Using `pluck("DISTINCT")` was raising a warning in Rails 5.2:
DEPRECATION WARNING: Dangerous query method (method whose arguments are
used as raw SQL) called with non-attribute argument(s): "DISTINCT
taggings.tag_id". Non-attribute arguments will be disallowed in Rails
6.0. This method should not be called with user-provided values, such as
request parameters or model attributes. Known-safe values can be passed
by wrapping them in Arel.sql().
Since there was only one other use of distinct, I've decided to change
both of them in the same commit, even if the second one wasn't raising a
warning.
The code `where(id: ids)` is equivalent to `where(id: ids.uniq)`.
Since Rails 5 uses `distinct` instead of `uniq` and in most cases where
we use `uniq` with `pluck` we should simply remove the `uniq` call (as
done in this commit), we're also removing the `Rails/UniqBeforePluck`
rubocop rule.
The list of emails for sending newsletters will always be ordered by
user creation date, so it will be easier to debug and to know for
which users the email has been sent.
Why:
Both Newsletters and Email Downloads need the same logic: To extract the
emails from all the users in the segment that have newsletter flag
active, removing all empty email values.
How:
1- UserSegments#user_segment_emails holds that repeated logic and is used
on both Newsletter & EmailDownload.
2- Rename Newsletter#list_of_recipients to list_of_recipient_emails as
it is more descriptive. There is no need to pass entire Users around,
only the emails are needed at Mailer#newsletter method.
3- Cleanup Newsletter#list_of_recipient_emails model spec scenario
Why:
UserSegments are not only used for Newsletters or Email downloads, but
also for internal Global Notifications. We don't want to have that scope
hardcoded inside UserSegments as users that have opted-out from the
newsletter should still be recipients of global notifications.
How:
Removing the scope from the UserSegments `all_users` method that acts as
base for all the other segments. Including that `newsletter` scope only
on the places that is relevant:
* When listing recipients for a newsletter
* When downloading a listing emails that can be newsletter recipients
Also updated relevant tests
