Returning binary file from controller in ASP.NET Web API

Question

I\'m working on a web service using ASP.NET MVC\'s new WebAPI that will serve up binary files, mostly .cab and .exe files.

The following co

Answer 1

While the suggested solution works fine, there is another way to return a byte array from the controller, with response stream properly formatted :

• In the request, set header "Accept: application/octet-stream".
• Server-side, add a media type formatter to support this mime type.

Unfortunately, WebApi does not include any formatter for "application/octet-stream". There is an implementation here on GitHub: BinaryMediaTypeFormatter (there are minor adaptations to make it work for webapi 2, method signatures changed).

You can add this formatter into your global config :

HttpConfiguration config;
// ...
config.Formatters.Add(new BinaryMediaTypeFormatter(false));

WebApi should now use BinaryMediaTypeFormatter if the request specifies the correct Accept header.

I prefer this solution because an action controller returning byte[] is more comfortable to test. Though, the other solution allows you more control if you want to return another content-type than "application/octet-stream" (for example "image/gif").