Signal K•6mo ago

Johnathan B - HiCould someone point me in the ...

Hi Could someone point me in the right direction please as I am now going around in circles. I'm trying to write some very basic Python code to post a value to a path. I ultimately want to port it to CircuitPython. I have code to get an auth token and post a path value successfully via steaming websockets running in Python, but there are some issue porting this to circuit python. I have therefore been trying to write code in Python (on a PC) using a straightforward PUT , but whatever I try and can not get it to work. I have separate code to successfully make and access request and return the device token (manually hard coded int his example below) . In this simple test example below I am returning code 401 "You do not have permission to view this resource, <a href='/admin/#/login'>Please Login</a>" Having spent most of the day on this trying many approaches I am clearly getting something fundamentally wrong. I would be grateful of any pointers - thank you. (


import requests

server_url = "http://192.168.2.133:3000"
# Token hard coded from previously authorized access request
api_token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJkZXZpY2UiOiJ5b3VyX2RldmljZV9pZCIsImlhdCI6MTcxMTQ2Nzg1N30.X2wxz-qzux0RWQyFq8zQ8v1La9jGBf9r1iL0xgjtliE"

path = "electrical/batteries/999/capacity/timeRemaining"

value = 120  

# Construct URL with path
url = f"{server_url}/signalk/v1/{path}"

# Set headers with API token
headers = {
    "Authorization": f"Bearer {api_token}",
    "Content-Type": "application/json",
}

# Data to send in PUT request
data = {"value": value}

try:
  # Send PUT request
  response = requests.put(url, headers=headers, json=data)

  # Check for successful response
  if response.status_code == 200:
    print("Value written successfully to Signal K path:", path)
  else:
    print(f"Error writing to Signal K path: {path}. Status code: {response.status_code}")
    print(response.text)

except requests.exceptions.RequestException as e:
  print(f"Error: {e}")

)

9 Replies

Roger•6mo ago

Your json data is probably formatted incorrectly. Signalk is probably expecting a delta update. http://signalk.org/2014/11/05/new-delta-format.html You can test with the data fiddler. http://[server-ip]:3000/admin/#/serverConfiguration/datafiddler

Johnathan B•6mo ago

Thanks for your help Roger I had tried the json previously. Here is the same code but no using the url /signalk/v1/api and some json that works fine in the data fiddler. Again I get this errror Error writing to Signal K path: api/. Status code: 401 You do not have permission to view this resource, <a href='/admin/#/login'>Please Login</a> Previously I have tried the same code but creating the token based on an u / p login - with the same issue. (


import requests

# Replace with your Signal K server URL and API token
server_url = "http://192.168.2.133:3000"
api_token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJkZXZpY2UiOiJ5b3VyX2RldmljZV9pZCIsImlhdCI6MTcxMTQ2Nzg1N30.X2wxz-qzux0RWQyFq8zQ8v1La9jGBf9r1iL0xgjtliE"

# Path to write to
path = "api/"   #----------------------Changed here 

# Value to write (replace with desired time remaining value)
value = 120  # Example value in minutes

# Construct URL with path
url = f"{server_url}/signalk/v1/{path}"

# Set headers with API token
headers = {
    "Authorization": f"Bearer {api_token}",
    "Content-Type": "application/json",
}

# Data to send in PUT request
#----------------------Changed here 
data = {"updates": [{"values": [{"path": "electrical.batteries.999.capacity.timeRemaining", "value": 1234}]}]}

try:
  # Send PUT request
  response = requests.put(url, headers=headers, json=data)

  # Check for successful response
  if response.status_code == 200:
    print("Value written successfully to Signal K path:", path)
  else:
    print(f"Error writing to Signal K path: {path}. Status code: {response.status_code}")
    print(response.text)

except requests.exceptions.RequestException as e:
  print(f"Error: {e}")

)

Roger•6mo ago

A 401 error suggests that the token is invalid or expired.

Johnathan B•6mo ago

Thanks for taking the time to reply Roger.
Here is is the same code but this time it includes getting a token when first run instead of using and access request. This gives a response of 400, but returns some HTML saying their is a problem with the Json. The output of my code looks like this. If I check the posted json in the datafiddler it validates post fine. {'Authorization': 'Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6ImFkbWluIiwiaWF0IjoxNzExNTM4MjU0LCJleHAiOjE3OTc5MzgyNTR9.oo0FWBOFVRbzv-bA0TzEqzyG4ydAPZL5AkfJRmtF37Y', 'Content-Type': 'application/json'} {"updates": [{"values": [{"path": "electrical.batteries.999.capacity.timeRemaining", "value": 1234}]}]} http://192.168.2.133:3000/signalk/v1/api/ Error writing to Signal K path: api/. Status code: 400 html> <head> <meta charset='utf-8'> <title>SyntaxError: Unexpected token " in JSON at position 0</title> ...... more HTML The stakctrace is: <ul id="stacktrace"><li>    at JSON.parse (<anonymous>)</li><li>    at createStrictSyntaxError (/usr/local/lib/node_modules/signalk-server/node_modules/body-parser/lib/types/json.js:169:10)</li><li>    at parse (/usr/local/lib/node_modules/signalk-server/node_modules/body-parser/lib/types/json.js:86:15)</li><li>    at /usr/local/lib/node_modules/signalk-server/node_modules/body-parser/lib/read.js:128:18</li><li>    at AsyncResource.runInAsyncScope (node:async_hooks:203:9)</li><li>    at invokeCallback (/usr/local/lib/node_modules/signalk-server/node_modules/raw-body/index.js:238:16)</li><li>    at done (/usr/local/lib/node_modules/signalk-server/node_modules/raw-body/index.js:227:7)</li><li>    at IncomingMessage.onEnd (/usr/local/lib/node_modules/signalk-server/node_modules/raw-body/index.js:287:7)</li> The odd thing is I can successfully post the same json using websockets in Python. My test code for the output above is: (


import requests
import json

# Replace with your Signal K server URL and API token
server_url = "http://192.168.2.133:3000"
api_token = ""

# Path to write to
path = "api/"   #----------------------Changed here 
value = 120  # Example value in minutes
# Construct URL with path
url = f"{server_url}/signalk/v1/{path}"

# Function to obtain an authentication token
def get_token():
    login_url = "http://192.168.2.133:3000/signalk/v1/auth/login"
    credentials = {"username": "admin", "password": "******"}
    response = requests.post(login_url, json=credentials)
    if response.status_code == 200:
        return response.json().get("token")
    else:
        print("Failed to authenticate.")
        return None

api_token=get_token()
# Set headers with API token
headers = {
    "Authorization": f"Bearer {api_token}",
    "Content-Type": "application/json",
}

# Data to send in PUT request
#----------------------Changed here  this json works fine int he data fiddler
data = {"updates": [{"values": [{"path": "electrical.batteries.999.capacity.timeRemaining", "value": 1234}]}]}
print(headers)
print(json.dumps(data))
print(url)
try:
  # Send PUT request
  response = requests.put(url, headers=headers, json=json.dumps(data))

  # Check for successful response
  if response.status_code == 200:
    print("Value written successfully to Signal K path:", path)
  else:
    print(f"Error writing to Signal K path: {path}. Status code: {response.status_code}")
    print("********** RESPONSE **********")
    print(response.text)

except requests.exceptions.RequestException as e:
  print(f"Error: {e}")

)

Roger•6mo ago

Perhaps json.dumps(data) is stripping the { } from around the data object. Python isn't one of my strong languages, but in other languages, { } is shorthand for an object, and would be removed when converting to json. Try wrapping your data in an extra pair of { }. eg. {{"updates": [{"values": [{"path": "electrical.batteries.999.capacity.timeRemaining", "value": 1234}]}]}}

Johnathan B•6mo ago

I have tried this as well as sending it as a string - and I get the same result. This morning I rewrote the code in micropython and I get the same result as I do in Python and circuit Python. I really don't understand. I communicate with some of my Victron kit in exactly this way but I must be doing something wrong. In signalK is there a way of seeing the 'bad' inbound json string? I can only see log that says SyntaxError: Unexpected token " in JSON at position 0 at JSON.parse (<anonymous>) at createStrictSyntaxError I don't know where to go now. Any help from anyone would be appreciated. Below is the output of my code. With the headers, json and response printed to the screen. {'Authorization': 'Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6ImFkbWluIiwiaWF0IjoxNzExOTY0NjI2LCJleHAiOjE3OTgzNjQ2MjZ9.uWqOLURCasix1-LsDRmJSpjC-bkdnlPLjpiMbFnjL90', 'Content-Type': 'application/json'} {"updates": [{"values": [{"path": "electrical.batteries.999.capacity.timeRemaining", "value": 1234}]}]} http://192.168.2.133:3000/signalk/v1/api/ Error writing to Signal K path: api/. Status code: 400 ** RESPONSE ** <html> <head> <meta charset='utf-8'> <title>SyntaxError: Unexpected token " in JSON at position 0</title>

Roger•6mo ago

" is a “ and json must start with a {. I suspect that python has a function to create valid json from a string value. Try generating your json as a string (wrap it in “s) and use that function to generate valid json.

Johnathan B•6mo ago

For anyone reading this in the future, it appears that what I am trying to do is not possible. And it is not possible to update a path's value via the rest API and it can only be done via a websockets / UDP connection.

barnaclebill•4mo ago

Hi Jonathan, did you get this working with either websockets or UDP? I would like to post a simple path update like you're doing here.

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Johnathan B - HiCould someone point me in the ...