Streaming large file uploads to ASP.NET MVC

Question

For an application I'm working on, I need to allow the user to upload very large files--i.e., potentially many gigabytes--via our website. Unfortunately, ASP.NET MVC appears to load the entire request into RAM before beginning to service it--not exactly ideal for such an application. Notably, trying to circumvent the issue via code such as the following: ``` if (request.Method == "POST") { request.ContentLength = clientRequest.InputStream.Length; var rgbBody = new byte[32768]; using (var requestStream = request.GetRequestStream()) { int cbRead; while ((cbRead = clientRequest.InputStream.Read(rgbBody, 0, rgbBody.Length)) > 0) { fileStream.Write(rgbBody, 0, cbRead); } } } ``` fails to circumvent the buffer-the-request-into-RAM mentality. Is there an easy way to work around this behavior?

Accepted Answer

It turns out that my initial code was basically correct; the only change required was to change

```
request.ContentLength = clientRequest.InputStream.Length;
```

to

```
request.ContentLength = clientRequest.ContentLength;
```

The former streams in the entire request to determine the content length; the latter merely checks the `Content-Length` header, which only requires that the headers have been sent in full. This allows IIS to begin streaming the request almost immediately, which completely eliminates the original problem.

Streaming large file uploads to ASP.NET MVC

Solution

Problem