How to define the JSON structure for any incoming flow file in Nifi

Question

I need to define the structure of JSON for all my incoming flow files. I have a JSON which is like this,

[
  {
    "user": "Tony",
    "dept": "Sales",
    "os": "linux"
  },
  {
    "user": "Smith",
    "os": "Windows",
    "dept": "Accounts"
  }
]

I want all my files of JSON to have a uniform structure sorted, eg. in the input my field positions are different for first object and second object. In the input the order we see is

{ "user" , "dept" , "os" } , { "user", "os", "dept" } 

I want my output to be

{ "user" , "dept" , "os" },  { "user" , "dept", "os" }

Need help doing this in Nifi

Answer 1

You can use a shift transformation spec by individually writing each attribute in order to sort them as desired such as

[
  {
    "operation": "shift",
    "spec": {
      "*": {
        "user|dept|os": "[&1].&"
      }
    }
  }
]

the demo on the site http://jolt-demo.appspot.com/ is