ASP.NET 5 Controller method can't receive JSON POST, ASP.NET 4 controller method does

Question

I have been tearing my hair out over this one. I have two projects one running ASP.NET 4 and the other ASP.NET 5 RC1

The ASP.NET 5 project controller received POST method input parameters are all default and not the values as sent from the webpage.

To narrow down the problem I simplified the controllers POST methods in both projects

[HttpPost]
public JsonResult DataHandler(int Draw)
{
    //above Draw variable not set
}

and put a break point on the method to catch the variable Draw. The webpage sends a JSON post with a value of 1 for the Draw parameter. However in ASP.NET 5 that values is 0 (default) and other parameters I send are null instead of having values. In 'ASP.NET 4' it is correct.

I am using jquery datatables and the same code as used in this ASP.NET 4 project

var oTable = $('#datatab').DataTable({
    "serverSide": true,
    "ajax": {
        "type": "POST",
        "url": '/Home/DataHandler',
        "contentType": 'application/json; charset=utf-8',
        'data': function (data) { return data = JSON.stringify(data); }
    },
    "dom": 'frtiS',
    "scrollY": 500,
    "scrollX": true,
    "scrollCollapse": true,
    "scroller": {
        loadingIndicator: false
    },
    "processing": true,
    "paging": true,
    "deferRender": true,
    "columns": [
   { "data": "Name" },
   { "data": "City" },
   { "data": "Postal" },
   { "data": "Email" },
   { "data": "Company" },
   { "data": "Account" },
   { "data": "CreditCard" }
    ],
    "order": [0, "asc"]
});

I used Fiddler and compared the JSON sent by both project to the controller and the JSON content posted to the /Home/DataHandler for both are the exact same i.e. Draw=1.

{"draw":1,"columns":[{"data":"Name","name":"","searchable":true,"orderable":true,"search":{"value":"","regex":false}},{"data":"City","name":"","searchable":true,"orderable":true,"search":{"value":"","regex":false}},{"data":"Postal","name":"","searchable":true,"orderable":true,"search":{"value":"","regex":false}},{"data":"Email","name":"","searchable":true,"orderable":true,"search":{"value":"","regex":false}},{"data":"Company","name":"","searchable":true,"orderable":true,"search":{"value":"","regex":false}},{"data":"Account","name":"","searchable":true,"orderable":true,"search":{"value":"","regex":false}},{"data":"CreditCard","name":"","searchable":true,"orderable":true,"search":{"value":"","regex":false}}],"order":[{"column":0,"dir":"asc"}],"start":0,"length":126,"search":{"value":"","regex":false}}

Things I tried.

I used the same html table contents and above code .js file between projects
Set my controller input parameter to lowercase e.g. draw
Compare the JSON POST data in fiddler is the same
Put a breakpoint on the POST method input variable to catch the value as soon as it is posted

Try removing contentType and data from the ajax section of the DataTable setup. — Jamie Dunstan

Programmer Programmer · Accepted Answer · 2019-01-26T01:03:56

Add dataType: 'json' to the ajax call

Replace return data = JSON.stringify(data) with the following:

return data.Draw = JSON.stringify(data)

ASP.NET 5 Controller method can't receive JSON POST, ASP.NET 4 controller method does

1 Answers