Can't access fetch post data in controller: Codeigniter

Question

I'm making a post request using fetch in my codeigniter project. The request looks like this

fetch('myurl/mycontroller', {
    method: 'POST',
    headers: {
        "Content-Type": "application/json"
    },
    body: JSON.stringify({
         testdata: 123,
    })
 }).then((res) => {
    console.log(res);
 }).catch(console.log);

My controller looks like below

class MyController extends CI_Controller
{
    public function mycontroller()
    {
        $data = $this->input->post('testdata');
        return $data . " is the passed data.";
    }
}

But the data isn't getting passed to my controller. I echoed out $_POST and it gave me an empty array. Any idea what I'm doing wrong? I'm using codeigniter 2 (which I know is very old now)

Answer 1

So not completely sure about the actual reason but there might be some bug with the CI core of codeigniter which doesn't parse the data passed to controller using fetch. Using FormData() and axios I was able to resolve the issue.

 var postData = new FormData();
 postData.append('testdata', 123);
 axios.post('myurl/mycontroller', postData).then(function(response){
     console.log("success:", response);
 }).catch(function(error){
     console.log("error:", error);
 });