How to add a JSON body to POST request, using the Request connector ?

[trya2l]

Hi,

I'm trying to send a POST request with some data to an MLflow model endpoint and get back the response (I'm following the MLflow docs: Deploy MLflow Model as a Local Inference Server).

The problem is, I don't know how to properly configure a POST request in ThingsBoard Gateway's Request connector. The docs only show examples for GET requests, like this one in request.json:

{
  "url": "getdata",
  "httpMethod": "GET",
  "httpHeaders": {
    "ACCEPT": "application/json"
  },
  "content": {
    "name": "morpheus",
    "job": "leader"
  }
}

If I try with content, I get a 500 error, which I guess means the payload is ignored.

{
  "url": "invocations",
  "httpMethod": "POST",
  "httpHeaders": {
    "ACCEPT": "application/json"
  },
  "contents": {
    "inputs": [
      [
        -0.955945000492777,
        -0.34598177569938643,
        -0.4635959746460942,
        0.4814814737734622
      ]
    ]
}

INFO:     10.88.0.2:60154 - "POST /invocations HTTP/1.1" 500 Internal Server Error

I looked at the code and found a reference to a data parameter, but I can't confirm if it works.

Because when I change content for data to send data in a POST request, the endpoint returns a 415 Unsupported Media Type error.

{
  "url": "invocations",
  "httpMethod": "POST",
  "httpHeaders": {
    "ACCEPT": "application/json"
  },
  "data": {
    "inputs": [
      [
        -0.955945000492777,
        -0.34598177569938643,
        -0.4635959746460942,
        0.4814814737734622
      ]
    ]
}

INFO:     10.88.0.2:39104 - "POST /invocations HTTP/1.1" 415 Unsupported Media Type

Has anyone successfully configured a POST request with JSON payload using the Request connector? Any example, config or tips on how to set the payload properly would be super helpful. The docs is a bit vague about that: Request Connector Configuration

Thanks!

[imbeacon]

Hi @trya2l,

Here is an example of RPC configuration for POST request:

    {
      "deviceNameFilter": ".*",
      "methodFilter": "post_test",
      "requestUrlExpression": "/",
      "responseTimeout": 1,
      "httpMethod": "POST",
      "requestValueExpression": "${params}",
      "responseValueExpression": "${message}",
      "timeout": 0.5,
      "tries": 3,
      "httpHeaders": {
        "Content-Type": "application/json"
      }
    },

Data from params from request will be send as body to the server, message field from response will be parsed and returned as a result.

Server respond to the request with the following body:

{
  "message": "Hello World"
}

Request sending:

Probably in your case, you just need change ACCEPT to Content-Type in httpHeaders.

[trya2l]

Hello @imbeacon ,

Thanks for the reply. You were right, I needed to change ACCEPT to Content-Type.