Variables In Dataweave

There are different way of declaring and using the variables in dataweave.

• Global variables are initialized in the header of the DataWeave script and can be referenced by name from anywhere in the body of a DataWeave script.
• The header of a DataWeave script accepts a var directive that initializes a variable, for example: var string=’USA’. You can declare multiple global variables on separate lines in the header.
• Local variables are initialized in the body of the DW script and can be referenced by name only from within the scope of the expression where they are initialized.

Note: DW variables cannot be reassigned. They are also distinct from variables that are part of the Mule message (such as target variables). variables do not persist beyond the scope of the script in which they are initialized

Input:

{
  "id": "1",
  "employee_name": "John",
  "employee_salary": 320800,
  "employee_age": 61,
  "profile_image": ""
}

Global Dataweave Variable:

Dataweave Expression:

%dw 2.0
output application/json
var value = "Welcome"
---
{
  message: value ++ vars.name
}

Output:

{
  "message": "WelcomeJohn"
}

Local Dataweave Variable:

Dataweave Expression:

%dw 2.0
output application/json
---
{
  message: using(value = "Hello") value ++ payload.employee_name
}

Output:

{
  "message": "HelloJohn"
}