How to keep a condition for null value in jolt?

Question

INPUT:

 { 
   "itemName": null,
   "itemNumber": 22
 }

OUTPUT:

 {
   "isItemNameNull": true,
   "itemNumber": 22
 }

I should not map the value if its null but map 'isItemNameNull' to true,

SPEC:

[
 {
"operation": "shift",
"spec": {
  "itemName": {
    "null": {
      "true": "isItemNameNull"
    },
    "": {
      "#TRASH": "TRASH"
    },
    "*": {
      "@(2,itemName)": "itemName"
    }
  },
  "itemNumber": {
    "null": {
      "#TRASH": "TRASH"
    },
    "": {
      "#TRASH": "TRASH"
    },
    "*": {
      "@(2,itemNumber)": "itemNumber"
    }
  }
  }
 }
]

I mapped the flag but it did'nt took it from null condition.Can any one please suggest me a help.Thanks.

score 2 · Answer 1 · answered Jun 03 '21 at 12:41

You can achieve this by a combination of default and shift operations.

First use a default to detect if itemName is null and assign it a default value of true

Then use a shift to process the itemName appropriately:

if itemName is true (i.e. was set in the default because its original value was null), then set isItemNameNull using the value of itemName
else copy itemName to the output (I've assumed that you want to do this, otherwise just leave this second bit out)

[
  {
    "operation": "default",
    "spec": {
      "itemName": true
    }
  },
  {
    "operation": "shift",
    "spec": {
      "*": "&",
      "itemName": {
        "true": {
          "@1": "isItemNameNull"
        },
        "*": {
          "@1": "itemName"
        }
      }
    }
  }
]

One caveat being that if the input has a string of "true" for itemName

{
  "itemName": "true",
  "itemNumber": 22
}

then the output will be

{
  "isItemNameNull": "true",
  "itemNumber": 22
}

So not foolproof!

To get around that pitfall you could use a 3 step approach:

if itemName is null assign it an appropriate default "marker" value
process itemName and if it has the "marker" value set isItemNameNull to String value "true"
convert isItemNameNull to a boolean

[
  {
    "operation": "default",
    "spec": {
      "itemName": "null_marker"
    }
  },
  {
    "operation": "shift",
    "spec": {
      "*": "&",
      "itemName": {
        "null_marker": {
          "#true" :"isItemNameNull"
        },
        "*": {
          "@1": "itemName"
        }
      }
    }
  },
  {
    "operation": "modify-overwrite-beta",
    "spec": {
      "isItemNameNull": "=toBoolean"
    }
  }
]

score 0 · Answer 2 · answered Feb 18 '20 at 14:29

I tried this case. I edited a little in your input json also.

Input Json
----------
{
  "itemName": "null",
  "itemNumber": 22
}


SPEC:
----
    [
      {
        "operation": "shift",
        "spec": {
          "itemName": {
            "null": {
              "#true": "isItemNameNull"
            }
          },
          "itemNumber": "itemNumber"
        }
       }
    ]

Output Json
-----------

{
  "isItemNameNull" : "true",
  "itemNumber" : 22
}

Try yourself please

score -1 · Answer 3 · answered Nov 26 '18 at 16:11

-1

There isn't a good way of doing that.

answered Nov 26 '18 at 16:11

Milo S

4,466
1
19
22

How to keep a condition for null value in jolt?

3 Answers3