Merge pull request rails#45790 from mikeletscher/bind-attribute-primary-key-relation

[AR] Fix uniqueness validation on association not using overridden PK

Author: yahonda

activerecord/lib/active_record/relation.rb

@@ -45,7 +45,7 @@ def initialize_copy(other)
     def bind_attribute(name, value) # :nodoc:
       if reflection = klass._reflect_on_association(name)
         name = reflection.foreign_key
-        value = value.read_attribute(reflection.klass.primary_key) unless value.nil?
+        value = value.read_attribute(reflection.association_primary_key) unless value.nil?
       end
 
       attr = table[name]

activerecord/test/cases/validations/uniqueness_validation_test.rb

@@ -11,6 +11,7 @@
 require "models/author"
 require "models/person"
 require "models/essay"
+require "models/keyboard"
 
 class Wizard < ActiveRecord::Base
   self.abstract_class = true
@@ -70,6 +71,14 @@ def set_author
   end
 end
 
+class LessonWithUniqKeyboard < ActiveRecord::Base
+  self.table_name = "lessons"
+
+  belongs_to :keyboard, primary_key: :name, foreign_key: :name
+
+  validates_uniqueness_of :keyboard
+end
+
 class UniquenessValidationTest < ActiveRecord::TestCase
   INT_MAX_VALUE = 2147483647
 
@@ -766,6 +775,15 @@ def test_uniqueness_on_relation
     Event.delete_all
   end
 
+  def test_uniqueness_on_custom_relation_primary_key
+    Keyboard.create!(name: "Keyboard #1")
+    LessonWithUniqKeyboard.create!(name: "Keyboard #1")
+
+    another = LessonWithUniqKeyboard.new(name: "Keyboard #1")
+    assert_not_predicate another, :valid?
+    assert_equal ["has already been taken"], another.errors[:keyboard]
+  end
+
   def test_index_of_sublist_of_columns
     Topic.validates_uniqueness_of(:title, scope: :author_name)
     @connection.add_index(:topics, :author_name, unique: true, name: :topics_index)