Question

In PHP, it is possible to return a file to the browser by echoing it out with the correct header. You do not need to save a copy of it prior on the server.

So assuming I have a bunch of data I wish to return as a excel file – after creating the data structure using OpenXML, how can I serve the file to the user without saving it on the server first?

Answer 1

Write your data to a stream and return it from your controller action method in a FileStreamResult by setting the FileStream, ContentType and FileDownloadName properties.

    [HttpGet]
    public FileStreamResult MyFile()
    {
        var fileStreamResult = new FileStreamResult (GetMyContentAsStream(), "my/content-type-here");
        fileStreamResult.FileDownloadName = "my-file-download-name.here";

        return fileStreamResult ;
    }

Update:
A short cut for doing this, is to use the Controller.File() method.

    [HttpGet]
    public FileStreamResult MyFile()
    {
        return File(GetMyContentAsStream(), "my/content-type-here");
    }