Net Core Upload File

<form enctype="multipart/form-data" method="post">
    <div>
        <label for="f">Image</label>        <div>
            <input type="file" name="f" id="f">
        </div>
    </div>
    <div>
        <button>Upload</button>
    </div>
</form>

public IActionResult Simple() => View();
[HttpPost]
public IActionResult Simple(IFormFile f){
    if(f != null){
        string ext = Path.GetExtension(f.FileName);
        string fileName = Helper.RandomString(32 - ext.Length) + ext;
        Image obj = new Image{
            Name = f.FileName,
            Length = f.Length,
            ImageUrl = fileName,
                Type = f.ContentType
        };
        string path = Path.Combine(Directory.GetCurrentDirectory(), "wwwroot", "images", fileName);
        using(Stream stream  = new FileStream(path, FileMode.Create)){
            f.CopyTo(stream);
        }
        return Json(obj);
    }
    return Json(null);
}