Sending data to MVC Controller with AJAX - ajax

Question

I am trying to send data with AJAX to MVC Controller method, but I don't know what am I doing wrong.
Here is the AJAX call
$.ajax({
type: 'POST',
url: invokingControllerActionUrl,
data: "it is just a simple string",
success: function (data) {
window.location.href = link;
}
});
And here is the controller method. It is invoked, but the parameter is always null.
public IActionResult OnPostTest([FromBody] string stringValue)
{
// stringValue is always null :(
}

Answer 1

Change you ajax call to this
$.ajax({
type: 'POST',
url: invokingControllerActionUrl, // Confirm the Path in this variable Otherwise use #Url.Action("OnPostTest", "InvokingController")
data: {stringValue: "it is just a simple string"},
success: function (data) {
window.location.href = link;
}
});
And remove the [FromBody]. ALso its better to define type post. Not necessary though
[HttpPost]
public IActionResult OnPostTest( string stringValue)
{
// stringValue is always null :(
}

Answer 2

Depending on what Content-Type you are sending from JS, you might need to encode your string properly, as a form-value
...
data: 'stringValue="it is just a simple string"',
...
or e.g. JSON:
...
data: '{stringValue: "it is just a simple string"}',
...
See also this discussion
I haven't found an easy way to pass a string of unformatted data via parameter, unfortunately. According to this answer, you can do the following:
public IActionResult OnPostTest()
{
Stream req = Request.Body;
req.Seek(0, System.IO.SeekOrigin.Begin);
string stringValue = new StreamReader(req).ReadToEnd();
...
// process your stringValue here
...
}