- Add Changelog entry for paper_trail.update_columns

- Use a guard in `record_update_columns`
- Use Timecop.freeze so that we can guarantee that an expectation will pass
- Add some comments

CHANGELOG.md

@@ -26,7 +26,7 @@ recommendations of [keepachangelog.com](http://keepachangelog.com/).
 
 ### Added
 
-- None
+- [#1037](https://github.com/airblade/paper_trail/pull/1037) Add `paper_trail.update_columns`
 
 ### Fixed
 

lib/paper_trail/record_trail.rb

@@ -302,16 +302,16 @@ def data_for_update
       merge_metadata_into(data)
     end
 
+    # @api private
     def record_update_columns(changes)
-      if enabled?
-        versions_assoc = @record.send(@record.class.versions_association_name)
-        version = versions_assoc.create(data_for_update_columns(changes))
-        if version.errors.any?
-          log_version_errors(version, :update)
-        else
-          update_transaction_id(version)
-          save_associations(version)
-        end
+      return unless enabled?
+      versions_assoc = @record.send(@record.class.versions_association_name)
+      version = versions_assoc.create(data_for_update_columns(changes))
+      if version.errors.any?
+        log_version_errors(version, :update)
+      else
+        update_transaction_id(version)
+        save_associations(version)
       end
     end
 
@@ -323,7 +323,6 @@ def data_for_update_columns(changes)
         object: recordable_object,
         whodunnit: PaperTrail.whodunnit
       }
-      data[:created_at] = Time.now
       if record_object_changes?
         data[:object_changes] = recordable_object_changes(changes)
       end
@@ -437,13 +436,18 @@ def touch_with_version(name = nil)
 
     # Like the `update_column` method from `ActiveRecord::Persistence`, but also
     # creates a version to record those changes.
+    # @api public
     def update_column(name, value)
       update_columns(name => value)
     end
 
     # Like the `update_columns` method from `ActiveRecord::Persistence`, but also
     # creates a version to record those changes.
+    # @api public
     def update_columns(attributes)
+      # `@record.update_columns` skips dirty tracking, so we can't just use `@record.changes` or
+      # @record.saved_changes` from `ActiveModel::Dirty`. We need to build our own hash with the
+      # changes that will be made directly to the database.
       changes = {}
       attributes.each do |k, v|
         changes[k] = [@record[k], v]

spec/models/widget_spec.rb

@@ -289,9 +289,8 @@
     it "creates a version record" do
       widget = Widget.create
       expect(widget.versions.count).to eq(1)
-      Timecop.travel 1.second.since # because MySQL lacks fractional seconds precision
+      Timecop.freeze Time.now
       widget.paper_trail.update_columns(name: "Bugle")
-      # widget.update_attributes(name: "Bugle")
       expect(widget.versions.count).to eq(2)
       expect(widget.versions.last.event).to(eq("update"))
       expect(widget.versions.last.changeset[:name]).to eq([nil, "Bugle"])