The filter Function (and Function Type Signatures) In DataWeave Mule 4

Filter

This function can be applied to an array. It iterates the array and matches the values with the expression. The output of the filter function is an array with the matching values.

The expression must return true or false. If the expression returns true for a value or index in the array, the value gets captured in the output array. If it returns false for a value or index in the array, that item gets filtered out of the output. If there are no matches, the output array will be empty.

The lambda takes in two arguments, a single item of type Any, and a index of type Number. It returns a Boolean. We can use a syntax that is very close to DataWeave to define this:

filter<T>(@StreamCapable items: Array<T>, criteria: (item: T, index: Number) -> Boolean): Array<T>

filter(Array<Any&gt;, ((Any, Number) -&gt; Boolean)) : Array<Any&gt;

Examples:

Input Payload:

{
  "Id": "1184001100000000517",
  "marketCode": "US",
  "languageCode": "en-US",
  "profile": {
  "base": {
     "username": "TheMule",
     "activeInd": "R",
     "phone": [
       {
          "activeInd": "Y",
          "type": "mobile",
          "primaryInd": "Y",
          "number": "230678123"
       },
       {
         "activeInd": "N",
         "type": "mobile",
         "primaryInd": "N",
         "number": ""
       },
       {
          "activeInd": "Y",
          "type": "mobile",
          "primaryInd": "Y",
          "number": "154896523"
       }

      ]
    }
  }
 }

Dataweave Script:

%dw 2.0
output application/json
---
{
    id: payload.Id,
    markCode: payload.marketCode,
    languageCode: payload.languageCode,
    username: payload.profile.base.username,
    phoneNumber: (payload.profile.base.phone filter ($.activeInd == "Y" and $.primaryInd== "Y")).number default []
}

Output Payload:

{
  "id": "1184001100000000517",
  "markCode": "US",
  "languageCode": "en-US",
  "username": "TheMule",
  "phoneNumber": [
    "230678123"
    "154896523"
  ]
}