Limit ActiveRecord strings to 191 characters to avoid index too long errors with MySQL utf8mb4 encoding

active_record_mysql_utf8mb4_patch.rb

# config/initializers/active_record_patch.rb

require 'active_record/connection_adapters/abstract_mysql_adapter'

module ActiveRecord
  module ConnectionAdapters
    class AbstractMysqlAdapter
      NATIVE_DATABASE_TYPES[:string] = { name: "varchar", limit: 191 }
    end
  end
end