ho usato una classe derivata da FileResult
di raggiungere questo obiettivo con una normale pattern MVC:
/// <summary>
/// MVC action result that generates the file content using a delegate that writes the content directly to the output stream.
/// </summary>
public class FileGeneratingResult : FileResult
{
/// <summary>
/// The delegate that will generate the file content.
/// </summary>
private readonly Action<System.IO.Stream> content;
private readonly bool bufferOutput;
/// <summary>
/// Initializes a new instance of the <see cref="FileGeneratingResult" /> class.
/// </summary>
/// <param name="fileName">Name of the file.</param>
/// <param name="contentType">Type of the content.</param>
/// <param name="content">Delegate with Stream parameter. This is the stream to which content should be written.</param>
/// <param name="bufferOutput">use output buffering. Set to false for large files to prevent OutOfMemoryException.</param>
public FileGeneratingResult(string fileName, string contentType, Action<System.IO.Stream> content,bool bufferOutput=true)
: base(contentType)
{
if (content == null)
throw new ArgumentNullException("content");
this.content = content;
this.bufferOutput = bufferOutput;
FileDownloadName = fileName;
}
/// <summary>
/// Writes the file to the response.
/// </summary>
/// <param name="response">The response object.</param>
protected override void WriteFile(System.Web.HttpResponseBase response)
{
response.Buffer = bufferOutput;
content(response.OutputStream);
}
}
Il metodo di controllo sarebbe ora essere simile a questo:
public ActionResult Export(int id)
{
return new FileGeneratingResult(id + ".csv", "text/csv",
stream => this.GenerateExportFile(id, stream));
}
public void GenerateExportFile(int id, Stream stream)
{
stream.Write(/**/);
}
Si noti che se il buffering è disattivato,
stream.Write(/**/);
diventa estremamente lento. La soluzione è usare un BufferedStream. In questo caso, prestazioni migliorate di circa 100 volte. Vedere
Unbuffered Output Very Slow
fonte
2012-11-19 14:50:55
È necessario evitare Response.End() http://stevesmithblog.com/blog/use-httpapplication-completerequest-instead-of-response-end/ –
Aggiornato quindi per utilizzare CompleteRequest(). – womp
Può essere utile per sostituire "return View()" di "return Content (" ")" per evitare errori sulla vista mancante. Ma questo approccio è sicuro? –