Enabling CORS in ASP.NET MVC

Question

I have added [System.Web.Http.Cors.EnableCors(origins: "*", headers: "*", methods: "*")] before my public class UPWebsiteAPIController : ApiController and every time I want to POST data my function should return new JsonResult { Data = toReturn };. The thing is that this function is fully executed and returning toRerurn object, but browser gets error code 500 and

No Access-Control-Allow-Origin header is present to the requested resource

Backend code:

        [System.Web.Http.HttpPost]
    public async Task<System.Web.Mvc.ActionResult> CreateEvent(FormDataCollection formData)
    {
        try
        {
            (code which works fine)
            toReturn[0] = HttpStatusCode.OK;
            return new JsonResult { Data = toReturn };
        }
        catch (Exception ex)
        {
            toReturn[0] = HttpStatusCode.BadRequest;
            return new JsonResult { Data = toReturn };
        }
    }

Fronend code:

$.ajax({    
    type: "POST",
    url: 'http://www.XXX.aspnet.pl/api/UPWebsiteAPI/CreateEvent',
    data: data,
    beforeSend: function() {

      $loading.show();

    },

    success: function(response) {
        console.log('sukces');
        console.log(response);

        $loading.hide();
        $response.show();
        $response.find('.pay-button').show();
        $response.find('.pay-link').attr('href', response.Data[1]);

        $response.find('h2').html("Gratulacje!' );

    },
    error: function(response) {
        console.log('error');
        console.log(response);
        $loading.hide();
        $response.show();
        $('.pay-button').hide();
        $response.find('h2').html("Przepraszamy...");
    }
  });

What should I do? Funny thing is that is sometimes works without any problems and sometimes (more than often) gets those errors.

Supraj V · Accepted Answer · 2017-10-24 14:38:47Z

1

In your global.asax.cs file Add the below method.

protected void Application_BeginRequest(object sender, EventArgs e)
    {
        HttpContext.Current.Response.AddHeader("Access-Control-Allow-Origin", "*");
        if (HttpContext.Current.Request.HttpMethod == "OPTIONS")
        {
            HttpContext.Current.Response.AddHeader("Access-Control-Allow-Methods", "POST, PUT, DELETE,GET");

            HttpContext.Current.Response.AddHeader("Access-Control-Allow-Headers", "content-type,Access-Control-Allow-Origin,authToken, Accept");
            HttpContext.Current.Response.AddHeader("Access-Control-Max-Age", "1728000");
            HttpContext.Current.Response.End();
        }
    }

answered Oct 24, 2017 at 14:38

Supraj V

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2 Comments

Cezar Over a year ago

It didn't help me

Supraj V Over a year ago

are you using any token based authentication?

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