Asp.net mvc 4 如何在编辑时保留varbinary类型的图像数据?
我有一个小的演示应用程序来处理存储在数据库中的二进制数据。相关代码见下文: 实体类:Asp.net mvc 4 如何在编辑时保留varbinary类型的图像数据?,asp.net-mvc-4,visual-studio-2012,binary-data,entity-framework-5,razor-2,Asp.net Mvc 4,Visual Studio 2012,Binary Data,Entity Framework 5,Razor 2,我有一个小的演示应用程序来处理存储在数据库中的二进制数据。相关代码见下文: 实体类: [HiddenInput(DisplayValue = false)] public int Id { get; set; } [Display(Name = "Full Name:")] public string Name { get; set; } [DataType(DataType.Upload)] [Display(Name = "Photo:"
[HiddenInput(DisplayValue = false)]
public int Id { get; set; }
[Display(Name = "Full Name:")]
public string Name { get; set; }
[DataType(DataType.Upload)]
[Display(Name = "Photo:")]
public byte[] ImageData { get; set; }
[HiddenInput(DisplayValue = false)]
public string ImageMimeType { get; set; }
[HttpGet]
public ActionResult Edit(int id)
{
var mensPlayer = _dataSource.MensPlayers.FirstOrDefault(p => p.Id == id);
return View(mensPlayer);
}
[HttpPost]
public ActionResult Edit(MensPlayer mensPlayer, HttpPostedFileBase image)
{
if (ModelState.IsValid)
{
//Added line below
_dataSource.ImageTemp(mensPlayerInDb, mensPlayer);
if (image != null)
{
mensPlayer.ImageMimeType = image.ContentType;
mensPlayer.ImageData = new byte[image.ContentLength];
image.InputStream.Read(mensPlayer.ImageData, 0, image.ContentLength);
}
//Added line below
mensPlayer.ImageData = mensPlayerInDb.ImageData;
//Save Player
_dataSource.Update(mensPlayer);
_dataSource.Save();
TempData["message"] = string.Format("{0} has been saved", mensPlayer.Name);
return RedirectToAction("Detail", "MensPlayer", new {id = mensPlayer.Id});
}
return View(mensPlayer);
}
public FileContentResult GetImage(int id)
{
var image = _dataSource.MensPlayers.FirstOrDefault(p => p.Id == id);
if (image != null)
{
return File(image.ImageData, image.ImageMimeType);
}
return null;
}
编辑操作:
[HiddenInput(DisplayValue = false)]
public int Id { get; set; }
[Display(Name = "Full Name:")]
public string Name { get; set; }
[DataType(DataType.Upload)]
[Display(Name = "Photo:")]
public byte[] ImageData { get; set; }
[HiddenInput(DisplayValue = false)]
public string ImageMimeType { get; set; }
[HttpGet]
public ActionResult Edit(int id)
{
var mensPlayer = _dataSource.MensPlayers.FirstOrDefault(p => p.Id == id);
return View(mensPlayer);
}
[HttpPost]
public ActionResult Edit(MensPlayer mensPlayer, HttpPostedFileBase image)
{
if (ModelState.IsValid)
{
//Added line below
_dataSource.ImageTemp(mensPlayerInDb, mensPlayer);
if (image != null)
{
mensPlayer.ImageMimeType = image.ContentType;
mensPlayer.ImageData = new byte[image.ContentLength];
image.InputStream.Read(mensPlayer.ImageData, 0, image.ContentLength);
}
//Added line below
mensPlayer.ImageData = mensPlayerInDb.ImageData;
//Save Player
_dataSource.Update(mensPlayer);
_dataSource.Save();
TempData["message"] = string.Format("{0} has been saved", mensPlayer.Name);
return RedirectToAction("Detail", "MensPlayer", new {id = mensPlayer.Id});
}
return View(mensPlayer);
}
public FileContentResult GetImage(int id)
{
var image = _dataSource.MensPlayers.FirstOrDefault(p => p.Id == id);
if (image != null)
{
return File(image.ImageData, image.ImageMimeType);
}
return null;
}
GetImage方法:
[HiddenInput(DisplayValue = false)]
public int Id { get; set; }
[Display(Name = "Full Name:")]
public string Name { get; set; }
[DataType(DataType.Upload)]
[Display(Name = "Photo:")]
public byte[] ImageData { get; set; }
[HiddenInput(DisplayValue = false)]
public string ImageMimeType { get; set; }
[HttpGet]
public ActionResult Edit(int id)
{
var mensPlayer = _dataSource.MensPlayers.FirstOrDefault(p => p.Id == id);
return View(mensPlayer);
}
[HttpPost]
public ActionResult Edit(MensPlayer mensPlayer, HttpPostedFileBase image)
{
if (ModelState.IsValid)
{
//Added line below
_dataSource.ImageTemp(mensPlayerInDb, mensPlayer);
if (image != null)
{
mensPlayer.ImageMimeType = image.ContentType;
mensPlayer.ImageData = new byte[image.ContentLength];
image.InputStream.Read(mensPlayer.ImageData, 0, image.ContentLength);
}
//Added line below
mensPlayer.ImageData = mensPlayerInDb.ImageData;
//Save Player
_dataSource.Update(mensPlayer);
_dataSource.Save();
TempData["message"] = string.Format("{0} has been saved", mensPlayer.Name);
return RedirectToAction("Detail", "MensPlayer", new {id = mensPlayer.Id});
}
return View(mensPlayer);
}
public FileContentResult GetImage(int id)
{
var image = _dataSource.MensPlayers.FirstOrDefault(p => p.Id == id);
if (image != null)
{
return File(image.ImageData, image.ImageMimeType);
}
return null;
}
显示图像:
@if (Model.ImageData != null) {
<div >
<img width="300" height="400" src="@Url.Action("GetImage", "MensPlayer",
new { Model.Id })" alt="Player Image"/>
</div>
}
我的问题是,每次我尝试编辑播放器时,都会从数据库中很好地检索到所有数据,但当我在编辑后点击save时,ImageData就会丢失,更像是用空值替换原始数据。就像,应用程序希望我在每次尝试编辑时重新上传图像一样
我能做些什么来清理这个?好吧,如果
image
是null
那么在你的实体mensPlayer.ImageData
是null
。稍后当您调用\u dataSource.Update(mensPlayer)
时,您将实体的状态设置为Modified
(至少我猜Update
只是将状态设置为Modified
),因此您告诉EF您也修改了图像(即将其设置为null
),EF将保存该更改
为了解决这个问题,您可以先从数据库加载包含图像的实体
var mensPlayerInDb = context.MensPlayers.Find(mensPlayer.Id);
mensPlayer.ImageData = mensPlayerInDb.ImageData; // save the ImageData
// copy changed values to loaded entity and save it, ImageData is unchanged
context.Entry(mensPlayerInDb).CurrentValues.SetValues(mensPlayer);
context.SaveChanges();
…或者您可以尝试:
context.Entry(mensPlayer).State = EntityState.Modified;
context.Entry(mensPlayer).Property(m => m.ImageData).IsModified = false;
后一种方法不适用于EF<5.0(因为一旦实体被标记为Modified
,禁止将属性的Modified
状态设置为false
),但它应该适用于EF 5
您需要将其中一个解决方案集成到您的
\u数据源
服务类中,可能需要引入新方法,因为它与您的常规更新
方法不兼容。对不起,我在生活中遇到了一些问题,但我又回来了。第二个选项看起来很容易实现,但由于第一行将所有内容都设置为“修改”,因此出现了一个错误。在第一个选项中,我了解代码的归档内容,但在实现解决方案时遇到了困难。查看并建议我是否在正确的轨道上。@KomengeMwandila:但是您没有在任何地方使用ImageTemp
,也没有从数据库加载原始图像,是吗?我已经更新了编辑操作。但有一个问题,这行代码是否必要:var mensplayerdb=context.MensPlayers.Find(mensPlayer.Id)代码>当我有这行代码时:var model=\u dataSource.MensPlayers.Single(p=>p.Id==Id)代码>在我的HttpGet中?我很难理解那行代码中使用的Find属性?当我build@KomengeMwandila:您也可以使用Single
。您没有Find
,因为在您的_数据源MensPlayer
中是IQueryabl
而不是DbSet
。