How do we traverse a jolt spec?

Question

this is a simple question,I am new to nifi and jolt. I just wanted to know,how to travserse the jolt spec while using wild card characters.For example,this is an example in jolt demo site,

input is

{
  "data": {
    "1234": {
      "clientId": "12",
      "hidden": true
    },
    "1235": {
      "clientId": "35",
      "hidden": false
    }
  }
}

Spec is

[
  {
    "operation": "shift",
    "spec": {
      "data": {
        "*": {
          "hidden": {
            "true": {
              // if hidden is true, then write the value disabled to the RHS output path
              // Also @(3,clientId) means lookup the tree 3 levels, to the "1234" or "1235" level,
              //  and then come back down down the tree and grabe the value of "clientId"
              "#disabled": "clients.@(3,clientId)"
            },
            "false": {
              "#enabled": "clients.@(3,clientId)"
            }
          }
        }
      }
    }
  }
]

and output is

{
  "clients" : {
    "12" : "disabled",
    "35" : "enabled"
  }
}

How did we get the above output? like what @(3,clientsid).As far as I understand, it goes 3 levels up.But 3 levels with respect to what..the spec or the input? Either way,how to move 3 levels up,can you please define which are the levels here?

Thanks in advance

user_5841306 · Answer

Just count the number of each opening curly-braces({) or colons(:) in the backward direction. Whenever they're not independent such as :{, then count this as only one in order to reach to the target key which is "*" wildcard just under "data" key in this case, and for @(3,clientId); first level is crossing the colon(:) next to "#disabled" or "#enabled", second level is crossing opening curly-braces next to those boolean keys for each, and then the third level is crossing opening curly-brace just after "hidden" key to reach the indexes the object with the "data" key.

How do we traverse a jolt spec?

1 Answers