In DataWeave we can use expressions in strings that will be evaluated and inserted into the string value. This is called string interpolation. The expression must be enclosed in parentheses where the first parenthesis is prefixed with a dollar sign: $(<expression>). The expression must return a string value or can be automatically coerced into a string value in order for it to work. The expression can also be a variable.

In the following example we use a variable, selector, the upper function and a calculation that returns a number that is coerced into a string:


%dw 2.0

var prefix = "Hi"

var user = { alias: "mrhaki", name: "Hubert Klein Ikkink"}

var count = 41

output text/plain
welcome $( also known as $(upper(user.alias)).
You're visitor $(count + 1)."


welcome Hubert Klein Ikkink also known as MRHAKI.
You're visitor 42.

Written with DataWeave 2.4.

DataWeave is a functional language designed by MuleSoft for transforming data structures defined in for example JSON, XML or CSV.