Add paper_trail.update_columns (#1037)

* Add paper_trail.update_columns

Add paper_trail.update_columns so you can record a version when using
update_columns (which skips all callbacks, including the after_update
callback).

* Change recordable_object_changes to not have a default for the changes
argument so that we don't need an exception to
Style/MethodCallWithoutArgsParentheses

* Add back the duplication between record_update and
record_update_columns, at @jaredbeck's request

* - 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

@@ -26,6 +26,7 @@ recommendations of [keepachangelog.com](http://keepachangelog.com/).
 
 ### Added
 
+- [#1037](https://github.com/airblade/paper_trail/pull/1037) Add `paper_trail.update_columns`
 - [#961](https://github.com/airblade/paper_trail/issues/961) - Instead of
   crashing when misconfigured Custom Version Classes are used, an error will be
   raised earlier, with a much more helpful message.

lib/paper_trail/record_trail.rb

@@ -226,7 +226,7 @@ def data_for_create
         data[:created_at] = @record.updated_at
       end
       if record_object_changes? && changed_notably?
-        data[:object_changes] = recordable_object_changes
+        data[:object_changes] = recordable_object_changes(changes)
       end
       add_transaction_id_to(data)
       merge_metadata_into(data)
@@ -284,7 +284,7 @@ def record_update(force)
       @in_after_callback = false
     end
 
-    # Returns data for record update
+    # Returns data for record_update
     # @api private
     def data_for_update
       data = {
@@ -296,7 +296,35 @@ def data_for_update
         data[:created_at] = @record.updated_at
       end
       if record_object_changes?
-        data[:object_changes] = recordable_object_changes
+        data[:object_changes] = recordable_object_changes(changes)
+      end
+      add_transaction_id_to(data)
+      merge_metadata_into(data)
+    end
+
+    # @api private
+    def record_update_columns(changes)
+      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
+
+    # Returns data for record_update_columns
+    # @api private
+    def data_for_update_columns(changes)
+      data = {
+        event: @record.paper_trail_event || "update",
+        object: recordable_object,
+        whodunnit: PaperTrail.whodunnit
+      }
+      if record_object_changes?
+        data[:object_changes] = recordable_object_changes(changes)
       end
       add_transaction_id_to(data)
       merge_metadata_into(data)
@@ -322,7 +350,7 @@ def recordable_object
     # otherwise the column is a `text` column, and we must perform the
     # serialization here, using `PaperTrail.serializer`.
     # @api private
-    def recordable_object_changes
+    def recordable_object_changes(changes)
       if @record.class.paper_trail.version_class.object_changes_col_is_json?
         changes
       else
@@ -406,6 +434,28 @@ def touch_with_version(name = nil)
       @record.save!(validate: false)
     end
 
+    # 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]
+      end
+      @record.update_columns(attributes)
+      record_update_columns(changes)
+    end
+
     # Returns the object (not a Version) as it was at the given timestamp.
     def version_at(timestamp, reify_options = {})
       # Because a version stores how its object looked *before* the change,

spec/models/on/empty_array_spec.rb

@@ -21,6 +21,15 @@ module On
       end
     end
 
+    describe ".paper_trail.update_columns" do
+      it "creates a version record" do
+        widget = Widget.create
+        assert_equal 1, widget.versions.length
+        widget.paper_trail.update_columns(name: "Bugle")
+        assert_equal 2, widget.versions.length
+      end
+    end
+
     describe "#update_attributes" do
       it "does not create any version records" do
         record = described_class.create(name: "Alice")

spec/models/widget_spec.rb

@@ -285,6 +285,20 @@
     end
   end
 
+  describe ".paper_trail.update_columns", versioning: true do
+    it "creates a version record" do
+      widget = Widget.create
+      expect(widget.versions.count).to eq(1)
+      Timecop.freeze Time.now do
+        widget.paper_trail.update_columns(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"])
+        expect(widget.versions.last.created_at.to_i).to eq(Time.now.to_i)
+      end
+    end
+  end
+
   describe "#update", versioning: true do
     it "creates a version record" do
       widget = Widget.create