How to set custom headers when using IHttpActionResult?

Question

In ASP.NET Web API 2, the IHttpActionResult offers a lot of value in simplifying controller code and I\'m reluctant to stop using it, but I\'ve hit a problem.

Answer 1

very old question. Probably other answers made sense that time but today you can simply add this line without changing or extending IHttpActionResult. It perfectly adds header in your response. Make sure also to format into RFC 1123 standard as below. Otherwise, although Last-Modified appears in the headers, Client is not able to read it using HttpClient.

    System.Web.HttpContext.Current.Response.Headers.
Add(Microsoft.Net.Http.Headers.HeaderNames.LastModified, DBdateModified.Value.ToString("r"));