Asp.net mvc 3 如何在mvc3 razor中与模型一起使用DropDownList for

我想在我的视图中使用Lower属性和dropdownbox。 我怎么能？ 我尝试了很多方法，但是
请帮忙

public IEnumerable<SelectListItem> Topic
{
    get
    {
        return  new[]
        {
            new SelectListItem { Value = "1", Text = "Science", Selected=true },
            new SelectListItem { Value = "2", Text = "History" },
            new SelectListItem { Value = "3", Text = "Physics" },
        };
    }
}

public SelectList Topic
            {
                get
                {
                    return new SelectList(
                      new List<SelectListItem> {
                      new SelectListItem { Value = "1", Text = "Science", Selected = true },
                      new SelectListItem { Value = "2", Text = "History" },
                      new SelectListItem { Value = "3", Text = "Physics" }
                    },"Value","Text"
                    );
                }
            }


public int selectedType {get;set;}

公共IEnumerable主题
{
得到
{
返回新的[]
{
新建SelectListItem{Value=“1”，Text=“Science”，Selected=true}，
新建SelectListItem{Value=“2”，Text=“History”}，
新建SelectListItem{Value=“3”，Text=“Physics”}，
};
}
}

您尚未添加视图代码

public SelectList Topic
            {
                get
                {
                    return new SelectList(
                      new List<SelectListItem> {
                      new SelectListItem { Value = "1", Text = "Science", Selected = true },
                      new SelectListItem { Value = "2", Text = "History" },
                      new SelectListItem { Value = "3", Text = "Physics" }
                    },"Value","Text"
                    );
                }
            }


public int selectedType {get;set;}

基本上，您需要向视图中添加一个

@model

，如下所示：

@model MySampleApplication.Models.ModelName

public class MyModel
{
public IEnumerable<SelectListItem> Topic
{
    get
    {
        return  new[]
        {
            new SelectListItem { Value = "1", Text = "Science", Selected=true },
            new SelectListItem { Value = "2", Text = "History" },
            new SelectListItem { Value = "3", Text = "Physics" },
        };
    }
}
}

public ActionResult Index() 
{
   MyModel model=new MyModel();
   return View(model);
}

public SelectList Topic
            {
                get
                {
                    return new SelectList(
                      new List<SelectListItem> {
                      new SelectListItem { Value = "1", Text = "Science", Selected = true },
                      new SelectListItem { Value = "2", Text = "History" },
                      new SelectListItem { Value = "3", Text = "Physics" }
                    },"Value","Text"
                    );
                }
            }


public int selectedType {get;set;}

在您看来，您应该这样访问：

@Html.DropdownListFor(m=>m.Topic, Model.Topic)

public SelectList Topic
            {
                get
                {
                    return new SelectList(
                      new List<SelectListItem> {
                      new SelectListItem { Value = "1", Text = "Science", Selected = true },
                      new SelectListItem { Value = "2", Text = "History" },
                      new SelectListItem { Value = "3", Text = "Physics" }
                    },"Value","Text"
                    );
                }
            }


public int selectedType {get;set;}

斯科特·艾伦

public SelectList Topic
            {
                get
                {
                    return new SelectList(
                      new List<SelectListItem> {
                      new SelectListItem { Value = "1", Text = "Science", Selected = true },
                      new SelectListItem { Value = "2", Text = "History" },
                      new SelectListItem { Value = "3", Text = "Physics" }
                    },"Value","Text"
                    );
                }
            }


public int selectedType {get;set;}

希望能有帮助

public SelectList Topic
            {
                get
                {
                    return new SelectList(
                      new List<SelectListItem> {
                      new SelectListItem { Value = "1", Text = "Science", Selected = true },
                      new SelectListItem { Value = "2", Text = "History" },
                      new SelectListItem { Value = "3", Text = "Physics" }
                    },"Value","Text"
                    );
                }
            }


public int selectedType {get;set;}

---

编辑

public SelectList Topic
            {
                get
                {
                    return new SelectList(
                      new List<SelectListItem> {
                      new SelectListItem { Value = "1", Text = "Science", Selected = true },
                      new SelectListItem { Value = "2", Text = "History" },
                      new SelectListItem { Value = "3", Text = "Physics" }
                    },"Value","Text"
                    );
                }
            }


public int selectedType {get;set;}

假设您有这样的模型类：

@model MySampleApplication.Models.ModelName

public class MyModel
{
public IEnumerable<SelectListItem> Topic
{
    get
    {
        return  new[]
        {
            new SelectListItem { Value = "1", Text = "Science", Selected=true },
            new SelectListItem { Value = "2", Text = "History" },
            new SelectListItem { Value = "3", Text = "Physics" },
        };
    }
}
}

public ActionResult Index() 
{
   MyModel model=new MyModel();
   return View(model);
}

public SelectList Topic
            {
                get
                {
                    return new SelectList(
                      new List<SelectListItem> {
                      new SelectListItem { Value = "1", Text = "Science", Selected = true },
                      new SelectListItem { Value = "2", Text = "History" },
                      new SelectListItem { Value = "3", Text = "Physics" }
                    },"Value","Text"
                    );
                }
            }


public int selectedType {get;set;}

试试这个

public SelectList Topic
            {
                get
                {
                    return new SelectList(
                      new List<SelectListItem> {
                      new SelectListItem { Value = "1", Text = "Science", Selected = true },
                      new SelectListItem { Value = "2", Text = "History" },
                      new SelectListItem { Value = "3", Text = "Physics" }
                    },"Value","Text"
                    );
                }
            }


public int selectedType {get;set;}

型号

public SelectList Topic
            {
                get
                {
                    return new SelectList(
                      new List<SelectListItem> {
                      new SelectListItem { Value = "1", Text = "Science", Selected = true },
                      new SelectListItem { Value = "2", Text = "History" },
                      new SelectListItem { Value = "3", Text = "Physics" }
                    },"Value","Text"
                    );
                }
            }


public int selectedType {get;set;}

---

您是否可以显示您为reply dear而尝试Hanx的代码，但它给出了相同的错误System.NullReferenceException:对象引用未设置为对象的实例。您是否可以显示控制器代码？您是否将模型作为返回视图（模型）传递给视图？不，我没有传递任何内容。实际上，这是我的控制器的一个创建操作。我只想在下拉列表中绑定预定义数据。如果您希望我们帮助您，您应该提供更多详细信息，如视图标记和控制器代码。实际上，我只想在Dropdownlist中使用下面提到的模型。我在这里有get属性，所以不需要从控制器公共选择列表主题获取数据{获取{返回新的SelectList（新列表{new SelectListItem{Value=“1”，Text=“Science”，Selected=true}，新SelectListItem{Value=“2”，Text=“History”}，新SelectListItem{Value=“3”，Text=“Physics”}}）；}}请显示您的控制器代码。您是否实例化了模型类并将该对象传递给视图？我没有。我的控制器就像public ActionResult Index（）{retuer view（）}但是我的模型在Get中有数据。我认为它应该可以工作。请帮助。我可以看到数据。即使我在示例应用程序中尝试过，它也工作得很好。请尝试调试并检查您的Topic属性是否在模型对象中填充了下拉值