how to send dictionary in invoke http processor

[#1]

hi everyone ,

We want to put data in web app using API endpoint 

https://localhost:8000/api/event/${id}/attributes this is the API endpoint that i have used in invoke HTTP processor in Remote URL field with PUT method. 

we want to create new attribute with value and this attribute is a dictionary type so we have to pass the data in the dictionary format for this we have used updateattribute processor and attributetojson processor. 

updateAttribute processor snap

Attributetojson processor snap

and the below is out of attributetoJson processor (flowfile)

{"note":"note from nifi","attributes":"{\n \"workflow\":\"process\"\n }","id":"1ecfbcbb-38bf-49e9-a77e-a88w"}

the error msg in invoke http processor 

{ "code": 500, "errors": [ "Traceback (most recent call last):\n File \"/usr/local/lib/python3.6/site-packages/flask/app.py\", line 1949, in full_dispatch_request\n rv = self.dispatch_request()\n File \"/usr/local/lib/python3.6/site-packages/

No value set

as per my knowledge this is type error. I think the Dictionary is not sending in correct format . i have also used ${attributes:unescapeJson()} in updateAttribute ...but i think i have made a mistake in the declaration

property_name	property_value
attributes	{"workflow": "process"}
'attributes'	${attributes:unescapeJson()}

 thanks 

[#2 · Accepted solution]

@renuu You have to build the final values you want as separate key value pairs like this:

UpdateAttribute

Next you will use these attributes  to create a json object attribute using AttributesToJson:

AttributesToJson flowfile-attribute

After that, if you inspect the flowfile you will see the json object as JSONAttributes:

FlowFile Attribute JSONAttributes

From here you can use it as ${JSONAttributes} or if you need it to be called ${attributes} you just use another UpdateAttribute: