I have use case where I am trying to merge content using the NIFI MergeContent processor.
Scenario is that I am retrieving image files from a server, base64 encoding them and then batching them together into a JSON format using MergeContent. I am using the Header, Footer and Demarcator fields to constuct a JSON object array: [... { "id": <id value> "base64":<base64value> from merged flow file } .. ] Using the the NIFI expression language I was hoping to reference an attribute on the incoming files to populate the "id" field, and have it unique. All works well except my "id" files are the same for all the merged files. By using the expression language it appears the attribute value from only one of the files is being evaluated. Example of my expression language: "},{"recordid":${RecordID:trim()},"base64Image": Any advice would be helpful. Thanks in advance. Chris -- Chris Mangold 301-471-5758 (c) 301-898-7979 (h)