Return file in ASP.Net Core Web API

Question

Problem I want to return a file in my ASP.Net Web API Controller, but all my approaches return the `HttpResponseMessage` as JSON. Code so far ``` public async Task<HttpResponseMessage> DownloadAsync(string id) { var response = new HttpResponseMessage(HttpStatusCode.OK); response.Content = new StreamContent({{__insert_stream_here__}}); response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream"); return response; } ``` When I call this endpoint in my browser, the Web API returns the `HttpResponseMessage` as JSON with the HTTP Content Header set to `application/json`.

Accepted Answer

If this is ASP.net-Core then you are mixing web API versions. Have the action return a derived `IActionResult` because in your current code the framework is treating `HttpResponseMessage` as a model.

```
[Route("api/[controller]")]
public class DownloadController : Controller {
    //GET api/download/12345abc
    [HttpGet("{id}")]
    public async Task<IActionResult> Download(string id) {
        Stream stream = await {{__get_stream_based_on_id_here__}}

if(stream == null)
            return NotFound(); // returns a NotFoundResult with Status404NotFound response.

return File(stream, "application/octet-stream", "{{filename.ext}}"); // returns a FileStreamResult
    }    
}
```

Note:

The framework will dispose of the stream used in this case when the response is completed. If a `using` statement is used, the stream will be disposed before the response has been sent and result in an exception or corrupt response.

Return file in ASP.Net Core Web API

Solution

Problem