使用Entity Framework检测控制器中模型属性的状态更改

Question

我有一个或多或少的标准模型:

public class Project {
  public int ID { get; set; }
  //... some more properties

  public DateTime StartDate { get; set; }
  public int Duration { get; set; }
}

如果用户修改StartDate或投影Duration,我必须调用函数来更新模拟.为了实现这一点,我想检测字段StartDate和Duration控制器内的状态变化.

像这样的东西:

if(project.StartDate.stateChange() || project.Duration.stateChange())

以下是Controller Method的示例:

[HttpPost]
public ActionResult Edit(Project project)
{
    if (ModelState.IsValid)
    {
        if(project.StartDate.stateChange() || project.Duration.stateChange())
            doSomething();

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

任何想法,我怎样才能做到这一点？

Answer 1

我相信你可以将编辑过的实体与从数据库中读取的原始实体进行比较.

就像是:

public ActionResult Edit(Project project)
{
    if (ModelState.IsValid)
    {
        var original = db.Find(project.ID);
        bool changed = original.StartDate != project.StartDate || original.Duration != project.Duration;
        if (changed)
        {
            original.StartDate = project.StartDate;
            original.Duration = project.Duration;
            doSomething();
            db.Entry(original).CurrentValues.SetValues(project);
            db.SaveChanges();
        }
    }
    return View(project);
}

Answer 2

您可以通过ViewBag携带旧值来解决它.

在行动:

public ActionResult Edit(int? id)
{
    //...Your Code
    ViewBag.OrigStartDate = project.StartDate;
    ViewBag.OrigDuration = project.Duration;
    return View(project);
}

向View添加隐藏元素

...
@Html.Hidden("OrigStartDate", (DateTime)ViewBag.OrigStartDate)
@Html.Hidden("OrigDuration", (int)ViewBag.OrigDuration)
...

将这些参数添加到post方法并检查它们的更改

[HttpPost]
public ActionResult Edit(DateTime OrigStartDate, int OrigDuration)
{
    if (ModelState.IsValid)
    {
        if (OrigStartDate != project.StartDate || OrigDuration != project.Duration)
            doSomething();

        db.Entry(project).State = EntityState.Modified;
        db.SaveChanges();
        return RedirectToAction("Index");
    }
    ViewBag.FileTypeId = new SelectList(db.FileTypes, "Id", "TypeName", dbinfo.FileTypeId);
    return View(project);
}