How do I dispose my filestream when implementing a file download in ASP.NET?

Question

I have a class DocumentGenerator which wraps a MemoryStream. So I have implemented IDisposable on the class.

I can't see how/where I can possibly dispose it though.

This is my current code, which performs a file download in MVC:

using (DocumentGenerator dg = DocumentGenerator.OpenTemplate(path)) {     /* some document manipulation with the         DocumentGenerator goes here ...*/      return File(dg.GetDocumentStream(), "text/plain", filename); } 

This errors as the stream is closed/disposed before the controller has finished with it. How can I make sure my resources are properly disposed in this situation?

EDIT: My implementation of IDisposable at the moment just disposes the MemoryStream. I know it's not a proper implementation, I just used it as a test. Is there something different I could do here to make it work?

public void Dispose() {     _ms.Dispose();     _ms = null; } 

Answer 1

You don't need to dispose the stream. It will be disposed by the FileStreamResult.WriteFile method. Code excerpt from this class:

public FileStreamResult(Stream fileStream, string contentType) : base(contentType) {     if (fileStream == null)     {         throw new ArgumentNullException("fileStream");     }     this.FileStream = fileStream; }  protected override void WriteFile(HttpResponseBase response) {     Stream outputStream = response.OutputStream;     using (this.FileStream)     {         byte[] buffer = new byte[0x1000];         while (true)         {             int count = this.FileStream.Read(buffer, 0, 0x1000);             if (count == 0)             {                 return;             }             outputStream.Write(buffer, 0, count);         }     } } 

Notice the using. When you call File(dg.GetDocumentStream(), "text/plain", filename) from your controller this invokes the constructor which stores the stream into a public property which is disposed during the rendering.

Conclusion: you don't need to worry about disposing the stream obtain with dg.GetDocumentStream().