API - Change Response from server

[FrankColumbo]

Hello

I have looked at a similar titled post at Format server response on API call but it didn’t have the answers I was looking for.

I am creating an API on the KNIME server that will be called from different programs around my company e.g KNIME flow, a C# App, an Python App etc. One of the first thing I do is validate the input JSON which could look like this:

{
   "Parameters":
   {
      "ReferenceNumber": "123456";
      "Name":"Joe Blogs"
   },
   {
   "SomeData":
   {
      "stuff": "to be or not to be",
      "morestuff": "that is the question"
   },
   {
   "otherData":
   {
      "evenmorestuff":"whether 'tis nobler in the mind"
   }
}

If the ReferenceNumber is invalid I would like to send a response back a 411 status code with an error message of “ReferenceNumber is not valid”

If “otherData” is missing I would like to send a response back a 412 status code with an error message of “otherData is missing”

If the internal flow workings on the API fail (for example in a try catch) I would like to send a response back with a 500 number and a message.

Also I would like to strip out most, if not all, of the standard response body. example of the first part below

Is this possible?

Frank

[marvin.kickuth]

Hi Frank,

I’m afraid it isn’t possible to change or extend the response codes of our rest interface. However, you can influence the data a called workflow returns. Checkout our Workflow Invocation Guide, especially the external clients section: KNIME Workflow Invocation Guide

Kind regards
Marvin

[thor]

Actually, it is possible by using the Container Output (Raw HTTP) and Container Input (Raw HTTP) nodes in combination with GET/POST …/rest/v4/repository/{path}:raw-execution.

Side note: you should not abuse existing HTTP status codes. For example 411 means "Length required " and 412 is for “Precondition failed”. Both do have semantic meanings which don’t match your purpose.
Usually if the input sent by the client is not correct you either return a generic 400 or 422 (Unprocessable Content).