prependIfMissing

prependIfMissing(String, String): String

Prepends the prefix to the beginning of the string if the text does not already start with that prefix.

Introduced in DataWeave 2.2.0. Supported by Mule 4.2 and later.

Parameters

Name Description

Name	Description
`text`	The input string.
`prefix`	The text to use as prefix.

text

The input string.

prefix

The text to use as prefix.

Example

This example shows how prependIfMissing behaves with different inputs and sizes.

Source

%dw 2.0
import prependIfMissing from dw::core::Strings
output application/json
---
{
  "a": prependIfMissing(null, ""),
  "b": prependIfMissing("abc", ""),
  "c": prependIfMissing("", "xyz"),
  "d": prependIfMissing("abc", "xyz"),
  "e": prependIfMissing("xyzabc", "xyz")
}DataWeave

Output

{
  "a": null,
  "b": "abc",
  "c": "xyz",
  "d": "xyzabc",
  "e": "xyzabc"
}JSON

prependIfMissing(Null, String): Null

Helper function that enables prependIfMissing to work with a null value.