Never attempt to write virtual attributes to the database

Currently the place where we limit what gets sent to the database is in
the implementation for `partial_writes`. We should also be restricting
it to column names when partial writes are turned off.

Note that we're using `&` instead of just defaulting to
`self.class.column_names`, as the instance version of `attribute_names`
does not include attributes which are uninitialized (were not included
in the select clause)

1 files changed, 19 insertions, 0 deletions

diff --git a/activerecord/test/cases/dirty_test.rb b/activerecord/test/cases/dirty_test.rb
index 14c4e3cbd4..d1a7366f5f 100644
--- a/activerecord/test/cases/dirty_test.rb
+++ b/activerecord/test/cases/dirty_test.rb
@@ -736,6 +736,25 @@ class DirtyTest < ActiveRecord::TestCase
     assert record.save
   end
 
+  test "virtual attributes are not written with partial_writes off" do
+    original_partial_writes = ActiveRecord::Base.partial_writes
+    begin
+      ActiveRecord::Base.partial_writes = false
+      klass = Class.new(ActiveRecord::Base) do
+        self.table_name = "people"
+        attribute :non_persisted_attribute, :string
+      end
+
+      record = klass.new(first_name: "Sean")
+      record.non_persisted_attribute_will_change!
+
+      assert_predicate record, :non_persisted_attribute_changed?
+      assert record.save
+    ensure
+      ActiveRecord::Base.partial_writes = original_partial_writes
+    end
+  end
+
   test "mutating and then assigning doesn't remove the change" do
     pirate = Pirate.create!(catchphrase: "arrrr")
     pirate.catchphrase << " matey!"