如何在ruby中使用rindex查找索引

Question

我有以下数组

"testArr": [
  {
    "start": "2020-10-9",
    "dest": "2020-10-10"
  },
  {
    "start": "2020-10-10",
    "dest": null
  },
  {
    "start": null,
    "dest": null
  }
]

我想要获取开始不为空，但目标为空的元素的索引。如下所示：

index = testArr.rindex{|x| x.start.nil? && x.dest.nil?}

puts index

但是我一直收到语法错误。我是ruby的新手。有谁能帮上忙吗？

谢谢

Answer 1

假设testArr为Array of Hashes，您必须像hash[key]一样访问散列键的值，而不是像hash.key那样访问散列键的值，即用x[:start]代替x.start

下面的内容应该可以用

index = testArr.rindex {|x| x[:start].present? && x[:dest].nil?}

检查以下内容

[4] pry(main)> testArr = [ {"start": "2020-10-9", "dest": "2020-10-10" }, {"start": "2020-10-10", "dest": nil}, {"start": nil, "dest": nil}]
=> [{:start=>"2020-10-9", :dest=>"2020-10-10"}, {:start=>"2020-10-10", :dest=>nil}, {:start=>nil, :dest=>nil}]
[5] pry(main)> testArr.rindex {|x| x[:start].present? && x[:dest].nil?}
=> 1