Add custom header to all responses in Web API

Question

Simple question, and I am sure it has a simple answer but I can\'t find it.

I am using WebAPI and I would like to send back a custom header to all responses (server

Answer 1

Julian's answer led me to have to create the filter but only using the the System.Web (v4) and System.Web.Http (v5) namespace (MVC packages were not part of this particular project this was used on.)

using System.Web;
using System.Web.Http.Filters;
...
public class AddCustomHeaderActionFilterAttribute : ActionFilterAttribute
{
    public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
    {
        base.OnActionExecuted(actionExecutedContext);
        actionExecutedContext.ActionContext.Response.Headers.Add("name", "value");
    }
}

And add it to the global.asax to have it used on every controller/action

        GlobalConfiguration.Configuration.Filters.Add(new AddCustomHeaderActionFilterAttribute());