Thursday 2 May 2024

What’s the difference between apply and map functions in dataweave?356

 What’s the difference between apply and map functions in dataweave?

In DataWeave, both apply and map functions are used for data manipulation, but they cater to different scenarios. Here's a breakdown of their key differences:

1. map Function:

  • Purpose: Iterates over an array and applies a transformation to each element.

  • Syntax: map(array, transformationFunction)

  • Output: Returns a new array containing the transformed elements.

  • Use Cases:

  • Transforming each element in an array to a new format (e.g., converting numbers to strings, manipulating object properties).

  • Filtering an array based on a condition within the transformation function.

  • Example:

%dw 2.0
input: [1, 2, 3]
output: map(input, (value) => value * 2) // Multiplies each element by 2

// Output: [2, 4, 6]

2. apply Function:

  • Purpose: Applies a function to a single value or object.

  • Syntax: apply(function, value)

  • Output: Returns the result of the function applied to the provided value.

  • Use Cases:

  • Calling a custom function defined elsewhere in your DataWeave script.

  • Performing a specific operation on a single value.

  • Example:

%dw 2.0
var doubleIt = (value) => value * 2;
input: 5
output: apply(doubleIt, input) // Calls the doubleIt function with the value 5

// Output: 10

Key Differences Table:


map Function

apply Function


Iterates and transforms elements in an array

Applies a function to a single value or object


map(array, transformationFunction)

apply(function, value)



Single value or object


New array containing transformed elements

Result of the function applied to the value

Use Cases

Array manipulation, element-wise transformations

Custom function calls, single value operations

Choosing the Right Function:

  • Use map when you need to iterate over an array and transform each element based on a specific logic.

  • Use apply when you want to apply a pre-defined function to a single value or object.

In essence:

  • map is ideal for array processing and element-wise transformations.

  • apply is suited for applying custom functions or operations to single values or objects.

By understanding the distinct functionalities of map and apply, you can effectively manipulate data within your MuleSoft 4 integration flows using DataWeave.

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