question Re: Processor doesn't read saved attribute in Support Questions

Processor doesn't read saved attribute

mizu — Tue, 12 Apr 2022 08:51:13 GMT

Hi,
I have a flow where I make an HTTP request, and I save as an attribute the last ID value with EvaluateJsonPath and ExtractText processors. However, the InvokeHTTP processor doesn't read the saved attribute. What should I change?

I attach an image of this part of the flow. Thank you very much in advance. I'm stuck at this point and I don't know what else to try.

Re: Processor doesn't read saved attribute

ckumar — Tue, 12 Apr 2022 14:04:52 GMT

trying to understand your flow pipeline with respect to your use case explanations, You have two upstream queued for InvokeHTTP , in one using ExtractText you are extracting text , which will be stored in flow file as an attribute then running HTTP Method from InvokeHTTP and configured Attributes to Send for the attributed which is created by ExtractText ?

What GenreateFlowFile os doing in this flow? what evaluation is configured with EvaluateJsonPath ?

Please provide more details

Re: Processor doesn't read saved attribute

ckumar — Tue, 12 Apr 2022 14:06:52 GMT

also, you mentioned "Processor doesn't read saved attribute" Which specific processor you are complaining about ?

Re: Processor doesn't read saved attribute

mizu — Sat, 16 Apr 2022 10:17:07 GMT

Thank you very much, ckmar, for your interest in my issue. I will provide you more details.

With InvokeHTTP, I make a request, which returns N rows in JSON format. To build this request I want to use the ID obtained in the previous request (separated by an interval of 5 minutes), because I need to get only new rows (with higher ID). To do this, with EvaluateJsonPath I get the highest ID, which I call last_entry_no, and with ExtractText I try to do the mapping to the attribute.

Therefore, what I need is that InvokeHTTP reads the attribute that I tried to assign in ExtractText.

Probably none of this is done this way, but I am starting with NiFi and I am trying all the options until I find a solution.

I added to the flow the GenerateFlowFile processor because I read somewhere that it was needed to start the flow, but it doesn't do any specific function.

I attach screenshots with the configuration of these processors. Thank you very much again.

InvokeHTTP:

EvaluateJSONPath:

ExtractText:

Re: Processor doesn't read saved attribute

mizu — Mon, 18 Apr 2022 13:23:44 GMT

I would need InvokeHTTP to read the attribute obtained from the previous request, done with the same processor. That was not a complaint, but desperation due to my incompetence. I guess that I am doing something wrong and that there will be a solution. Thank you again.