Connect Matlab to Octoprint API

I am trying to connect with Octoprint using Matlab code.

From the Octoprint REST API web page I have found this information to connect:

POST /api/connection HTTP/1.1
Host: example.com
Content-Type: application/json
X-Api-Key: abcdef...

{
  "command": "connect",
  "port": "/dev/ttyACM0",
  "baudrate": 115200,
  "printerProfile": "my_printer_profile",
  "save": true,
  "autoconnect": true
}

Based on previous information I am using this code to connect. Unfortunatelly it does not work. Also I do not find the way to specify the request line in order to be "POST /api/connection HTTP/1.1" instead of the usual "POST".

import matlab.net.*
import matlab.net.http.*
import matlab.net.http.field.*

api_key = "some key";
api_url = "some url";

header1 = ContentTypeField('application/json');
header2 = matlab.net.http.HeaderField("X-Api-Key", api_key);

commands= struct('command', 'connect', 'port', 'AUTO', ...
                 'baudrate', 115200, 'printerProfile', 'Default', ...
                 'save', false, 'autoconnect', false);
body    = matlab.net.http.MessageBody(jsonencode(commands));

request = RequestMessage('POST', [header1, header2], body);

[resp, c, h] = request.send(api_url);

[Geoff Hayes]

@Álvaro González Menéndez - when you run the above code, what error are you observing? Presumably it is an HTTP error code of some kind. I've edited out the api key and url as I don't think that is something that you want to be posting publicly (unless already junk data?). Also, I'm not sure if the URL was complete as it just seemed to be a host.

Answer 1

[Álvaro González Menéndez]

Hi Geoff, Thank you for removing the api_key, anyway I had changed some digits to avoid problems. Regarding the address, it is an address inside my home network, I am not trying to reach form outside of my home.

I have improve the code in the meantime, and I now I can reach the server but I get the following response into resp.StatusLineStatusCode: 'InternalServerError', and the following message in resp.Body.Data: 'The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application'. Obviously I have no active connection while I am trying this test and if I try to connect for example using the Octoprint webpage I can connect without errors using the same values for the connection parameters.

        import matlab.net.*
        import matlab.net.http.*

        api_url = matlab.net.URI('http://host_addr/api/connection');       
        api_key = 'api_key';

        method  = matlab.net.http.RequestMethod.POST; 

        header  = matlab.net.http.HeaderField('Content-Type',  'application/json', ...
                                             'X-Api-Key', api_key);

        commands= struct('command', 'connect',...
                         'port',    '/dev/ttyUSB0', ...
                         'baudrate', 115200, ...
                         'printerProfile', '_default');
        
        body    = matlab.net.http.MessageBody(jsonencode(commands));
        
        request = matlab.net.http.RequestMessage(method, header, body);
        
        % Send request to login api
        [resp, complreq, history] = request.send(api_url);
        
        % La respuesta
        resp.StatusLine
       

When I use this code to test that I reach Octoprint, it works. I receive an StatusCode: OK, and the different values available for the connection parameters.

        import matlab.net.*
        import matlab.net.http.*
        
        api_url = matlab.net.URI('http://host_addr/api/connection');
        api_key = 'api_key';
        
        method = matlab.net.http.RequestMethod.GET;
        
        header = matlab.net.http.HeaderField('X-Api-Key', api_key);
        
        request = matlab.net.http.RequestMessage(method, header);
        
        % Send request to login api
        [resp, complreq, history] = request.send(api_url);
        
        % La respuesta
        resp.StatusLine

[Álvaro González Menéndez]

Just some additional information, the variable "complreq" contains the request message which it is very similar to the information provided by the Octoprint REST API web page I posted at the beggining of my first post.

complreq

         Method: POST
    RequestLine: 'POST /api/connection HTTP/1.1'
         Header: [1×8 matlab.net.http.HeaderField]
           Body: [1×1 matlab.net.http.MessageBody]
      Completed: 1

complreq.Body
                   Data: '{"command":"connect","port":"/dev/ttyUSB0","baudrate":115200,"printerProfile":"_default"}'
          Payload: [105×1 uint8]
      ContentType: [1×1 matlab.net.http.MediaType]
    ContentCoding: [0×0 string]

[Álvaro González Menéndez]

In order to avoid a potential problem of connection I have succesfully connect to Octoprint using this code in Python 3.8. This code is very similar to the one implementaed in Matlab.

import requests
api_url   = "http://host_addr/api/connection"
api_key   = 'apy_key'
command   = 'connect'
baudrate  = 115200
port      = '/dev/ttyUSB0'

headers = ({'X-Api-Key': api_key, 'Content-Type': 'application/json'})
data = {'command': 'connect'}
data['port']     = port
data['baudrate'] = baudrate

r = requests.post(api_url, json=data, headers=headers)

[Álvaro González Menéndez]

Solved, finally I have connect to Octoprint using Matlab code. It seems that the key point is to use the following sentence

body = matlab.net.http.MessageBody(commands);

Instead of

body    = matlab.net.http.MessageBody(jsonencode(commands));

So, the final code that it works is:

        import matlab.net.*
        import matlab.net.http.*

        api_url = matlab.net.URI('http://host_addr/api/connection');       
        api_key   = 'apy_key'
        
        method  = matlab.net.http.RequestMethod.POST;
        
        header  = matlab.net.http.HeaderField('Content-Type',  'application/json', ...
                                              'X-Api-Key', api_key);
        
        commands= struct('command', 'connect',...
                         'baudrate', 115200, ...
                         'port', '/dev/ttyUSB0');
     
        body = matlab.net.http.MessageBody(commands);
        request = matlab.net.http.RequestMessage(method, header, body);
        
        [resp, complreq, history] = request.send(api_url);