Filter Selectors (myKey[?($ == “aValue”)])

myKey[?($ == “aValue”)] returns only the values of matching keys within an array or object. Note that ? is also used in Key Present Validator. If no key-value pairs match, the result is null.

The following example inputs the array of name keys returned by *.name, then checks for name keys with the value “Mariano”. It filters out any values that do not match. Note that the $ references the value of the selected key.

DataWeave Script:

%dw 2.0

output application/json

—

{ users: payload.users.*name[?($ == “Mariano”)] }

Input XML Payload:

<users>

  <name>Mariano</name>

  <name>Luis</name>

  <name>Mariano</name>

</users>

Output JSON:

{

  “users”: [

    “Mariano”,

    “Mariano”

  ]

}

The following example assumes the same input and returns all the key-value pairs of the input because the expression ( 1 == 1 ) is true. Note that a false expression, such as ( 1 == 2 ), returns null.

DataWeave Script:

%dw 2.0

output application/json

—

{ users: payload.users.*name[?( 1 == 1)] }

Input XML Payload:

<users>

  <name>Mariano</name>

  <name>Luis</name>

  <name>Mariano</name>

</users>

Output JSON:

{

  “users”: [

    “Mariano”,

    “Luis”,

    “Mariano”

  ]

}

The following example assumes the same input. It uses mapObject to iterate over the entire input object and return matching key-value pairs, filtering out any pairs that do not match.

DataWeave Script:

%dw 2.0

output application/json

—

payload mapObject { ($$) : $[?($==”Mariano”)] }

Input XML Payload:

<users>

  <name>Mariano</name>

  <name>Luis</name>

  <name>Mariano</name>

</users>

Output JSON:

{

  “users”: {

    “name”: “Mariano”,

    “name”: “Mariano”

  }

}

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