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3985 :: raw beginner json question

• luvnim (orginal) [2018-06-27T08:16:29+02:00] view original

  I have an array of json objects,

  var js:JsonNode = [{"mango":"green"},{"orange":"yellow"},{"peach":"red"},{"grape":"black"}]

  I want just the keys in js, ["mango", "orange", "peach", "grape"]

  What is an easy way to do this?

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• mashingan (orginal) [2018-06-27T09:29:06+02:00] view original

  using iterators, this is how you do it

  import json
  
  var js = parseJson"""
    [{"mango":"green"},{"orange":"yellow"},
    {"peach":"red"},{"grape":"black"}]"""
  
  var keys = newSeq[string]()
  for obj in js.items:
    for k,_ in obj.pairs:
      keys.add k
  
  echo keys
  Run

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• Tiberium (orginal) [2018-06-27T12:02:11+02:00] view original

  FYI: you can remove ".items" here and it will still work because items() proc can be used implicitly by for loop :)

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• luvnim (orginal) [2018-06-27T15:32:36+02:00] view original

  Thanks you @Tiberium. This is neat!

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• luvnim (orginal) [2018-06-27T15:36:56+02:00] view original

  Thank you @mashingan. To my mind a clean way that fits Nim's practical approach to getting things done.

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• dom96 (orginal) [2018-06-27T16:16:11+02:00] view original

  Please format your code blocks like described here: https://forum.nim-lang.org/about/rst

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• kaushalmodi (orginal) [2018-06-27T17:13:14+02:00] view original

  To add to that, the .pairs can be removed too :)

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• luvnim (orginal) [2018-06-27T18:01:31+02:00] view original

  Done. That was easy :-)

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• mashingan (orginal) [2018-06-27T18:50:36+02:00] view original

  @tiberium @kaushalmodi Thanks, I knew it works for openArray[T] but never knew that it works for JsonNode too.

  I guess we really need Iterable type then ;)

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• Tiberium (orginal) [2018-06-28T17:40:32+02:00] view original

  @mashingan it works for any type which has items defined:

  type
    MyObject = object
      something: int
  
  iterator items(m: MyObject): int =
    # Return `something` 10 times
    for x in 1..10:
      yield m.something
  
  let myobj = MyObject(something: 5)
  # Will echo "5" 10 times
  for x in myobj:
    echo x
  Run

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