Add attribute (String value) to an array in flow file.

[#1]

HI,

I have an attribute of type string and my flow file has an array of strings. I want to add attribute into the array of strings in flow file.

Please help me with the process.

Thank you

[#2]

@janapati10 

For me your question is to abstract, sorry. Could you show some of your data?

Are we talking about JSON-array?
If so and you are already using NiFi 1.10.0 there are some new options in expression language to manipulate JSON.

[#3]

This is my JSON in flow file content

{
"linkedData" : [ ],
"comid" : "C3XXXXXXXXXXA-aidan-16802451"
}

I have an attribute 

callid : C3XXXXXXXXXX-XXXX-16802451

I want attribute callid value into linkedData array in JSON of flow file

[#4]

Maybe you want to try this way. Worked on 1.10.0

[#5]

Thank so much for the reply.

I tried the flow, but i am see an exception "Unexpected token 'jsonPathAdd'". I am using nifi 2.11.

org.apache.nifi.processor.exception.ProcessException: Unable to evaluate new value for attribute 'FF_CONTENT': org.apache.nifi.attribute.expression.language.exception.AttributeExpressionLanguageException: Invalid Expression: ${FF_CONTENT:jsonPathAdd('$linkedData',${callid})} due to Unexpected token 'jsonPathAdd' at line 1, column 13.

[#6]

NiFi 2.11 ? I must have missed something...

Let's assume it is 1.11.0 then the used function should be available.

I think there is a typo in your Expression Language.

${FF_CONTENT:jsonPathAdd('$.linkedData', ${callid})}

There has to be a dot between $ and linkedData.

[#7]

Apologies I gave wrong version.nifi 1.9.2

Also I tried correcting syntax

Invalid Expression: ${FF_CONTENT:jsonPathAdd('$.linkedData',${callid})} due to Unexpected token 'jsonPathAdd'

[#8]

@janapati10 
Oh, too bad, this options for manipulating JSON with Expression Language are - as far as I know - not available before 1.10.0.

When the JSON-format is really stabil maybe this will work for you.

UpdateAttribute ==> ${FF_CONTENT:substringBefore('['):append('["'):append(${callid}):append('"]'):append(${FF_CONTENT:substringAfter(']')})}

It is not "elegant" but I haven't got another idea, sorry.