我是ASP.net MVC的新手,我使用viewmodel而不是viewbags填充我的下拉菜单,因为我看到大多数人推荐他们.我有一个光滑的用户界面,可以进行级联下拉和自动填充(此处未显示),但我似乎无法将我的数据保存回数据库.
楷模：
public partial class Car
{
public int CarID { get; set; }
public string CarName { get; set; }
public int ModelID { get; set; }
public int ManufacturerID { get; set; }
public int CarColorID { get; set; }
public Nullable<decimal> Price { get; set; }
public string Description { get; set; }
public virtual CarColor CarColor { get; set; }
public virtual Manufacturer Manufacturer { get; set; }
public virtual CarModel CarModel { get; set; }
}
public partial class CarColor
{
public CarColor()
{
this.Cars = new HashSet<Car>();
}
public int ColorID { get; set; }
public string ColorName { get; set; }
public virtual ICollection<Car> Cars { get; set; }
}
public partial class CarModel
{
public CarModel()
{
this.Cars = new HashSet<Car>();
}
public int CarModelID { get; set; }
public int ManufacturerID { get; set; }
public string CarModelName { get; set; }
public virtual ICollection<Car> Cars { get; set; }
public virtual Manufacturer Manufacturer { get; set; }
}
public partial class Manufacturer
{
public Manufacturer()
{
this.Cars = new HashSet<Car>();
this.Manufacturer1 = new HashSet<Manufacturer>();
this.CarModels = new HashSet<CarModel>();
}
public int ManufacturerID { get; set; }
public string ManufacturerName { get; set; }
public Nullable<int> ParentID { get; set; }
public virtual ICollection<Car> Cars { get; set; }
public virtual ICollection<Manufacturer> Manufacturer1 { get; set; }
public virtual Manufacturer Manufacturer2 { get; set; }
public virtual ICollection<CarModel> CarModels { get; set; }
}
视图模型：
public class AnotherTestviewmodel { public Car car { get; set; } public IEnumerable<SelectListItem> CarModels { get; set; } public IEnumerable<SelectListItem> Manufacturers { get; set; } public IEnumerable<SelectListItem> CarColors { get; set; } }
控制器：
public ActionResult Create()
{
var model = new AnotherTestviewmodel();
using (new CarTestEntities())
{
model.CarModels = db.CarModels.ToList().Select(x => new SelectListItem
{
Value = x.CarModelID.ToString(),Text = x.CarModelName
});
model.Manufacturers = db.Manufacturers.ToList().Select(x => new SelectListItem
{
Value = x.ManufacturerID.ToString(),Text = x.ManufacturerName
});
model.CarColors = db.CarColors.ToList().Select(x => new SelectListItem
{
Value = x.ColorID.ToString(),Text = x.ColorName
});
}
return View(model);
}
//
// POST: /AnotherTest/Create
[HttpPost]
public ActionResult Create(AnotherTestviewmodel model)
{
if (ModelState.IsValid)
{
db.Entry(model).State = EntityState.Modified;
db.SaveChanges();
return RedirectToAction("Details","AnotherTestviewmodel",new { id = model.car.CarID });
}
return View();
}
我看到了一些使用Automapper的建议,因为EntityState.Modified不起作用,但我不知道如何配置它,因为使用下面的代码不起作用.
Mapper.CreateMap<AnotherTestviewmodel,Car>(); Mapper.CreateMap<Car,AnotherTestviewmodel>(); var newCar = Mapper.Map<AnotherTestviewmodel,Car>(model);
有任何想法吗？
解决方法
您的视图模型不应与数据库交互.视图模型应仅用于表示层(用户界面) – 因此称为“视图”模型.您应该有另一个与数据库交互的模型(数据模型).然后,您应该有一些类型的服务层来处理视图模型和数据模型之间的转换(反之亦然).您的数据模型是由Entity Framework生成的模型(我假设您正在使用它).要处理数据库更新,您需要实例化数据上下文,从数据库中获取数据实体,对该实体进行更改,并在该数据上下文中调用保存更改.数据上下文将跟踪实体的所有更改,并在您调用“保存更改”时对数据库应用必要的更改.
例：
例：
public void UpdateCar(Carviewmodel viewmodel) { using (DataContext context = new DataContext()) { CarEntity dataModel = context.CarEntities.where(x => x.Id == viewmodel.Id).First(); dataModel.Name = viewmodel.Name; dataModel.Type = viewmodel.Type; context.SaveChanges(); } }
在此示例中,上下文将跟踪对“dataModel”的任何更改.调用“context.SaveChanges”时,这些更改将自动应用于数据库.