Question

In a controller action, response header is set like this:

HttpContext.Response.AddHeader("key", "value");

In rendered view, Response.Headers[“key”] seems to be null (btw in ajax requests, header is set and retrieved without any problems). Is there any special reason for this or is this a silly bug in my code?

Answer 1

You can only add response headers but you cannot read them unless you are running in IIS 7 integrated pipeline mode. When running in standard model HTTP response headers are sent at a later stage by the time you try to read them in your code. This has been stated in the documentation:

The Headers property is only supported with the IIS 7.0 integrated
pipeline mode and at least the .NET Framework 3.0. When you try to
access the Headers property and either of these two conditions is not
met, a PlatformNotSupportedException is thrown.

This being said, all that a view should access is a view model, not response headers. So in your controller action you will build a view model containing all the information that the view will require and pass it to the view for consumption. Remember: a view doesn’t pull data, a view uses data that it is being handled from the controller under the form of a view model.