public string UpImg(IFormatProvider file, string filename)
{
if (file == null || !ContentType.StartsWith("image"))
{
return(null);
}
else
{
string ext = Path.GetExtension(file.FileName);
filename = $"{filename}{ext}";
using (FileStream fs = File.Create(filename))
{
file.CopyTo(fs);
fs.Flush();
}
return(ext);
}
}