How to Decode Base64 URL Encoded String

SYMPTOM

You are getting the below error from the Transform Message component when you are using fromBase64 function:

Unable to transform String to Base 64 Binary. Reason : `Illegal base64 character 5f`

166| base64String as Binary {base: "64"} as Binary
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Trace:
at dw::core::Binaries::fromBase64 (line: 166, column: 5)
at main::main (line: 5, column: 21)

CAUSE

SOLUTION

%dw 2.0
import fromBase64 from dw::core::Binaries
output text/plain
---
fromBase64(payload.message replace /_/ with ("/") replace /-/ with("+") replace /\./ with(" "))