在没有隐藏字段的情况下更新EF4实体上的单个属性

Question

我正在使用EF4(Db First),我有一个具有许多非可空属性的实体.

在编辑表单(Razor/MVC3)中,我想只允许编辑其中一个属性,而不允许编辑其他属性.

为了使其工作,我不得不为@Html.HiddenFor(...)我的其他每个属性放置无法为空的语句,否则我在SaveChanges()上收到错误.

是否有一种简单的方法可以在视图上隐藏ID,可以编辑的属性,然后只更新该属性？

Answer 1

在这种情况下,您需要做的就是将您正在编辑的实体的ID包含为隐藏字段以及您实际想要编辑的属性的文本字段:

@using (Html.BeginForm())
{
    @Html.HiddenFor(x => x.ID)
    @Html.EditorFor(x => x.PropertyYouWannaEdit)
    <button type="submit">Update</button>
}

然后在相应的控制器操作中,您可以从数据库中检索需要编辑的实体,更新需要编辑的属性的值并保存更改.

[HttpPost]
public ActionResult Update(SomeEntity model)
{
    SomeEntity entityToEdit = db.GetEntity(model.ID);
    entityToEdit.PropertyYouWannaEdit = model.PropertyYouWannaEdit;
    db.Update(entityToEdit);
    return RedirectToAction("Success");
}

但我个人会使用视图模型和AutoMapper来处理这种情况.所以我首先要设计一个表示我的视图要求的视图模型,并包括仅需要编辑的属性:

public class MyEntityViewModel
{
    public int ID { get; set; }
    public string Property1ToBeEdited { get; set; }
    public string Property2ToBeEdited { get; set; }
    ...
}

然后有相应的视图:

@model MyEntityViewModel
@using (Html.BeginForm())
{
    @Html.HiddenFor(x => x.ID)

    @Html.EditorFor(x => x.Property1ToBeEdited)
    @Html.EditorFor(x => x.Property2ToBeEdited)
    ...

    <button type="submit">Update</button>
}

最后是2个控制器动作(GET和POST):

public ActionResult Update(int id)
{
    // Fetch the domain model that we want to be edited from db
    SomeEntity domainModel = db.GetEntity(id);

    // map the domain model to a view model
    MyEntityViewModel viewModel = Mapper.Map<SomeEntity, MyEntityViewModel>(domainModel);

    // pass the view model to the view
    return View(viewModel);
}

[HttpPost]
public ActionResult Update(MyEntityViewModel model)
{
    if (!ModelState.IsValid)
    {
        // validation failed => redisplay view so that the user can fix the errors
        return View(model);
    }

    // fetch the domain entity that needs to be edited:
    SomeEntity entityToEdit = db.GetEntity(model.ID);

    // update only the properties that were part of the view model,
    // leaving the others intact
    Mapper.Map<MyEntityViewModel, SomeEntity>(model, entityToEdit);

    // persist the domain model
    db.Update(entityToEdit);

    // we are done   
    return RedirectToAction("Success");
}