ActiveRecord::ReturningAttributes

ReturningAttributes provides a way to populate model attributes with database-backed default values or values set via database triggers when creating or updating single records without executing additional database queries.

Slightly Longer Description

When having database-backed default values (like NOW()) or values set via database triggers, we don't get to see them when creating or updating records in Rails. This is because when inserting records, the PostgreSQL RETURNING clause only states the id (or a different primary key) column, other columns are not returned back to Rails-land. Similar to inserts, updates don't get to see those values because there's no RETURNING clause involved at all.

Internally this library changes the RETURNING clause for inserts and adds it for updates so we don't have to reload records.

Caveats:

• PostgreSQL only
• Only tested in Rails 6.0.0.rc1
• Overrides ActiveRecord core code

Installation

Add this line to your application's Gemfile:

gem 'active_record-returning_attributes', github: 'tbuehlmann/active_record-returning_attributes'

And then execute:

$ bundle install

Usage

Assume having a database-backed default value for the uuid column or a trigger that sets the value.

Before:

class Project < ApplicationRecord
end

project = Project.create
project.uuid # => nil

project.reload
project.uuid # => '2b57df54-3768-45c6-ad10-aeec028e7735'

After:

class Project < ApplicationRecord
  self.returning_attributes = [:uuid]
end

project = Project.create
project.uuid # => '2b57df54-3768-45c6-ad10-aeec028e7735'

By setting self.returning_attributes, ActiveRecord will request those columns via the RETURNING clause and populate the corresponding attributes in your model.

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/tbuehlmann/active_record-returning_attributes.

License

The gem is available as open source under the terms of the MIT License.