Dynamic Evaluate In Mule 4

In this tutorial we will demonstrate how can we Select Dataweave(DWL file)dynamically using Dynamic Evaluate In Mule 4.

Dynamic evaluate is useful if you wanted to select the dataweave script dynamically out of multiple DWL files on the basis of some conditions passed at runtime.

Create a sample project in anypoint studio and configure the listener to trigger the request

Create 3 Different DWL’s file to select dynamically

Customer.DWL

%dw 2.0
output application/java
---
[
  {
    "FirstName": "Andy",
    "LastName": "Rose",
    "CustID":111,
    "CustAddressID":4566,
    "CustContactID":3454,
  },
  {
    "FirstName": "Grant",
    "LastName": "Flower",
    "CustID":678,
    "CustAddressID":4566,
    "CustContactID":3454,
  }
]

Employee.DWL

%dw 2.0
output application/java
---
[
  {
    "FirstName": "John",
    "LastName": "Mike",
    "EmpID":123,
    "EmpAddressID":4566,
    "EmpContactID":3454,
  },
  {
    "FirstName": "Eves",
    "LastName": "Andrew",
    "EmpID":234,
    "EmpAddressID":4566,
    "EmpContactID":3454,
  }
]

Default.DWL

%dw 2.0
output application/java 
---
{
  message: "Object not matched to select the data"
}

Create a Dataweave Transformation to select the file on some condition

%dw 2.0
output application/java
---
if(attributes.queryParams.object =="customer")
    readUrl('classpath://dwl/customer.dwl', 'text/plain')
else if(attributes.queryParams.object =="employee")
    readUrl('classpath://dwl/employee.dwl', 'text/plain')
else
    readUrl('classpath://dwl/default.dwl', 'text/plain')

configure the dynamic evaluate, pass the expression as variable used to select the dwl file

Transform the payload

%dw 2.0
output application/json
---
payload

Deploy the application on local and test with different conditions

Test with employee as Query Parameter

Test with customer as Query Parameter

Test with queryparamter as employee1 which does not match any condition and default.dwl will be invoked

Sample Project: dynamicevaluate sample application