Dataweave Tricks: Extract Keys and Values From HashMap

Introduction

I have a requirement to extract the keys and values from a dataset like the following:

{
  "account1" : {
      "accountID" : "1234",
      "name" : "Mary Loo",
      "balance" : 234.32
     },
  "account2" : {
      "accountID" : "1234",
      "name" : "Lauren Flor",
      "balance" : 234.32
     },
  "account3" : {
      "accountID" : "1234",
      "name" : "Mary Loo",
      "balance" : 234.32
     }         
}

Apparently, the above data is a Map. Now we need to produce two dataset of values and keys from the input (Map) as the following:

[
    {
        "accountID": "1234",
        "name": "Mary Loo",
        "balance": 234.32
    },
    {
        "accountID": "1234",
        "name": "Lauren Flor",
        "balance": 234.32
    },
    {
        "accountID": "1234",
        "name": "Mary Loo",
        "balance": 234.32
    }
]

and

[
    "account1",
    "account2",
    "account3"
]

Understanding Dataweave pluck Function

Dataweave has devised a function particularly for this kind of requirement. Here is the solution to extract values of a HashMap

%dw 2.0
output application/json
---
payload pluck (item, key, index) -> item

The shorthand version:

%dw 2.0
output application/json
---
payload pluck $

And to extract the keys:

%dw 2.0
output application/json
---
payload pluck (item, key, index) -> key

The shorthand version:

%dw 2.0
output application/json
---
payload pluck $$