DataWeave programming challenge #7: Modify certain values from a JSON structure

Alex Martinez
Jun 13, 2023
2 min read

Updated: Aug 31, 2023

Other posts from this series:

DataWeave programming challenge #1: Add numbers separated by paragraphs and get the max number
DataWeave programming challenge #2: Rock Paper Scissors game score system
DataWeave programming challenge #3: Count palindrome phrases using the Strings module
DataWeave programming challenge #4: Solve the Tower of Hanoi mathematical puzzle
DataWeave programming challenge #5: Reverse a phrase's words, but keep the punctuation
DataWeave programming challenge #6: Using tail-recursion to get the factorial of a number
DataWeave programming challenge #7: Modify certain values from a JSON structure
DataWeave programming challenge #8: Sum all digits to get a 1-digit number

In this post:

Input
Explanation of the problem
Expected output
Clues
Answer

Try to solve this challenge on your own to maximize learning. We recommend you refer to the DataWeave documentation only. Try to avoid using Google or asking others so you can learn on your own and become a DataWeave expert!

💡 Tip: Instead of trying to write the whole code yourself, browse in the documentation for any function that would do the work for you 👀

Solve on the Playground

Input

Consider the following JSON input payload:

{
    "name": "a",
    "object": {
      "name": "b",
      "l": [
        {
          "other": "c",
          "list": [
            
          ]
        },
        {
          "thisname": "def",
          "list": [
            {
              "this": "500e",
              "l": [
                {
                  "finalname": "f"
                },
                {
                  "finalname": "ghijk"
                }
              ]
            }
          ]
        }
      ]
    },
    "array": [
      {
        "thisname": "h"
      },
      {
        "xyz": "abc123"
      }
    ]
  }

Explanation of the problem

Create a DataWeave script that will update all the values to uppercase, except the ones in which the field equals thisname.

For example, the first field name with the value "a" has to be transformed to "A". However, the field thisname with the value of "def" should stay the same.

Expected output

In this case, the expected output would be:

{
  "name": "A",
  "object": {
    "name": "B",
    "l": [
      {
        "other": "C",
        "list": [
          
        ]
      },
      {
        "thisname": "def",
        "list": [
          {
            "this": "500E",
            "l": [
              {
                "finalname": "F"
              },
              {
                "finalname": "GHIJK"
              }
            ]
          }
        ]
      }
    ]
  },
  "array": [
    {
      "thisname": "h"
    },
    {
      "xyz": "ABC123"
    }
  ]
}

Clues

If you're stuck with your solution, feel free to check out some of these clues to give you ideas on how to solve it!

Clue #1

Check out the Tree module to see if any of those functions is useful for this case.

Clue #2

Check out the mapLeafValues function.

Clue #3

Use the upper function to transform the strings to uppercase.

Clue #4

Use path[-1].selector to retrieve the name of each value's field and compare it with a given string value.

Answer

If you haven't solved this challenge yet, we encourage you to keep trying! It's ok if it's taking longer than you thought. We all have to start somewhere ✨ Check out the clues and read the docs before giving up. You got this!! 💙

There are many ways to solve this challenge, but you can find here some solutions we are providing so you can compare your result with us.

Solution #1

%dw 2.0

import mapLeafValues from dw::util::Tree

output application/json

---

payload mapLeafValues ((value, path) ->

if (path[-1].selector == "thisname") value

else upper(value)

)

Solution #2

%dw 2.0