How can I form this http request correctly in matlab

This request, expressed in XML, works fine in a rest client.

I should clarify, that I work inside a corporate firewall. The request goes outside that.

<RestClientRequest>
<option name="httpMethod" value="POST" />
<option name="urlBase" value="https://aWebsite.net" />
<option name="urlPath" value="/atoken" />
<option name="headers">
  <list>
    <KeyValuePair>
      <option name="key" value="Content-Type" />
      <option name="value" value="application/x-www-form-urlencoded" />
    </KeyValuePair>
    <KeyValuePair>
      <option name="key" value="Cache-Control" />
      <option name="value" value="no-cache" />
    </KeyValuePair>
  </list>
</option>
<option name="parameters">
  <list>
    <KeyValuePair>
      <option name="key" value="username" />
      <option name="value" value="me" />
    </KeyValuePair>
    <KeyValuePair>
      <option name="key" value="password" />
      <option name="value" value="verySecret" />
    </KeyValuePair>
    <KeyValuePair>
      <option name="key" value="grant_type" />
      <option name="value" value="password" />
    </KeyValuePair>
  </list>
</option>
<option name="parametersEnabled" value="true" />
<option name="haveTextToSend" value="false" />
<option name="haveFileToSend" value="false" />
<option name="isFileUpload" value="false" />
<option name="textToSend" value="" />
<option name="filesToSend" value="" />
</RestClientRequest>

For the life of me, I cannot express it in matlab, I only ever get back 'Bad Request'. Can anyone help?

 api = 'https://aWebsite.net/aToken';

 body.username = 'me';
 body.password = 'verySecret';
 body.grant_type = 'password';

 options = weboptions('MediaType', 'application/json' ,'RequestMethod','post','ArrayFormat','json');
respon = webwrite(api, body, options);

[Simon Parten]

equally useless...

headerField = matlab.net.http.field.ContentTypeField('application/x-www-form-urlencoded');
un = 'me';
pw = 'verySecret';
input = struct('Username',un,'Password',pw, 'grant_type', 'password');
inputParameters = struct('parameters', input);
aTest = jsonencode(inputParameters);

options = matlab.net.http.HTTPOptions();

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

request = matlab.net.http.RequestMessage(method,headerField, aTest);
show(request)

resp = send(request,uri, options);

Answer 1

[Sonam Gupta]

According to my understanding, you want to read content from a RESTful webservice. When query parameters are to be appended to the URL, something like following should work:

url = 'https://aWebsite.net/aToken';
options = weboptions('RequestMethod', 'post', 'ArrayFormat','json');
data = webread(url,'username', 'me', 'password', 'verySecret', 'grant_type', 'password', options);

To encode the name-value pairs in the body of an HTTP POST request to the web service, you need to use webwrite. The web service defines response. Following example shows how you can use webwrite:

https://in.mathworks.com/help/matlab/ref/webwrite.html#buocii8-2

You can find more information and example about 'webread' and 'webwrite' at following links:

https://in.mathworks.com/help/matlab/ref/webread.html

https://in.mathworks.com/help/matlab/ref/webwrite.html

[Simon Parten]

Sadly, this doesn't work. I've had sucess with Excel VBA as follows.

   Function getToken()

    Dim xmlhttp As New MSXML2.XMLHTTP60
    Dim myurl As String
    Dim iCreds As iLogin

    myurl = iStub & "aToken"

    xmlhttp.Open "POST", myurl, False
    xmlhttp.setRequestHeader "Content-Type", "application/x-www-form-urlencoded"
    xmlhttp.setRequestHeader "Cache-Control", "no-cache"

    ilmaCreds = readiLogin()
    uname = iCreds.name
    pword = iCreds.pword

    xmlhttp.Send "grant_type=password&username=" & uname & "&password=" & pword

    Set json = ParseJson(xmlhttp.responseText)

    getToken = json("access_token")

   End Function

When trying to reproduce this request in matlab, I have never managed to get any response other than 'Bad Request'. This makes me suspicious about the underlying mechanism and / or error message that is being reported.

[Simon Parten]

There was a deeper problem to do with security. Once that was fixed, it was easy to form web requests as per the documentation.