Fix bug, when ':dependent => :destroy' violates foreign key constraints

activerecord/CHANGELOG.md

@@ -1,3 +1,10 @@
+*   Move 'dependent: :destroy' handling for 'belongs_to'
+    from 'before_destroy' to 'after_destroy' callback chain
+
+    Fix #12380.
+
+    *Ivan Antropov*
+
 *   Fixed `ActiveRecord::Associations::CollectionAssociation#find`
     when using `has_many` association with `:inverse_of` and finding an array of one element,
     it should return an array of one element too.

activerecord/lib/active_record/associations/builder/association.rb

@@ -69,7 +69,10 @@ def define_extensions(model)
     end
 
     def define_callbacks(model, reflection)
-      add_before_destroy_callbacks(model, name) if options[:dependent]
+      if options[:dependent]
+        check_dependent_options
+        add_destroy_callbacks(model, name)
+      end
       Association.extensions.each do |extension|
         extension.build model, reflection
       end
@@ -110,12 +113,14 @@ def valid_dependent_options
 
     private
 
-    def add_before_destroy_callbacks(model, name)
-      unless valid_dependent_options.include? options[:dependent]
-        raise ArgumentError, "The :dependent option must be one of #{valid_dependent_options}, but is :#{options[:dependent]}"
+      def check_dependent_options
+        unless valid_dependent_options.include? options[:dependent]
+          raise ArgumentError, "The :dependent option must be one of #{valid_dependent_options}, but is :#{options[:dependent]}"
+        end
       end
 
-      model.before_destroy lambda { |o| o.association(name).handle_dependency }
-    end
+      def add_destroy_callbacks(model, name)
+        model.before_destroy lambda { |o| o.association(name).handle_dependency }
+      end
   end
 end

activerecord/lib/active_record/associations/builder/belongs_to.rb

@@ -133,5 +133,9 @@ def add_touch_callbacks(model, reflection)
       model.after_touch   callback
       model.after_destroy callback
     end
+
+    def add_destroy_callbacks(model, name)
+      model.after_destroy lambda { |o| o.association(name).handle_dependency }
+    end
   end
 end

activerecord/lib/active_record/associations/builder/has_one.rb

@@ -20,8 +20,8 @@ def valid_dependent_options
 
     private
 
-    def add_before_destroy_callbacks(model, name)
-      super unless options[:through]
-    end
+      def add_destroy_callbacks(model, name)
+        super unless options[:through]
+      end
   end
 end

activerecord/test/cases/associations/belongs_to_associations_test.rb

@@ -831,3 +831,39 @@ def test_reflect_the_most_recent_change
     assert_equal post.author_id, author2.id
   end
 end
+
+class BelongsToWithForeignKeyTest < ActiveRecord::TestCase
+  def setup
+    ActiveRecord::Schema.define do
+      drop_table :authors, if_exists: true
+      drop_table :author_addresses, if_exists: true
+
+      create_table :author_addresses do |t|
+      end
+
+      exec_query  <<-eos
+        create table authors(
+          id int,
+          author_address_id int,
+          name varchar(255),
+          PRIMARY KEY (id),
+          FOREIGN KEY (author_address_id) REFERENCES author_addresses(id)
+        );
+      eos
+    end
+  end
+
+  def teardown
+    ActiveRecord::Schema.define do
+      drop_table :authors, if_exists: true
+      drop_table :author_addresses, if_exists: true
+    end
+  end
+
+  def test_destroy_linked_models
+    address = AuthorAddress.create!
+    author = Author.create! id: 1, name: "Author", author_address_id: address.id
+
+    author.destroy!
+  end
+end