HTTP binding - set payload/body

I have a post request which is working fine in postman and even in a rule with sendHttpPostRequest

val url = "https://api.solarmanpv.com/device/v1.0/currentData?language=en"
val token = "oxoxoxoxox"  
val content = '{"deviceSn": "serialnr"}'
val headers = newHashMap("Authorization" -> "Bearer " + token)
var String request = sendHttpPostRequest(url, "application/json", content, headers, 3000)

Now I’m trying to convert this to the http bindng, but I don’t understand where I need to put the content part. (this is the same as body or payload, correct?)
Do I need to put this in the stateContent param in the channel?
If I don’t fill in this param I get

2021-12-22 01:24:19.451 [WARN ] [p.internal.http.HttpResponseListener] - Requesting 'https://api.solarmanpv.com/device/v1.0/currentData?language=en' (method='POST', content='null') failed: 500 null

and when I enter my content value, I also get a 500 error

2021-12-22 01:25:23.974 [WARN ] [p.internal.http.HttpResponseListener] - Requesting 'https://api.solarmanpv.com/device/v1.0/currentData?language=en' (method='POST', content='org.eclipse.jetty.client.util.StringContentProvider@75c2a206') failed: 500 null

Full thing

UID: http:url:solarman_currentData
label: Solarman currentData
thingTypeUID: http:url
configuration:
  authMode: BASIC
  headers:
    - Authorization = Bearer oxoxoxoxox
  ignoreSSLErrors: false
  baseURL: https://api.solarmanpv.com/device/v1.0/currentData?language=en
  delay: 0
  stateMethod: POST
  refresh: 30
  commandMethod: GET
  contentType: application/json
  timeout: 3000
  bufferSize: 2048
channels:
  - id: SOC_BAP1
    channelTypeUID: http:string
    label: SoC- Battery Pack 1
    description: ""
    configuration:
      stateContent: "deviceSn=serialnr"

What am I missing?

This is usually used to set up a periodic retrieval of data from some remote service, i.e. to update an OH Item’s state.
It’s not like your on-demand sendHttpPostRequest,

is related to you sending a command to an OH ltem, which triggers the HTTP sending.

You might look here -

So are you saying I can’t use the http binding for this purpose?

What does org.eclipse.jetty.client.util.StringContentProvider@3dd04500 actually mean?

No.
What exactly is your purpose, sending a POST when you command an Item? (Having to guess because you didn’t tell us when your rule version runs.)
Then you do not want any stateMethod or refresh, but do need to fix commandMethod

It’s the unique identity of the little job the binding runs to carry out the requested tasks. In this case I think that’s the “every 30 seconds POST” that you set up.

This post request is actualy grabbing data from my solarpanel cloud. So I wanted to trigger this every 5 minutes (now setup every 30s indeed). This post request returns a json offcourse which I wanted to transform into some items.

I already changed commandMethod to POST, but same message.

And to be clear, everything works in a rule, but I thought the HTTP binding is more suiteable for this.

Okay, I did not understand that at all.
Maybe all you need to do is send valid JSON with your request

Needs some quotes in the payload
"\"deviceSn\"=\"serialnr\""

Tried al kind of possibilities, but can’t figure it out. Will stick with my rule or use another approach