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pluck

pluck({ (K)?: V }, (value: V, key: K, index: Number) -> R): Array<R>

Useful for mapping an object into an array, pluck iterates over an object and returns an array of keys, values, or indices from the object.

It is an alternative to mapObject, which is similar but returns an object, instead of an array.

Parameters

Name Description

object

The object to map.

mapper

Expression or selector that provides the key, value, and/or index (optional) used for mapping the specified object into an array.

Example

This example iterates over { "a":"b","c":"d"} using the anonymous mapper function ((value,key,index) → { (index) : { (value):key} }) to invert each key-value pair in the specified object and to return their indices as keys. The mapper uses named parameters to identify the keys, values, and indices of the object. Note that you can write the same expression using anonymous parameters, like this: {"a":"b","c":"d"} pluck { ($$$) : { ($):$$} } Unlike the almost identical example that uses mapObject, pluck returns the output as an array.

Source

%dw 2.0
output application/json
---
{"a":"b","c":"d"} pluck (value,key,index) -> { (index) : { (value):key} }

Output

[ { "0": { "b": "a" } }, { "1": { "d": "c" } } ]

Example

This example uses pluck to iterate over each element within <prices/> and returns arrays of their keys, values, and indices. It uses anonymous parameters to capture them. Note that it uses as Number to convert the values to numbers. Otherwise, they would return as strings.

Source

%dw 2.0
output application/json
var readXml = read("<prices>
    <basic>9.99</basic>
    <premium>53.00</premium>
    <vip>398.99</vip>
    </prices>", "application/xml")
---
"result" : {
  "keys" : readXml.prices pluck($$),
  "values" : readXml.prices pluck($) as Number,
  "indices" : readXml.prices pluck($$$)
}

Output

{
   "result": {
     "keys": [ "basic", "premium", "vip" ],
     "values": [ 9.99, 53, 398.99 ],
     "indices": [ 0, 1, 2 ]
   }
}

pluck(Null, (value: Nothing, key: Nothing, index: Nothing) -> Any): Null

Helper function that enables pluck to work with a null value.