Question

对不起，新手问题，大家好。这是：

我有一个看起来像这样的哈希：

{ "id" => { :task => [ { :due => Mon Dec 20 00:00:00 UTC 2010, completed: => "2010-12-18T17:29:57Z", :priority => "1", ... } ] , ... } , ... }

要对此进行排序，我使用：

tasks = hash.with_indifferent_access

tasks.sort_by { |k,v| [ v['task'][0]['completed'], v['task'][0]['due'], v['task'][0]['priority'] ] }

只要具有日期值，就可以正常工作。当它没有允许的日期值时，它看起来像这样：

:due => ""

然后我收到Rails错误说：“Array与Array的比较失败。”

我尝试将三元和其他逻辑设置为默认为远程日期，如果：due为空，但看起来这在sort_by块中是不可能的。

任何想法如何舔这个？非常感谢！

Answer 1

这是一个示例，假设“due”是一个字符串，当为空时，您希望它在具有相同完成值的其他任务之前进行排序。我们的想法是将有效日期和空字符串转换为相同的可比数据类型（在这种情况下是自纪元以来的整数秒数）。我故意忽略了与您的问题无关的设置细节。

# Required for Time.parse
require 'time'

tasks = [
  {
    completed: "2010-12-18T17:29:57Z",
    due:       "Mon Dec 20 00:00:00 UTC 2010",
    priority:  "1"
  },{
    completed: "2010-12-18T17:29:57Z",
    due:       "Mon Dec 20 00:00:00 UTC 2010",
    priority:  "2"
  },{
    completed: "2010-12-18T17:29:57Z",
    due:       "",
    priority:  "1"
  },{
    completed: "2010-12-17T17:29:57Z",
    due:       "Mon Dec 20 00:00:00 UTC 2010",
    priority:  "1"
  },{
    completed: "2010-12-19T17:29:57Z",
    due:       "Mon Dec 20 00:00:00 UTC 2010",
    priority:  "1"
  }
]

require 'pp'
pp tasks.sort_by{ |h| [
  Time.parse(h[:completed]),
  h[:due].empty? ? 0 : Time.parse(h[:due]).to_i,
  h[:priority].to_i
]}
#=> [{:completed=>"2010-12-17T17:29:57Z",
#=>   :due=>"Mon Dec 20 00:00:00 UTC 2010",
#=>   :priority=>"1"},
#=>  {:completed=>"2010-12-18T17:29:57Z", :due=>"", :priority=>"1"},
#=>  {:completed=>"2010-12-18T17:29:57Z",
#=>   :due=>"Mon Dec 20 00:00:00 UTC 2010",
#=>   :priority=>"1"},
#=>  {:completed=>"2010-12-18T17:29:57Z",
#=>   :due=>"Mon Dec 20 00:00:00 UTC 2010",
#=>   :priority=>"2"},
#=>  {:completed=>"2010-12-19T17:29:57Z",
#=>   :due=>"Mon Dec 20 00:00:00 UTC 2010",
#=>   :priority=>"1"}]

在点击空日期值时Rails多sort_by期间出错

1 个答案: