with indexed nested error for singular associations

Author: byroot

activerecord/lib/active_record/associations/association.rb

@@ -210,6 +210,12 @@ def create!(attributes = nil, &block)
         _create_record(attributes, true, &block)
       end
 
+      # Whether the association represent a single record
+      # or a collection of records.
+      def collection?
+        false
+      end
+
       private
         # Reader and writer methods call this so that consistent errors are presented
         # when the association target class does not exist.

activerecord/lib/active_record/associations/collection_association.rb

@@ -313,6 +313,10 @@ def find_from_target?
           target.any? { |record| record.new_record? || record.changed? }
       end
 
+      def collection?
+        true
+      end
+
       private
         def transaction(&block)
           reflection.klass.transaction(&block)

activerecord/lib/active_record/associations/nested_error.rb

@@ -18,7 +18,7 @@ def initialize(association, inner_error)
         def compute_attribute(inner_error)
           association_name = association.reflection.name
 
-          if index_errors_setting && index
+          if association.collection? && index_errors_setting && index
             "#{association_name}[#{index}].#{inner_error.attribute}".to_sym
           else
             "#{association_name}.#{inner_error.attribute}".to_sym

activerecord/test/cases/associations/nested_error_test.rb

@@ -74,4 +74,43 @@ def self.name; "Guitar"; end
     assert_equal "is not a number", error.message
     assert_equal guitar, error.base
   end
+
+  class AssociationsNestedErrorWithSingularAssociationTest < ActiveRecord::TestCase
+    def setup
+      pet_class = Class.new(ActiveRecord::Base) do
+        self.table_name = "pets"
+        def self.name; "Pet"; end
+
+        validates :name, presence: true
+      end
+
+      @owner_class = Class.new(ActiveRecord::Base) do
+        self.table_name = "owners"
+        def self.name; "Owner"; end
+
+        has_one :pet, anonymous_class: pet_class
+        accepts_nested_attributes_for :pet
+        validates_associated :pet
+      end
+    end
+
+    test "no index when singular association" do
+      old_attribute_config = ActiveRecord.index_nested_attribute_errors
+      ActiveRecord.index_nested_attribute_errors = true
+
+      owner = @owner_class.new(pet_attributes: { name: nil })
+      owner.valid?
+
+      error = owner.errors.objects.first
+
+      assert_equal ActiveRecord::Associations::NestedError, error.class
+      assert_equal owner.pet.errors.objects.first, error.inner_error
+      assert_equal :"pet.name", error.attribute
+      assert_equal :blank, error.type
+      assert_equal "can't be blank", error.message
+      assert_equal owner, error.base
+    ensure
+      ActiveRecord.index_nested_attribute_errors = old_attribute_config
+    end
+  end
 end