有没有一种方法可以重命名上载的文件而不保存它？

Question

I tried looking into other solutions , however they suggest either:

1. to save the file with a different name with saveAs()
2. to change the file name once the file is saved with Move() or Copy()

In my case I need to rename it without saving it . I tried changing the file.FileName property, however it is ReadOnly .

The result I'm trying to get is:

public HttpPostedFileBase renameFiles(HttpPostedFileBase file)
{
    //change the name of the file
    //return same file or its copy with a different name
}

It would be good to have HttpPostedFileBase as a return type , however it can be sacrificed if needed.

Is there a way to do this through memory streams or anything else? I appreciate any help, thank you for taking your time to read this. :)

Answer 1

Short Answer: NO

Long Answer: You can rename a file only if file exists on File System.

The files uploaded are not files at all - when you access them using Request.Files. They are streams. The fileName property is readonly because of the same reason.

There is no name associated with stream.

As per documentation, FileName property

Gets the fully qualified name of the file on the client.

Answer 2

Well, I finally found a way that's really simple - I guess I was overthinking this a bit. I figured I'll just share the solution, since some of you might need it. I tested it and it works for me.

You just have to create your own class HttpPostedFileBaseDerived that inherits from HttpPostedFileBase . The only difference between them is that you can make a constructor there.

    public class HttpPostedFileBaseDerived : HttpPostedFileBase
    {
        public HttpPostedFileBaseDerived(int contentLength, string contentType, string fileName, Stream inputStream)
        {
            ContentLength = contentLength;
            ContentType = contentType;
            FileName = fileName;
            InputStream = inputStream;
        }
        public override int ContentLength { get; }

        public override string ContentType { get; }

        public override string FileName { get; }

        public override Stream InputStream { get; }

        public override void SaveAs(string filename) { }

    }
}

Since constructor is not affected by ReadOnly , you can easily copy in the values from your original file object to your derived class's instance , while putting your new name in as well:

HttpPostedFileBase renameFile(HttpPostedFileBase file, string newFileName)
{
    string ext = Path.GetExtension(file.FileName); //don't forget the extension

    HttpPostedFileBaseDerived test = new HttpPostedFileBaseDerived(file.ContentLength, file.ContentType, (newFileName + ext), file.InputStream);
    return (HttpPostedFileBase)test; //cast it back to HttpPostedFileBase 
}

Once you are done you can type cast it back to HttpPostedFileBase so you wouldn't have to change any other code that you already have.

Hope this helps to anyone in the future. Also thanks to Manoj Choudhari for his answer, thanks to I learned of where not to look for the solution.