Unable to transform a JSON Object into Array of objects using JOLT JSON library

Question

Input JSON that I have to transform is as follows :

{
  "Business": [
    {
      "Label": "Entertainment",
      "category": "Advert",
      "weight": "",
      "types": [
        "T1",
        "T2"
      ]
    },
    {
      "Label": "FMCG",
      "category": "Campaign",
      "weight": "",
      "types": [
        "T9",
        "T10"
      ]
    }
  ]
}

Expected Output :

{
  "Business": [
    {
      "Label": "Entertainment",
      "category": "Advert",
      "weight": "",
      "types": "T1"
    },
    {
      "Label": "Entertainment",
      "category": "Advert",
      "weight": "",
      "types": "T2"
    },
    {
      "Label": "FMCG",
      "category": "Campaign",
      "weight": "",
      "types": "T9"
    },
    {
      "Label": "FMCG",
      "category": "Campaign",
      "weight": "",
      "types": "T10"
    }
  ]
}

I have tried the different JsonSpecs provided at the JOLT github help page. But I am not able to solve this. Any help or pointers will be appreciated.

is typess a typo in your input/output samples?

JAAulde
– JAAulde

2016-09-13 04:20:25 +00:00
Commented Sep 13, 2016 at 4:20 — JAAulde
– JAAulde, Commented Sep 13, 2016 at 4:20
Yes, it was typo. I have corrected it now.

abb
– abb

2016-09-13 04:35:15 +00:00
Commented Sep 13, 2016 at 4:35 — abb
– abb, Commented Sep 13, 2016 at 4:35

Milo S · Accepted Answer · 2016-09-13 15:08:10Z

8

You have to do two shift operations.

You want to "duplicate" the Label and Category based on how many entries you have in "types" array. So do that first, into a temporary "bizArray".

Also record which "type" goes with that duplicated Label and Category in a temporary "typeArray", that has the same indexes as the bizArray.

In the second shift, "join" the two parallel arrays, "bizArray" and "typesArray" to get your final array.

Spec

[
  {
    "operation": "shift",
    "spec": {
      "Business": {
        "*": { // business array
          "types": {
            "*": { // type array
              "@2": "bizArray[]",  // make a copy of the whole biz object
              "@": "typesArray[]"
            }
          }
        }
      }
    }
  },
  {
    "operation": "shift",
    "spec": {
      "bizArray": {
        "*": { // bizArray index
          "Label": "Business[&1].Label",
          "category": "Business[&1].category",
          "weight": "Business[&1].weight"
        }
      },
      "typesArray": {
        "*": "Business[&].types"
      }
    }
  }
]

answered Sep 13, 2016 at 15:08

Milo S

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3 Comments

abb Over a year ago

Thanks Milo, this works !. But I am not able to understand how this works. Documentation on this library is so convoluted that it makes no sense to me. I think I should try for another library.

JAAulde Over a year ago

Nice job! I've never used Jolt, but I took a look at this last night and spent a couple of hours reading the docs and playing around with the demo. I got really close (I knew it needed two shifts) but just couldn't get a correct final product. Jolt is interesting, to say the least!

Milo S Over a year ago

Thanks. It is a complex thing to doc. A) each operation (on purpose) can have a different DSL, as that is the whole point. Namely that a single DSL to rule them all is basically just Java. B) its recursive, and all operations operate one field at a time. Thus "aggregate" things and dealing with Arrays is "hard" / "obtuse".

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