How can I POST JSON arguments (Request Payload) using MATLAB's webwrite?

I am using a data acquisition module with a web server. I would like to Post a run command to start an acquisition. Below are my commands with the error response.

>> s_sch = 'http://webdaq316-ae.local/api/v1.0/schedule/status/';

>> options = weboptions('ContentType','json','MediaType','application/json','RequestMethod','post','ArrayFormat','json')

options =

weboptions with properties:

CharacterEncoding: 'auto'

UserAgent: 'MATLAB 9.5.0.944444 (R2018b)'

Timeout: 5

Username: ''

Password: ''

KeyName: ''

KeyValue: ''

ContentType: 'json'

ContentReader: []

MediaType: 'application/json'

RequestMethod: 'post'

ArrayFormat: 'json'

HeaderFields: []

CertificateFilename: 'C:\Program Files\MATLAB\R2018b\sys\certificates\ca\rootcerts.pem'

>> apikey = 'True'

apikey =

'True'

>> json_command = ['{"run": ', apikey,'}']

json_command =

'{"run": True}'

>> start_sch = webwrite(s_sch,json_command, options)

However, I get the following error.

Error using readContentFromWebService (line 46)

The server returned the status 415 with message "" in response to the request to URL

http://webdaq316-ae.local/api/v1.0/schedule/status/.

Error in webwrite (line 139)

[varargout{1:nargout}] = readContentFromWebService(connection, options);

[Fausto Soares]

If I start the acquisition via the web server, then I can see the POST (using Google Chrome's Developer Tools option), which contains the 'Request Payload' with the code:

{run: true}

I included these parameters in my 'json_command' argument. Is that the correct way?

Answer 1

[Neeraj Rajpurohit]

The error code here is 415, which means unsupported media type. The server is not being able to identify the request type. I see that you have added 'Arraytype' as 'json'. Instead, I suggest you to 'MediaType' attribute as 'application/json'. See the below example for reference. I am also attaching a link to the document. Hope it helps!

weboptions('MediaType','application/json');

https://www.mathworks.com/help/matlab/ref/webwrite.html#buoy23t

Thanks,

Neeraj

Answer 2

[Mudabbir Bhatti]

Hi Fausto,

I am having a similar problem. If you were able to solve this issue, please help me.

Thanks,

Bhatti