DataWeave has a standard function to join array elements into a string value: joinBy in the dw::Core module. The joinBy function takes an array as first argument and a string value that is used as separator. The array should have string values or values that can be coerced into string values.

In the following example we use the function joinBy that will join elements in an array with a given separator:


%dw 2.0

output application/json
  // Join with default separator ("") using infix notation
  join: ["a", "b", "c"] joinBy "",

  // Join with ", " as separator
  separator: joinBy(["a", "b", "c"], ", "),

  // Elements can also be non-string values
  // if they can be coerced into string values
  range: [1, 2, 3, 4] joinBy "|"


  "join": "abc",
  "separator": "a, b, c",
  "range": "1|2|3|4"

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.