小编Nac*_*cho的帖子

The standard way to use a React useState Hook is the following:

const [count, setCount] = useState(0);

However this const count variable is clearly going to be reassigned to a different primitive value.

Why then is the variable not defined as let count?

鉴于：

class Account < ApplicationRecord
  belongs_to :super_account, class_name: 'Account', optional: true, foreign_key: 'account_id'
  has_many   :sub_accounts,  class_name: 'Account'
end

查找没有 sub_accounts 的所有帐户的 rails 方法是什么？