How to extract more than one field from json in Nifi? - apache-nifi

Question

I have JSON payload like this;
{
"id": "",
"name": "",
"A": {...},
"B": {...},
"C": {...}
}
And I want to extract A, B and C fields with id and name field as different record. Like this;
{
"id": "",
"name": "",
"A": {...}
}
{
"id": "",
"name": "",
"B": {...}
}
{
"id": "",
"name": "",
"C": {...}
}
I'm using record based processors. But I don't know that how can I do this in Nifi using record based processors.

Answer 1

The "EvaluateJsonPath" is probably what you're looking for. You can add JSONPath expressions, that will be converted to attributes, or written to the flowfile.
http://jsonpath.com/ is a handy web tool to test your expressions.

Answer 2

If you want to use record based processors, then JoltTransformRecord would do the trick. Just set Jolt Transformation DSL as Chain and Jolt Specification as:
[
{
"operation": "shift",
"spec": {
"id": "id",
"name": "name",
"*": {
"#": "array.&"
}
}
},
{
"operation": "shift",
"spec": {
"array": {
"*": {
"#(2,id)": "[#2].id",
"#(2,name)": "[#2].name",
"#": "[#2].&"
}
}
}
}
]
This will first put your unique elements in an array and separate the common keys from them, then it will put the common keys in all of the elements while extracting the array to a top array.
Then, if you want them as different FlowFiles too, you can SplitRecord the array and you got it!