Range selector

Exercise

Given the following input payload:

[
    1,
    2,
    3,
    4,
    5,
    6,
    7,
    8,
    9,
    10
]

Write a DataWeave transformation that produces the following output:

[
    5,
    4,
    3,
    2,
    1
]

Hints

• To get this result you have to use the range selector [<n> to <n2>], where n and n2 are indexes.
• Remember that to reverse the list you can use negative indexes.

---

🔒🔓Show solution

%dw 2.0
output application/json
---
payload[0 to 4][-1 to 0]
// o payload[-6 to 0]

Notes:

1. The first thing we might think of is getting the range we want first, in this case from 1 to 5. For that we use the range selector to get those values by their indexes [0 to 4]. Once we have the range we were after, we simply flip the order of the list using negative indexes [-1 to 0]
2. Another solution would be to build the range directly with a negative index, looking for the index where the 5 sits. In this case [-6 to 0]