We used "retire" because we translated it literally from the Spanish
verb "retirar" which can mean both "retire" and "withdraw".
Note we're still using "retire" in database fields and method names;
changing that might make it harder to upgrade from a previous version of
CONSUL.
Although it wasn't a real security concern because we were only calling
a `find_by` method based on the user input, it's a good practice to
avoid using constants based on user parameters.
Since we don't use the `find_by` method anymore but we still need to
check the associated record exists, we're changing the validations in
the `RelatedContent` model to do exactly that.
We were manually checking validation rules (like both relationable
objects are present, or they're both the same object) in the controller
and then using the `save!` method.
However, we usually use the `save` method (which checks all validations)
in a condition, and proceed depending on the result.
Now we're taking the same approach here. This means introducing a new
validation rule in the model to check whether both relationable objects
are the same, which is more robust than checking a condition in the
controller.
We were very inconsistent regarding these rules.
Personally I prefer no empty lines around blocks, clases, etc... as
recommended by the Ruby style guide [1], and they're the default values
in rubocop, so those are the settings I'm applying.
The exception is the `private` access modifier, since we were leaving
empty lines around it most of the time. That's the default rubocop rule
as well. Personally I don't have a strong preference about this one.
[1] https://rubystyle.guide/#empty-lines-around-bodies
