列中数组的唯一值

Question

这篇文章很接近：

Rails: select unique values from a column

Model.uniq.pluck(:rating)

效果很好，除了在我的情况下我的列中有一个数组，所以我得到这样的东西：

[["guest"], ["engineer", "manager"], ["engineer"], ["admin"], ["operations"], ["operator"], ["operator", "manager"]]

我希望将这些缩小到最简单的列表（按照字母顺序排列）。

Answer 1

您需要的是Array#flatten和Array#sort

Model.pluck(:rating).flatten
#=>["guest", "engineer", "manager", "engineer", "admin", "operations", "operator", "operator", "manager"]

现在排序：

Model.pluck(:rating).flatten.uniq
#= ["guest", "engineer", "manager", "admin", "operations", "operator"]

Model.pluck(:rating).flatten.uniq.sort
#=> ["admin", "engineer", "guest", "manager", "operations", "operator"]

如果可能有大写单词，请在排序时将其缩写，以确保排序不区分大小写：

Model.pluck(:rating).flatten.uniq.sort_by(&:downcase)