NiFi JoltTransformJSON 2.0.0 trasform JSON flowfile

[#1]

Hi Everyone,

Struggling with transforming the JSON flow file, would appreciate help from the community!

input json flow file:

[{
"firstName": "John",
"LastName": "Malkovich",
"MiddleName": "J",
"nameType": {
"type1": "Other"
"type2": "Primary"
}
}, {
"firstName": "Johnny",
"LastName": "Cage",
"MiddleName": "M",
"nameType": {
"type1": "Basic"
"type2": "Primary"
}
}
]

expected output json flow file:

{
"fileName": "file.xml",
"count": "2",
"individuals": [{
"firstName": "John",
"LastName": "Malkovich",
"MiddleName": "J",
"nameType": {
"type1": "Other"
"type2": "Primary"
}
}, {
"firstName": "Johnny",
"LastName": "Cage",
"MiddleName": "M",
"nameType": {
"type1": "Basic"
"type2": "Primary"
}
}
]​
}

Jolt  specification :
[ { "operation": "default", "spec": { "fileName": "file.xml"", "count": "=2" } }, { "operation": "shift", "spec": { "*": { "@": "individuals[]" } } } ]

gettingError:

TransformException: The Spec provided can not handle input that is a top level Json Array.

[#2 · Accepted solution]

Hi @FreddyM ,

It seems like the default spec doesnt like it when the root object is an array. The good news is that there are other ways to assign default values , for example in the shift spec using # on the left hand side allows you to set default as follows:

[
  {
    "operation": "shift",
    "spec": {
      "#file.xml": "fileName",
      "#2": "count",
      "*": {
        "@": "individuals[]"
      }
    }
	}
]

If you have the fileName and the count values stored in flow file attribute you can reference them using expression language as in :

"#${fileNameAttribute}":"fileName"

Hope that helps. Please accept solution if it does.

Thanks

[#3]

@SAMSAL  Solution worked like a charm, special thank you for additional hint on passing attribute to json payload. 
Thank you.