Dataweave Transformation- How can I reduce a payload array when condition is met

I have this JSON payload:

[
    {
        "Id": "6812",
        "status": "Available",
        "expirationDate": "2024-04-30T13:00:00.000-07:00",
        "quantityOnHand": 6124
    },
    {
        "Id": "7491",
        "status": "Available",
        "expirationDate": "2024-06-29T13:00:00.000-07:00",
        "quantityOnHand": 864
    },
    {
        "NetsuiteId": "6569",
        "status": "Available",
        "expirationDate": "2100-12-12T13:00:00.000-07:00",
        "quantityOnHand": 3

    },
    {
        "Id": "6582",
        "status": "Available",
        "expirationDate": "2100-12-12T13:00:00.000-07:00",
        "quantityOnHand": 1
    }
]

I have a variable component that sets my order quantity. Basically what I want to do is return the payload items that will suffice the order quantity variable. So for example my vars.quantityOrder is 100, then my transform component will return :

{
        "Id": "6812",
        "status": "Available",
        "expirationDate": "2024-04-30T13:00:00.000-07:00",
        "quantityOnHand": 6124
    }

If it is 6500 , then it would return :

[
    {
        "Id": "6812",
        "status": "Available",
        "expirationDate": "2024-04-30T13:00:00.000-07:00",
        "quantityOnHand": 6124
    },
    {
        "Id": "7491",
        "status": "Available",
        "expirationDate": "2024-06-29T13:00:00.000-07:00",
        "quantityOnHand": 864
    }
]

And so on.

I am very new to DataWeave and I'm not sure how I can do this. I have written up something like:

%dw 2.0
output application/json

var quantityOrder = vars.quantityOrder 

var result = payload filter ((item, index) -> quantityOrder > 0) map ((item, index) -> {
    "Id": item.Id,
    "status": item.status,
    "expirationDate": item.expirationDate,
    "quantity": item.quantityOnHand - quantityOrder

})

---
result

However this gives me syntax errors. Would appreciate any guidance or input.

Solution

It is not clear what is the issue you are having but if you are trying to get the items from the input payload where quantityOnHand > quantityOrder then the condition of your filter is incorrect. I would change it to:

%dw 2.0
output application/json

var quantityOrder = 100

var result = payload 
    filter ((item, index) -> item.quantityOnHand > quantityOrder) 
    map ((item, index) -> 
        {
            "Id": item.Id,
            "status": item.status,
            "expirationDate": item.expirationDate,
            "quantity": item.quantityOnHand - quantityOrder
        }
    )
---
result

The output for your input payload is:

[
  {
    "Id": "6812",
    "status": "Available",
    "expirationDate": "2024-04-30T13:00:00.000-07:00",
    "quantity": 6024
  },
  {
    "Id": "7491",
    "status": "Available",
    "expirationDate": "2024-06-29T13:00:00.000-07:00",
    "quantity": 764
  }
]