ASP.NET 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，但没有显示以前的图像，因此如果我单击提交而不加载新图像，它将删除上一个图像。我要做的就是编辑视图，我希望它显示图像的名称。你能引导我走向正确的方向吗？

Answer 1

问题是因为您将视图模型按原样保存到数据库中，因此您应该有一个 DTO。无论如何，请尝试再次从数据库中获取ImageFile，以防它提交 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;
}

Answer 2

如果page_image.Imagenull则获取上一个图像并分配

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：由于数据库上下文的相同实例，此处抛出错误。您可以创建新实例进行提取或执行以下操作。

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();
}