Move JSON properties up one level

[zmajeed]

Here's some ways I found with mlr 6.9 to move all properties of a JSON object up one level - the parent field is oldtop - its child properties need to move up to the level of oldtop - and oldtop should disappear

Input test.json

{
  "oldtop": {
    "child_0": {
      "child_00": {
        "child_000": "child_000 value",
        "child_001": 123
      },
      "child_01": [
        {
          "child_010": "child_010 value 0",
          "child_011": 231
        },
        {
          "child_010": "child_010 value 1",
          "child_011": 312
        }
      ]
    },
    "child_1": "child_1 value",
    "child_2": 987
  }
}

Output

{
  "child_0": {
    "child_00": {
      "child_000": "child_000 value",
      "child_001": 123
    },
    "child_01": [
      {
        "child_010": "child_010 value 0",
        "child_011": 231
      },
      {
        "child_010": "child_010 value 1",
        "child_011": 312
      }
    ]
  },
  "child_1": "child_1 value",
  "child_2": 987
}

These 3 methods work as long as properties of oldtop and root are unique

1. Use mapsum to combine two objects as maps - merge oldtop into the root object

mlr --from test.json --json --no-jlistwrap put '
  $* = mapsum($*, $oldtop)
  unset $oldtop
'

2. Use a for-loop to iterate over each property of oldtop and create a new property in root

mlr --from test.json --json --no-jlistwrap put '
  for(k, v in $oldtop) {
    $[k] = v
  }
  unset $oldtop
'

3. Flatten JSON and strip leading oldtop. from field names - finally unflatten

mlr --from test.json --json --no-jlistwrap flatten then rename -r "^oldtop\.," then unflatten

What if oldtop and root have common properties? None of these methods will work as-is

4. This modifies method 2 to check for shared properties and create a new merged object with the two different values as children

mlr --from test.json --json --no-jlistwrap put '
  for(k, v in $oldtop) {
    if(!haskey($*, k)) {
      $[k] = v
      continue
    }
    k_merged = k . "_merged"
    $[k_merged][k . "_oldtop"] = v
    $[k_merged][k . "_root"] = $[k]
    unset $[k]
  }
  unset $oldtop
'

Method 4 gives

{
  "child_0_merged": {
    "child_0_oldtop": {
      "child_00": {
        "child_000": "child_000 value",
        "child_001": 123
      },
      "child_01": [
        {
          "child_010": "child_010 value 0",
          "child_011": 231
        },
        {
          "child_010": "child_010 value 1",
          "child_011": 312
        }
      ]
    },
    "child_0_root": "child_0 top value"
  },
  "child_1": "child_1 value",
  "child_2": 987
}

[johnkerl]

@zmajeed This is nice!! 😎

[aborruso]

Thank you very much @zmajeed