Friday 15 March 2024

How would you use the map function to transform an array of objects into another array of objects? in MuleSoft 141

 How would you use the map function to transform an array of objects into another array of objects? in MuleSoft

Here's how to effectively utilize the map function in MuleSoft 4 to transform an array of objects into another array of objects:


Imagine you have an array of employee objects with properties like name and department, and you want to create a new array with additional information like employeeId and a modified departmentName.


  1. DataWeave Transformation:
    DataWeave provides a concise and versatile approach for manipulating data using the map function.

%dw 2.0
// Sample employee array
var employees = [
  { name: "John Doe", department: "engineering" },
  { name: "Jane Doe", department: "sales" }

// Transform the array using map
output = employees map (employee) -> {
  // Add new properties and potentially modify existing ones
  employee merge {
    employeeId: uniqueId(),  // Generate a unique ID
    departmentName: employee.department ++ " Department"


  • The map function iterates through each object (employee) within the original employees array.

  • Inside the map function:

  • The merge operator combines the existing employee object with a new object containing:

  • employeeId: Generated using the uniqueId() function (assuming you need unique IDs).

  • departmentName: The original department value concatenated with " Department".

  • The resulting output array contains the transformed employee objects with additional properties.

Key Points:

  • The map function allows you to apply transformations to each element in the array.

  • You can access properties within the current object using the . notation (e.g., employee.department).

  • DataWeave offers various functions like merge, uniqueId(), and string manipulation operators for data modification.

Additional Considerations:

  • Conditional Transformations: You can incorporate conditional logic within the map function to selectively transform objects based on specific criteria.

  • Complex Transformations: For intricate data manipulation scenarios, DataWeave provides powerful features like filtering, sorting, and nested transformations.

Further Exploration:

Alternative (Less Recommended):

  1. MEL (Message Expression Language):
    While MEL offers basic functionality for iterating through arrays, it can become cumbersome for complex transformations. Here's an example:


<foreach collection="#[payload]" doc:name="Employee Loop">
  <set-payload expression="#[payload merge {
      employeeId: java.util.UUID.randomUUID().toString(),
      departmentName: payload.department ++ ' Department'
  }]" doc:name="Update Employee" />

Remember: DataWeave is generally preferred due to its readability, expressiveness, and ability to handle intricate data manipulation tasks effectively.

No comments:

Post a Comment

Note: only a member of this blog may post a comment.