使用has_many声明和：uniq在Rails 4中没有其他参数的弃用警告

Question

所以我发现了

DEPRECATION WARNING: The following options in your Goal.has_many 
:donors declaration are deprecated: :uniq. Please use a scope block 
instead. For example, the following:

    has_many :spam_comments, conditions: { spam: true }, class_name: 
'Comment'

should be rewritten as the following:

has_many :spam_comments, -> { where spam: true }, class_name: 'Comment'

但是我有很多行代码，其中uniq是唯一的参数，例如： has_and_belongs_to_many :accounts, uniq: true

我如何将其写成一个块？我已经尝试过has_and_belongs_to_many :accounts, -> { uniq }，但是我读到在代码行的末尾不能这样写uniq