### New features

* [#291](https://github.com/rubocop/rubocop-rails/pull/291): Add new `Rails/SquishedSQLHeredocs` cop. ([@mobilutz][])
* [#52](https://github.com/rubocop/rubocop-rails/issues/52): Add new `Rails/AfterCommitOverride` cop. ([@fatkodima][])
* [#323](https://github.com/rubocop/rubocop-rails/pull/323): Add new `Rails/OrderById` cop. ([@fatkodima][])
* [#274](https://github.com/rubocop/rubocop-rails/pull/274): Add new `Rails/WhereNot` cop. ([@fatkodima][])
* [#311](https://github.com/rubocop/rubocop-rails/issues/311): Make `Rails/HelperInstanceVariable` aware of memoization. ([@koic][])
* [#332](https://github.com/rubocop/rubocop-rails/issues/332): Fix `Rails/ReflectionClassName` cop false negative when relation had a scope parameter. ([@bubaflub][])

### Bug fixes

* [#315](https://github.com/rubocop/rubocop-rails/pull/315): Allow to use frozen scope for `Rails/UniqueValidationWithoutIndex`. ([@krim][])
* [#313](https://github.com/rubocop/rubocop-rails/pull/313): Fix `Rails/ActiveRecordCallbacksOrder` to preserve the original callback execution order. ([@eugeneius][])
* [#319](https://github.com/rubocop/rubocop-rails/issues/319): Fix a false positive for `Rails/Inquiry` when `#inquiry`'s receiver is a variable. ([@koic][])
* [#327](https://github.com/rubocop/rubocop-rails/pull/327): Fix `Rails/ContentTag` autocorrect to handle html5 tag names with hyphens. ([@jaredmoody][])

### Changes

* [#312](https://github.com/rubocop/rubocop-rails/pull/312): Mark `Rails/MailerName` as unsafe for auto-correct. ([@eugeneius][])
* [#294](https://github.com/rubocop/rubocop-rails/pull/294): Update `Rails/ReversibleMigration` to register offenses for `remove_columns` and `remove_index`. ([@philcoggins][])
* [#310](https://github.com/rubocop/rubocop-rails/issues/310): Add `EnforcedStyle` to `Rails/PluckInWhere`. By default, it does not register an offense if `pluck` method's receiver is a variable. ([@koic][])
* [#320](https://github.com/rubocop/rubocop-rails/pull/320): Mark `Rails/UniqBeforePluck` as unsafe auto-correction. ([@kunitoo][])
* [#324](https://github.com/rubocop/rubocop-rails/pull/324): Make `Rails/IndexBy` and `Rails/IndexWith` aware of `to_h` with block. ([@eugeneius][])
* [#341](https://github.com/rubocop/rubocop-rails/pull/341): Make `Rails/WhereExists` configurable to allow `where(...).exists?` to be the preferred style. ([@dvandersluis][])

[@mobilutz]: https://github.com/mobilutz
[@fatkodima]: https://github.com/fatkodima
[@koic]: https://github.com/koic
[@bubaflub]: https://github.com/bubaflub
[@krim]: https://github.com/krim
[@eugeneius]: https://github.com/eugeneius
[@jaredmoody]: https://github.com/jaredmoody
[@philcoggins]: https://github.com/philcoggins
[@kunitoo]: https://github.com/kunitoo
[@dvandersluis]: https://github.com/dvandersluis
