ASP.MVC图像编辑

Question

    public ActionResult Edit([Bind(Include = "id,category,title,image,active,ImageFile")] page_image page_image)
    {
        if (ModelState.IsValid)
        {
            if (page_image.ImageFile != null)
            {
                string fileName = Path.GetFileNameWithoutExtension(page_image.ImageFile.FileName);
                string extension = Path.GetExtension(page_image.ImageFile.FileName);
                fileName = fileName + DateTime.Now.ToString("yymmssff") + extension;
                page_image.image = "/Uploads/page_images/" + fileName;

                fileName = Path.Combine(Server.MapPath("/Uploads/page_images"), fileName);
                page_image.ImageFile.SaveAs(fileName);
            }

            db.Entry(page_image).State = EntityState.Modified;
            db.SaveChanges();
            return RedirectToAction("Index");
        }
        ViewBag.category = new SelectList(db.page, "id", "title", page_image.category);
        return View(page_image);
    }

在这里，我可以编辑用户，但没有显示上一个图像，所以如果我单击submit而不加载一个新的图像，它将删除前一个图像。我要做的是编辑视图，我想让它显示图像的名称。你能带我去正确的方向吗？

Answer 1

如果page_image.Image是null，则获取先前的图像并分配

 if (page_image.ImageFile != null)
 {
       string fileName = Path.GetFileNameWithoutExtension(page_image.ImageFile.FileName);
       string extension = Path.GetExtension(page_image.ImageFile.FileName);
       fileName = fileName + DateTime.Now.ToString("yymmssff") + extension;
       page_image.image = "/Uploads/page_images/" + fileName;

       fileName = Path.Combine(Server.MapPath("/Uploads/page_images"), fileName);
       page_image.ImageFile.SaveAs(fileName);

 } else {
    // get existing image from database 
     var data = db.page_image.AsNoTracking().Where(b => b.id == page_image.id).FirstOrDefault();
     //assign to existing image
     page_image.image = data.image ;

 }
 db.Entry(page_image).State = EntityState.Modified;
 db.SaveChanges();
 return RedirectToAction("Index");

更新:由于dbcontext的相同实例，错误在这里抛出。您可以创建新实例以获取或执行以下操作。

var data = db.page_image.AsNoTracking().Where(b => b.id == page_image.id).FirstOrDefault();

或

using (var db2 = new YourDbContext())
{
    var data = db2.page_image.Where(b => b.id == page_image.id).FirstOrDefault();
}

Answer 2

问题是，因为您将视图模型保存到数据库中，所以您应该有一个DTO。无论如何，再次尝试从DB获取ImageFile，以防它提交了null。

if(page_image.ImageFile != null)
{
    //  your uploading logic
}
else
{
    var oldData = db.Set<page_image>().Where(x => x.id == page_image.id).FirstOrDefault();
    page_image.ImageFile = oldData.ImageFile;
}