J'ai utilisé une classe dérivée de FileResult
pour y parvenir en utilisant modèle normal 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);
}
}
La méthode du contrôleur serait maintenant comme ceci:
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(/**/);
}
Notez que si la mise en mémoire tampon est désactivée,
stream.Write(/**/);
devient extrêmement lent. La solution consiste à utiliser un BufferedStream. Cela a permis d'améliorer les performances d'environ 100x dans un cas. Voir
Unbuffered Output Very Slow
Vous devriez éviter Response.End() http://stevesmithblog.com/blog/use-httpapplication-completerequest-instead-of-response-end/ –
Mise à jour puis utilisation de CompleteRequest(). – womp
Peut être utile de remplacer "return View()" par "return Content (" ")" pour éviter les erreurs sur les vues manquantes. Mais cette approche est-elle sûre? –