Handle :if => :predicate? methods like :if => :predicate

[ajsharp]

• Rails version: 5.2.3
• Algolia Rails integration version: 1.22.0
• Algolia Client Version: 1.26.0
• Language Version: 2.5.5

Description

This library has some logic where, if your indexing is conditioned on a particular attribute, the library will figure out if that attribute value has changed, and add/delete the object in algolia appropriately. However, I had some code like this, and this functionality wasn't working:

algoliasearch :if => :active? do
# ...
end

After digging through the library, I realized it wasn't working because of this code:

algoliasearch-rails/lib/algoliasearch-rails.rb

Line 934 in 360e47d

method_name = "#{attr_name}_changed?"

If you mistakenly pass do :if => :active? instead of :if => :active, this line will check for a method called active?_changed?, which obviously doesn't exist. It would be great if this library should automatically handle predicate methods that are aliases for attribute methods.

Happy to contribute a PR to add this functionality.