Arrays (dw::core::Arrays)

Arrays (dw::core::Arrays)

This module contains helper functions for working with arrays. In this tutorial will cover the most common DataWeave functions you will need to work with Arrays.

DataWeave 2.0 makes it easier to define an array with a range (“<start-index> to <end-index>”). The above expression will set the value from 1 to 15 ([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]) as an array for variable named “range”.

We will start with a brief review of filter, used to remove items from an Array based on some criteria.
We’ll then discuss map, which is used to transform every item in an Array into something else.
We’ll follow up with distinctBy, and groupBy, which can be used to eliminate duplicates in an Array and group like-kind items together, respectively.
We’ll finish with reduce. reduce is unlike the other functions because of how general-purpose it is.

Functions

Name	Description
countBy	Counts the elements in an array that return `true` when the matching function is applied to the value of each element.
divideBy	Breaks up an array into sub-arrays that contain the specified number of elements.
drop	Drops the first `n` elements. It returns the original array when `n <= 0` and an empty array when `n > sizeOf(array)`.
dropWhile	Drops elements from the array while the condition is met but stops the selection process when it reaches an element that fails to satisfy the condition.
every	Returns `true` if every element in the array matches the condition.
firstWith	Returns the first element that satisfies the condition, or returns `null` if no element meets the condition.
indexOf	Returns the index of the first occurrence of an element within the array. If the value is not found, the function returns `-1`.
indexWhere	Returns the index of the first occurrence of an element that matches a condition within the array. If no element matches the condition, the function returns `-1`.
join	Joins two arrays of objects by a given ID criteria.
leftJoin	Joins two arrays of objects by a given ID criteria.
outerJoin	Joins two array of objects by a given `ID` criteria.
partition	Separates the array into the elements that satisfy the condition from those that do not.
slice	Selects the interval of elements that satisfy the condition: `from <= indexOf(array) < until`
some	Returns `true` if at least one element in the array matches the specified condition.
splitAt	Splits an array into two at a given position.
splitWhere	Splits an array into two at the first position where the condition is met.
sumBy	Returns the sum of the values of the elements in an array.
take	Selects the first `n` elements. It returns an empty array when `n <= 0` and the original array when `n > sizeOf(array)`.
takeWhile	Selects elements from the array while the condition is met but stops the selection process when it reaches an element that fails to satisfy the condition.