apache nifi - I have two Json payload. I want to merge them in a single Json object

Question

I have two payloads and want to merge them into single JSON object (streaming join). At few places people are suggesting to use AttributesToJSON, but as one of the JSON does not have fix set of attributes I guess that would not be possible.

First payload is

{  
   "title":"API-Actions Documentation",
   "title_link":"https://api.slack.com/",
   "author_name":"name",
   "author_link":"http://flickr.com/bobby/",
   "author_icon":"http://flickr.com/icons/bobby.jpg",
   "text":"Optional",
   "image_url":"http://my-website.com/path/to/image.jpg",
   "thumb_url":"http://example.com/path/to/thumb.png",
   "footer":null,
   "pretext":"@name",
   "color":"#7CD197"
}

And second one is,

{  
"fields":[  
  {  
     "title":"Priority",
     "value":"low",
     "short":"true"
  },
  {  
     "title":"Priority",
     "value":"medium",
     "short":"true"
  },
  {  
     "title":"Priority",
     "value":"high",
     "short":"true"
  },
  {  
     "title":"Priority",
     "value":"blocker",
     "short":"true"
  }
 ]
}

I want the output as

{   
"title":"API-Actions Documentation",
"title_link":"https://api.slack.com/",
"author_name":"name",
"author_link":"http://flickr.com/bobby/",
"author_icon":"http://flickr.com/icons/bobby.jpg",
"text":"Optional",
"image_url":"http://my-website.com/path/to/image.jpg",
"thumb_url":"http://example.com/path/to/thumb.png",
"footer":null,
"pretext":"@name",
"color":"#7CD197",
"fields":[  
  {  
     "title":"Priority",
     "value":"low",
     "short":"true"
  },
  {  
     "title":"Priority",
     "value":"medium",
     "short":"true"
  },
  {  
     "title":"Priority",
     "value":"high",
     "short":"true"
  },
  {  
     "title":"Priority",
     "value":"blocker",
     "short":"true"
    }
   ]
  }

Answer 1

Easy! Just use MergeContent and set the following configuration:

Merge Format: Binary Concatenation
Minimum Number of Entries: 2
Delimiter Strategy: Text
Header: [
Footer: ]
Demarcator: ,

(You could use MergeRecord but it is a little buggy for me at least).

Then transfer to JoltTrasnformJSON and set Jolt Transformation DSL to Shift and Jolt Specification to:

{
    "*": {
      "*": "&"
    }
}

This should do the job :)