Issue in Enabling CORS for Web API 1, .net 4.0

Question

I need to enable CORS for my Web API and I can't upgrade to Framework 4.5. I've tried to add the following to my Web.config to see if it worked, but it didn't:

<add name="Access-Control-Allow-Origin" value="*" />
<add name="Access-Control-Allow-Headers" value="Accept,Content-Type,X-Requested-With"/>

I am accessing the URL http://localhost:8484/api/values/ from ajax call

and getting bellow error

XMLHttpRequest cannot load http://localhost:8484/api/values. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access. The response had HTTP status code 405.

you're getting problem with Pre Flight Request of OPTIONS verb — Syed Ali Taqi

SmoothyBoothy SmoothyBoothy · Accepted Answer · 2017-05-12T03:37:23

I found this simple solution by charanjit singh. It worked nicely especially if you are stuck with older visual studio 2010 , on .Net 4.0 and of course web api 1. Basically add this function to your Global.asax.cs

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",
                     "GET, POST, PUT, DELETE");
        HttpContext.Current.Response.AddHeader("Access-Control-Allow-Headers",
                     "Content-Type, Accept");
        HttpContext.Current.Response.End();
     }
}

ref. links: note you must scroll to the bottom comments for the answer. http://www.codeguru.com/csharp/.net/net_asp/using-cross-origin-resource-sharing-cors-in-asp.net-web-api.html

Issue in Enabling CORS for Web API 1, .net 4.0

2 Answers