Merge pull request #50319 from fatkodima/fix-where-for-polymorphic-cpk

Fix predicate builder for polymorphic models referencing models with composite primary keys

activerecord/lib/active_record/relation/predicate_builder/polymorphic_array_value.rb

@@ -43,7 +43,12 @@ module ActiveRecord
 
         def convert_to_id(value)
           if value.is_a?(Base)
-            value._read_attribute(primary_key(value))
+            primary_key = primary_key(value)
+            if primary_key.is_a?(Array)
+              primary_key.map { |column| value._read_attribute(column) }
+            else
+              value._read_attribute(primary_key)
+            end
           elsif value.is_a?(Relation)
             value.select(primary_key(value))
           else

activerecord/test/cases/associations/belongs_to_associations_test.rb

@@ -63,6 +63,12 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     assert_empty Comment.where(author: [])
   end
 
+  def test_where_on_polymorphic_association_with_cpk
+    post = Cpk::Post.create!(title: "Welcome", author: "Mary")
+    post.comments << Cpk::Comment.create!
+    assert_equal 1, Cpk::Comment.where(commentable: post).count
+  end
+
   def test_assigning_belongs_to_on_destroyed_object
     client = Client.create!(name: "Client")
     client.destroy!

activerecord/test/models/cpk.rb

@@ -8,3 +8,5 @@ require_relative "cpk/order_agreement"
 require_relative "cpk/order_tag"
 require_relative "cpk/tag"
 require_relative "cpk/chapter"
+require_relative "cpk/post"
+require_relative "cpk/comment"

activerecord/test/models/cpk/comment.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+module Cpk
+  class Comment < ActiveRecord::Base
+    self.table_name = :cpk_comments
+    belongs_to :commentable, class_name: "Cpk::Post", query_constraints: %i[commentable_title commentable_author], polymorphic: true
+  end
+end

activerecord/test/models/cpk/post.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+module Cpk
+  class Post < ActiveRecord::Base
+    self.table_name = :cpk_posts
+    has_many :comments, class_name: "Cpk::Comment", query_constraints: %i[commentable_title commentable_author], as: :commentable
+  end
+end

activerecord/test/schema/schema.rb

@@ -261,6 +261,17 @@ ActiveRecord::Schema.define do
     t.string :name
   end
 
+  create_table :cpk_posts, primary_key: [:title, :author], force: true do |t|
+    t.string :title
+    t.string :author
+  end
+
+  create_table :cpk_comments, force: true do |t|
+    t.string :commentable_title
+    t.string :commentable_author
+    t.string :commentable_type
+  end
+
   create_table :cpk_reviews, force: true do |t|
     t.integer :author_id
     t.integer :number