This post was originally published on: https://dzone.com/articles/mule-4-dataweave-functions-part-1

In DataWeave 2.0, functions are categorized into different modules:

1. Core (dw::Core)
2. Arrays (dw::core::Arrays)
3. Binaries (dw::core::Binaries)
4. Encryption (dw::Crypto)
5. Diff (dw::util::Diff)
6. Objects (dw::core::Objects)
7. Runtime (dw::Runtime)
8. Strings (dw::core::Strings)
9. System (dw::System)
10. URL (dw::core::URL)

Functions defined in Core (dw::Core) module are imported automatically into your DataWeave scripts. To use other modules, we need to import them by adding the import directive to the head of DataWeave script, for example:

import dw::core::Strings
import dasherize, underscore from dw::core::Strings
import * from dw::core::Strings

Sample Payload:

{
"firstName" : "Murali",
"lastName" : "Krishna",
"age" : "26",
"age" : "26"
}

1. Core (dw::Core)

Below are the DataWeave 2 core functions:

++ , –, abs, avg, ceil, contains, daysBetween, distinctBy, endsWith, filter, IsBlank, joinBy, min, max, etc.

• result : [0, 1, 2] ++ [“a”, “b”, “c”] will gives us “result” : “[0, 1, 2, “a”, “b”, “c”]”
• result : [0, 1, 1, 2] — [1,2] will gives us “result” : “[0]”
• result : abs(-20) will gives us “result” : 20
• average : avg([1, 1000]) will gives us “average” : 500.5
• value : ceil(1.5) will gives us “value” : 2
• result : payload contains “Krish” will gives us “result” : true
• days: daysBetween(“2016-10-01T23:57:59-03:00”, “2017-10-01T23:57:59-03:00”) will gives us “days”: 365
• age : payload distinctBy $ will gives us:

{
    "firstName" : "Murali",
    "lastName" : "Krishna",
    "age" : "26"
}

• a: “Murali” endsWith “li” will gives us “a” : true
• a: [1, 2, 3, 4, 5] filter($ > 2) will gives us “a” : [3,4,5]
• empty: isBlank(“”) will gives us “empty” : true
• aa: [“a”,”b”,”c”] joinBy “-” will gives us “a” : “a-b-c”
• a: min([1, 1000]) will gives us “a” : 1
• a: max([1, 1000]) will gives us “a” : 1000

2. Arrays (dw::core::Arrays)

Arrays related functions in DataWeave are:

• countBy, divideBy, every, some, sumBy
• [1, 2, 3] countBy (($ mod 2) == 0) will gives us 1
• [1,2,3,4,5] dw::core::Arrays::divideBy 2 will gives us:

[
  [
    1,
    2
  ],
  [
    3,
    4
  ],
  [
    5
  ]
]

• [1,2,3,4] dw::core::Arrays::every ($ == 1) will gives us “false”
• [1,2,3,4] dw::core::Arrays::some ($ == 1) will gives us “true”
• [ { a: 1 }, { a: 2 }, { a: 3 } ] sumBy $.a will gives us “6”

3. Binaries (dw::core::Binaries)

Binary functions in DataWeave-2 are:

• fromBase64, fromHex, toBase64, toHex
• toBase64(fromBase64(12463730)) will gives us “12463730”
• { “binary”: fromHex(‘4D756C65’)} will gives us “binary” : “Mule”
• { “hex” : toHex(‘Mule’) } will gives us “hex” : “4D756C65”

4. Encryption (dw::Crypto)

Encryption functions in Dataweave – 2 are:

• HMACBinary, HMACWith, MD5, SHA1, hashWith
• { “HMAC”: Crypto::HMACBinary((“aa” as Binary), (“aa” as Binary)) } will gives us :
• “HMAC”: “\u0007£š±]\u00adÛ\u0006‰\u0006Ôsv:ý\u000b\u0016çÜð”
• Crypto::MD5(“asd” as Binary) will gives us “7815696ecbf1c96e6894b779456d330e”
• Crypto::SHA1(“dsasd” as Binary) will gives us “2fa183839c954e6366c206367c9be5864e4f4a65”

5. Diff (dw::util::Diff)

It calculates the difference between two values and returns list of differences.

DataWeave Script:

%dw 2.0
import * from dw::util::Diff
output application/json
var a = { age: "Test" }
var b = { age: "Test2" }
---
 a diff b

Output:

{
  "matches": false,
  "diffs": [
    {
      "expected": "\"Test\"",
      "actual": "\"Test2\"",
      "path": "(root).age"
    }
 ]
}

Note:

We will proceed with the rest of the functions in the Mule 4 DataWeave Functions: Part 2 article.