public async Task <IActionResult> EditNews(News news, List <IFormFile> files)
        {
            if (ModelState.IsValid)
            {
                News item = await _dbContext.News.Include(p => p.Images).SingleOrDefaultAsync(p => p.Id == news.Id);

                //修改新闻信息
                if (item != null)
                {
                    if (files.Count() > 0)
                    {
                        news.Images = new List <NewsImage>();
                        foreach (var f in files)
                        {
                            news.Images.Add(new NewsImage {
                                Url = f.FileName, NewsId = news.Id, MimeType = f.ContentType
                            });
                        }
                    }
                    //上传的图片文件夹路径
                    string upPath = Path.Combine(_env.WebRootPath, "images");
                    //原图片路径
                    List <string> paths = new List <string>();
                    foreach (string i in await GetImageUrl(item.Id))
                    {
                        paths.Add(Path.Combine(_env.WebRootPath, i));
                    }
                    //删除原图片并上传新图片
                    MyFile.Remove(paths);
                    MyFile.Up(upPath, files).Wait();
                    //保存修改后的新闻信息
                    item.CopyFrom(news);
                    await _dbContext.SaveChangesAsync();

                    TempData["Message"] = "编辑成功!";
                    return(RedirectToAction("Index"));
                }
            }
            return(View(news));
        }