Miagration Asp.Net Core 2 to .Net 6 gave me XMLHttpRequest problems-CodePudding

I folks, I just migrated my ASP.Net Core 2 MVC app to .Net 6, but since that, I have a weird problem: my XMLHttpRequest responses texts are always empty, "{}" or [{},{},{},{}] for arrays, despite my backend really returning data.

Here's an example of a controler method (TestLoad) returning a simple class (TestClass). Notice that when I break on the return line, the value returned is ok, or at least I don't see anything wrong (see image for debug infos): backend

public class TestClass
{
   public int id = 0;
   public string title = "Title";
   public bool active = false;
}

public JsonResult TestLoad()
{
   TestClass testClass = new TestClass();
   testClass.id = 10;
   testClass.title = "Yeah man!";
   testClass.active = true;

   JsonResult jsonRes = Json(testClass);
   return jsonRes;
}

But once on the front end, I got an empty object, not undefined nor null, but really an empty object (see image for debug infos): frontend

var xmlhttp = new XMLHttpRequest();

xmlhttp.onreadystatechange = function () {
    if (xmlhttp.readyState == 4) {
        if (xmlhttp.status == 200) {
            var dt = JSON.parse(xmlhttp.responseText);
            if (dt == 'err') {   
                alert('error');
            }
            else if (dt !== null) {                    
                alert(dt.title);                    
            }                
        }
        else {
            alert(xmlhttp.status);
        }
    }
}

ldwait(false, false);
xmlhttp.open("GET", rv   "ajxGame/TestLoad", true);
xmlhttp.setRequestHeader('Cache-Control', 'no-store');

xmlhttp.setRequestHeader("Content-Type", "application/json");

xmlhttp.send();

Any help would be greatly appreciated since I completely clueless of what happened. Again, my code hasn't changed, but my project has migrated from .Net Core 2 to .Net 6.

Thank you

CodePudding user response：

Are you using Razor pages in your Asp.net core 6 ?

If so, the way you call your method maybe the issue. For post requests, call from the client ?handler=TestLoad and on the server make sure the method name is OnPostTestLoad().

Get requests are disabled by default and need to be enabled. Microsoft Warning Message

For more info, check this link from Microsoft docs

Another issue maybe the way you return your class. Try returning it as an object instead.

return new JsonResult(new {objClass: testClass});

And on the client side, get your class as an object property

let objClass = result.objClass;

CodePudding user response：

i would add a response type, and replace onreadystatechange with onl oad

    xmlhttp.responseType = 'json';

    xmlhttp.onload = () => {
        console.log("load - "  JSON.stringify(xhr.response));
        var data = xhr.response;
       
    }