'/comments/{id}/upvote' endpoint not detecting `site` parameter

Question

I am trying to experiment with the API for my project.

I am trying to upvote a comment on the SO website to test out the API. My POST request is returning with a status code of 400.

The response -

{"error_id":400,"error_message":"site is required","error_name":"bad_parameter"}

I have tried putting the site parameter in the URL, using the line request_api("/comments/{id}/upvote", "site=stackoverflow.com", "POST", body); (see below code), but it said:

{"error_id":400,"error_message":"POST methods expects all parameters to be submitted as a form, not on the query string","error_name":"bad_parameter"}

Here is my code -

    let key = "{key}", base_url = "https://api.stackexchange.com";

    function request_api(path, params="", method="GET", body=""){
        let xhr = new XMLHttpRequest();
        let url;
        url = base_url + path + "?" + params;
        alert(url);
        xhr.open(method, url, false);
        xhr.setRequestHeader("Content-Type", "application/json")
        xhr.onload = function(){
            if (xhr.status >= 200 && xhr.status < 300){
                window.responseText = xhr.responseText;
            } else {
                alert("Status received is " + xhr.status);
                window.responseText = xhr.responseText;
            };
        };
        xhr.onerror = function(){
            alert("Error " + xhr.status);
            window.responseText = xhr.responseText;
        }
        if (body){
            xhr.send(body);
        } else {
            xhr.send();
        };
    };

    let body = JSON.stringify({
        access_token: login_info.access_token,
        key: key,
        site: "stackoverflow"
    });
    alert(body);
    request_api("/comments/{id}/upvote", "", "POST", body);
    document.write(window.responseText);

Edit: I looked at this post. I tried the solution there (it was the most upvoted and had a bounty). It didn't work.

Edit 2: Same thing with /questions/{id}/upvote

Answer 1

You need to send the POST as application/x-www-form-urlencoded format.