Is this correct way to filter items from a list based on certain conditions in Jolt?

Recently, we came across a scenario in which we needed to filter some elements from the input JSON based on certain conditions.

We were wondering if this was possible in the Jolt.

After some exploration, we tried to change the existing Jolt spec, but it did not produce the expected output JSON.

To achieve the desired output JSON, we have used another shift operation to filter the input JSON, in combination with other operations.

Let’s make it more clear with an example.

Assume we’ve input JSON as shown below.

[
  {
    "productId": "10002",
    "shopifyProductId": "31675487486045",
    "shopifyInventoryItemId": "33346316861533",
    "isPreOrder": "N",
    "isBackOrder": "Y",
    "computedLastInventoryCount": 7956,
    "productStoreId": "SG_STORE"
  },
  {
    "productId": "10003",
    "shopifyProductId": "31675487486046",
    "shopifyInventoryItemId": "33346316861536",
    "isPreOrder": "N",
    "isBackOrder": "N",
    "computedLastInventoryCount": 7958,
    "productStoreId": "SG_STORE"
  }
]

On the basis of values of the attributes 'isPreOrder' = N and 'isBackOrder' = N we need to filter the input JSON

Expected Output

[ {
  "HC_PRODUCT_ID" : "10003",
  "INVENTORY_ITEM_ID" : "33346316861536",
  "PRODUCT_VARIANT_ID" : "31675487486046"
} ]

To get the expected output we need to use shift operation with some wildcards, as shown below

Jolt Spec

[
  {
    "operation": "shift",
    "spec": {
      "*": {
        "isPreOrder": {// check the attribute isPreOrder
          "N": {// if the value is N
            "@(2,isBackOrder)": {//go on the two level up check for the isBackOrder
              "N": {// if the value is N
                "@4": "[]"// go the four level up take the object and put it into the list
              }
            }
          }
        }
      }
    }
  },
  {
    "operation": "shift",
    "spec": {
      "*": {
        "productId": "[&1].HC_PRODUCT_ID",
        "shopifyInventoryItemId": "[&1].INVENTORY_ITEM_ID",
        "shopifyProductId": "[&1].PRODUCT_VARIANT_ID"
      }
    }
  }
]

First shift is to filter the list and second shift is to modify the attributes.

Please share your thoughts.

You can use the following which combines those two conditionals within a single shift transformatio spec

[
  {
    "operation": "shift",
    "spec": {
      "*": {
        "isPreOrder": {
          "N": {
            "@2,isBackOrder": {// traverse tree two levels to reach the level of the attribute within the input
              "N": {
                "@4,productId": "[#2].HC_PRODUCT_ID",
                "@4,shopifyInventoryItemId": "[#2].INVENTORY_ITEM_ID",
                "@4,shopifyProductId": "[#2].PRODUCT_VARIANT_ID"
              }
            }
          }
        }
      }
    }
  }
]

Another option uses prefixing by those attributes first, then filter out
by double N such as

[
  {
    "operation": "shift",
    "spec": {
      "*": {
        "*": "@1,isPreOrder.@1,isBackOrder.&"
      }
    }
  },
  {
    "operation": "shift",
    "spec": {
      "@N.N": {
        "productId": "[#].HC_PRODUCT_ID",
        "shopifyInventoryItemId": "[#].INVENTORY_ITEM_ID",
        "shopifyProductId": "[#].PRODUCT_VARIANT_ID"
      }
    }
  }
]