用ASP.NET MVC下载后如何删除文件？

Question

I want to delete a file immediately after download, how do I do it? I've tried to subclass FilePathResult and override the WriteFile method where I delete file after

HttpResponseBase.TransmitFile

is called, but this hangs the application.

Can I safely delete a file after user downloads it?

Answer 1

Read in the bytes of the file, delete it, call the base controller's File action.

public class MyBaseController : Controller
{
    protected FileContentResult TemporaryFile(string fileName, string contentType, string fileDownloadName)
    {
        var bytes = System.IO.File.ReadAllBytes(fileName);
        System.IO.File.Delete(fileName);
        return File(bytes, contentType, fileDownloadName);
    }
}

BTW, you may refrain from this method if you're dealing with very large files, and you're concerned about the memory consumption.

Answer 2

Create file and save it.
Response.Flush() sends all data to client.
Then you can delete temporary file.

This works for me:

FileInfo newFile = new FileInfo(Server.MapPath(tmpFile));

//create file, and save it
//...

string attachment = string.Format("attachment; filename={0}", fileName);
Response.Clear();
Response.AddHeader("content-disposition", attachment);
Response.ContentType = fileType;
Response.WriteFile(newFile.FullName);
Response.Flush();
newFile.Delete();
Response.End();

Answer 3

You can return just regular FileStreamResult which is opened with FileOptions.DeleteOnClose . File stream will be disposed with result by asp.net. This answer dosen't require usage of low level response methods which may backfire in certain situations. Also no extra work will be done like loading file to memory as whole.

var fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.None, 4096, FileOptions.DeleteOnClose);
return File(
    fileStream: fs,
    contentType: System.Net.Mime.MediaTypeNames.Application.Octet,
    fileDownloadName: "File.abc");

This answer is based on answer by Alan West and comment by Thariq Nugrohotomo.

Answer 4

Above answers helped me, this is what I ended up with:

public class DeleteFileAttribute : ActionFilterAttribute
{
  public override void OnResultExecuted(ResultExecutedContext filterContext)
  {
     filterContext.HttpContext.Response.Flush();
     var filePathResult = filterContext.Result as FilePathResult;
     if (filePathResult != null)
     {
        System.IO.File.Delete(filePathResult.FileName);
     }
  }
}

Answer 5

You could create a custom actionfilter for the action with an OnActionExecuted Method that would then remove the file after the action was completed, something like

public class DeleteFileAttribute : ActionFilterAttribute 
{ 
    public override void OnActionExecuted(ActionExecutedContext filterContext) 
    { 
        // Delete file 
    } 
} 

then your action has

[DeleteFileAttribute]
public FileContentResult GetFile(int id)
{
   ...
}

Answer 6

I performed same action in WebAPI. I needed to delete file just after it downloaded form server. We can create custom response message class. It takes file path as parameter and delete it once its transmitted.

 public class FileHttpResponseMessage : HttpResponseMessage
    {
        private readonly string filePath;

        public FileHttpResponseMessage(string filePath)
        {
            this.filePath = filePath;
        }

        protected override void Dispose(bool disposing)
        {
            base.Dispose(disposing);
            File.Delete(filePath);
        }
    }

Use this class as below code and it will delete your file once it will be written on response stream.

var response = new FileHttpResponseMessage(filePath);
            response.StatusCode = HttpStatusCode.OK;
            response.Content = new StreamContent(new FileStream(filePath, FileMode.Open, FileAccess.Read));
            response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
            {
                FileName = "MyReport.pdf"
            };
            return response;

Answer 7

overriding the OnResultExecuted method is probably the correct solution.. This method runs after the response is written.

public class DeleteFileAttribute : ActionFilterAttribute 
{ 
    public override void OnResultExecuted(ResultExecutedContext filterContext) 
    { 
        filterContext.HttpContext.Response.Flush();
        // Delete file 
    } 
} 

Action code:

[DeleteFileAttribute]
public FileContentResult GetFile(int id)
{
   //your action code
}

Answer 8

Try This. This will work properly.

public class DeleteFileAttribute : ActionFilterAttribute
{
  public override void OnResultExecuted( ResultExecutedContext filterContext )
  {
    filterContext.HttpContext.Response.Flush();
    string filePath = ( filterContext.Result as FilePathResult ).FileName;
    File.Delete( filePath );
  }
}

Answer 9

My used pattern.

1)Create file.

2)Delete old created file, FileInfo.CreationTime < DateTime.Now.AddHour(-1)

3)User downloaded.

How about this idea?

Answer 10

SOLUTION:

One should either subclass the FileResult or create a custom action filter, but the tricky part is to flush the response before trying to delete the file.

Answer 11

Here is updated answer based on elegant solution by @biesiad for ASP.NET MVC ( https://stackoverflow.com/a/4488411/1726296 )

Basically it returns EmptyResult after response is sent.

public ActionResult GetFile()
{
    string theFilename = "<Full path your file name>"; //Your actual file name
        Response.Clear();
        Response.AddHeader("content-disposition", "attachment; filename=<file name to be shown as download>"); //optional if you want forced download
        Response.ContentType = "application/octet-stream"; //Appropriate content type based of file type
        Response.WriteFile(theFilename); //Write file to response
        Response.Flush(); //Flush contents
        Response.End(); //Complete the response
        System.IO.File.Delete(theFilename); //Delete your local file

        return new EmptyResult(); //return empty action result
}

Answer 12

I preferred a solution which returned an HttpResponseMessage . I liked the simplicity of Risord's answer, so I created a stream in the same manner. Then, instead of returning a File , I set the HttpResponseMessage.Content property to a StreamContent object.

var fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.None, 4096, FileOptions.DeleteOnClose);
return new HttpResponseMessage()
{
    Content = new StreamContent(fs)
};

Answer 13

I have posted this solution in https://stackoverflow.com/a/43561635/1726296

public ActionResult GetFile()
    {
            string theFilename = "<Full path your file name>"; //Your actual file name
            Response.Clear();
            Response.AddHeader("content-disposition", "attachment; filename=<file name to be shown as download>"); //optional if you want forced download
            Response.ContentType = "application/octet-stream"; //Appropriate content type based of file type
            Response.WriteFile(theFilename); //Write file to response
            Response.Flush(); //Flush contents
            Response.End(); //Complete the response
            System.IO.File.Delete(theFilename); //Delete your local file

            return new EmptyResult(); //return empty action result
    }