Moodle REST webservice: Problems sending an array as POST parameter

Question

I'm using the Moodle REST webservice in combination with Qt. Login works, other functions with single parameters are working too.

Now I want to use the function "core_user_update_users" which takes an array as parameter.

The official documentation says:

General Structure:

list of ( 
object {
id int   //ID of the user
username string  Optional //Username policy is defined in Moodle security config.
... //more optional strings
customfields  Optional //User custom fields (also known as user profil fields)
list of ( 
object {
type string   //The name of the custom field
value string   //The value of the custom field
} 
)preferences  Optional //User preferences
list of ( 
object {
type string   //The name of the preference
value string   //The value of the preference
} 
)} 
)

and:

REST (POST parameters)

 users[0][id]= int 
 users[0][username]= string //optional
 //many more parameters, but all optional like above

So I thought this would be my HTTP Request:

auto NetworkPostRequest = QNetworkRequest(QUrl("http://XXX.XXX.XXX.XXX/webservice/rest/server.php?wstoken=XXXXXXXXX&moodlewsrestformat=json&wsfunction=core_user_update_users" ));
NetworkPostRequest.setHeader(QNetworkRequest::ContentTypeHeader,"application/x-www-form-urlencoded");

QByteArray Data;
Data.append("users[0][id]=12");
Data.append("&users[0][firstname]=QtTestname");
this->NetworkAccessManager->put(NetworkPostRequest, Data);

But I get the following debugmessage from moodle:

{
    "debuginfo": "Missing required key in single structure: users",
    "errorcode": "invalidparameter",
    "exception": "invalid_parameter_exception",
    "message": "Invalid parameter value detected"
}

Obviously there is something wrong with Data, but I can't figure it out. Hopefully someone here can help.

Answer 1

The Solution was to add an "&" to the first append of Data.

QByteArray Data;
Data.append("&users[0][id]=12");
Data.append("&users[0][firstname]=QtTestname");
this->NetworkAccessManager->put(NetworkPostRequest, Data);

Moodle functions without an array as argument don't care about that, so it doesn't got my attention until now.