How to enable cross origin requests in ASP.NET MVC 4 on POST using Angular 2

Question

I'm trying to make a POST request with CORS. I've a class that adds the correct response header on my methods inside my controller ``` using System; using System.Web.Mvc; public class AllowCrossSiteAttribute : ActionFilterAttribute { public override void OnActionExecuting(ActionExecutingContext filterContext) { filterContext.RequestContext.HttpContext.Response.AddHeader("Access-Control-Allow-Origin", "http://localhost:4200"); filterContext.RequestContext.HttpContext.Response.AddHeader("Access-Control-Allow-Headers", "*"); filterContext.RequestContext.HttpContext.Response.AddHeader("Access-Control-Allow-Credentials", "true"); base.OnActionExecuting(filterContext); } } ``` and I use it like this ``` [AllowCrossSite] public ActionResult GetReportParameters(string IdRapport) ``` and I get the expected result But the problem is when I'm trying to make a POST request with a custom header to pass this specific content type ``` 'Content-Type': 'application/json; charset=utf-8' ``` I'm actuall…

Accepted Answer

I found how to make it work. First I apply what proposed me sideshowbarker

```
if (Request.Headers.AllKeys.Contains("Origin", StringComparer.OridinalIgnoreCase) &&
    Request.HttpMethod == "OPTIONS") {
    Response.Flush();
}
```

and I was missing something in my Headers, I was doing "*" all the way but finally with these parameters it worked

```
filterContext.RequestContext.HttpContext.Response.AddHeader("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
```

for those who are interested in the final form of my class here it is

```
using System;
using System.Web;
using System.Web.Mvc;

namespace Via.Client.WebMvc
{
    public class AllowCrossSiteAttribute : System.Web.Mvc.ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext filterContext)
        {    
            filterContext.RequestContext.HttpContext.Response.AddHeader("Access-Control-Allow-Origin", "http://localhost:4200");
            filterContext.RequestContext.HttpContext.Response.AddHeader("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
            filterContext.RequestContext.HttpContext.Response.AddHeader("Access-Control-Allow-Credentials", "true");

if (filterContext.HttpContext.Request.HttpMethod == "OPTIONS")
            {
                filterContext.HttpContext.Response.Flush();
            }

base.OnActionExecuting(filterContext);
        }
    }
}
```

How to enable cross origin requests in ASP.NET MVC 4 on POST using Angular 2

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