jq - 从 JQ 中的稀疏对象数组生成新数组

Question

我有一个要用 JQ 处理的 JSON 文件。它在另一个对象中有一个对象数组，带有一个我想用来填充新数组的键。

在我的实际用例中，它嵌套在许多其他的绒毛中，还有更多的数组，但将其作为此类事物的一个更简单但具有代表性的示例:

{
  "numbers": [
    {
      "numeral": 1,
      "ordinal": "1st",
      "word": "One"
    },
    {
      "numeral": 2,
      "ordinal": "2nd",
      "word": "Two"
    },
    {
      "numeral": 5,
      "ordinal": "5th",
      "word": "Five"
    },
    {
      "some-other-fluff-i-want-to-ignore": true
    }
  ]
}

我想用JQ根据元素得到一个新的数组，忽略一些元素并处理缺失的元素。例如

[
  "The 1st word is One",
  "The 2nd word is Two",
  "Wot no number 3?",
  "Wot no number 4?",
  "The 5th word is Five"
]

在循环中为现有的元素执行此操作非常简单、简洁和优雅:

.numbers | map( . | select( .numeral) | [ "The", .ordinal, "word is", .word ] | join (" "))

但我找不到处理缺失条目的方法。我有一些可以正常工作的代码:

.numbers | [
  ( .[] | select(.numeral == 1) | ( [ "The", .ordinal, "word is", .word ] | join (" ")) ) // "Wot no number 1?",
  ( .[] | select(.numeral == 2) | ( [ "The", .ordinal, "word is", .word ] | join (" ")) ) // "Wot no number 2?",
  ( .[] | select(.numeral == 3) | ( [ "The", .ordinal, "word is", .word ] | join (" ")) ) // "Wot no number 3?",
  ( .[] | select(.numeral == 4) | ( [ "The", .ordinal, "word is", .word ] | join (" ")) ) // "Wot no number 4?",
  ( .[] | select(.numeral == 5) | ( [ "The", .ordinal, "word is", .word ] | join (" ")) ) // "Wot no number 5?"
]

它以某种方式产生可用的输出:

richard@sophia:~$ jq -f make-array.jq < numbers.json
[
  "The 1st word is One",
  "The 2nd word is Two",
  "Wot no number 3?",
  "Wot no number 4?",
  "The 5th word is Five"
]
richard@sophia:~$ 

然而，虽然它产生输出，处理丢失的元素并忽略我不想要的位，但它显然是非常无用的代码，需要 for 循环或类似的东西，但我看不到办法JQ来做这个。有什么想法吗？

Answer 1

jq解决方案:

jq 'def print(o): "The \(o.ordinal) word is \(o.word)";
    .numbers | (reduce map(select(.numeral))[] as $o ({}; .["\($o.numeral)"] = $o)) as $o
    | [range(0; ($o | [keys[] | tonumber] | max)) 
       | "\(.+1)" as $i
       | if ($o[$i]) then print($o[$i]) else "Wot no number \($i)?" end
    ]' input.json

输出:

[
  "The 1st word is One",
  "The 2nd word is Two",
  "Wot no number 3?",
  "Wot no number 4?",
  "The 5th word is Five"
]