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/

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().