Delete empty attributes in NiFi - apache-nifi

Question

Because of this issue being still unresolved, I have an EvaluateJsonPath processor that sometimes outputs attributes with empty strings.
Is there a straight-forward way to delete attributes from a flowfile?
I tried using the UpdateAttributes processor, but it only is able to delete based on matching an attribute's name (I need to match on the attribute's value).

Answer 1

you can use ExecuteGroovyScript 1.5.0 processor with the following code:
def ff=session.get()
if(!ff)return
def emptyKeys = ff.getAttributes().findAll{it.value==null || it.value==''}.collect{it.key}
ff.removeAllAttributes(emptyKeys)
REL_SUCCESS<<ff

Answer 2

After EvaluateJsonPath processor use RouteonAttribute processor and check the attributes having isEmpty values in them using Expression Language
Routeonattribute configs:-
Add new property
emptyattribute
${anyAttribute("id","age"):isEmpty()}
by using or funtion
${id:isEmpty():or(${age:isEmpty()})}
in the above expression language we are checking any id, age attribute having empty values for them and routing them to emptyattribute relation.
${allAttributes("id","age"):isEmpty()}
By using and function
${id:isEmpty():and(${age:isEmpty()})}
this expression routes only when both id,age attributes are empty.
Use Empty Relationship and connect that to Update Attribute processor and delete the attributes that you want to delete.
UpdateAttributeConfigs:-
in delete attribute expression mentioned id,age attributes need to delete.
By using RouteonAttribute after evaljsonpath processor we can check the required attributes are having values or not, then by using updateattribute we can delete the attributes that having empty values.

Answer 3

You can use a jolt transform, but i can only get it to work for fields at the top level of the json. Any nested fields are lost, although perhaps some real jolt expert can improve on the solution to stop that happening.
[
{
"operation": "shift",
"spec": {
"*": {
"": "TRASH",
"*": {
"$": "&2"
}
}
}
},
{
"operation": "remove",
"spec": {
"TRASH": ""
}
}
]

Answer 4

once you validate the required attribute values having empty strings, then make use of UpdateAttribute Advanced Usage and check the required attribute values having empty strings, then change the value to null.For Advance usage of Update attribute refer to this link community.hortonworks.com/questions/141774/… Add Rule: idnull Conditions:- ${id:isEmpty():or(${id:isNull()})} Actions:- id(attribute) null(value) – Shu Feb 3 '18 at 3:08
The approach does not remove attribute but just set the attribute value as null.