如何设置默认值从模型ASP.NET MVC的DropDownList [英] How to set default value for ASP.NET MVC DropDownList from model

问题描述

我在MVC新。所以我下拉列表填充这样

i am new in mvc. so i populate dropdown this way

public ActionResult New()
{
    var countryQuery = (from c in db.Customers
                        orderby c.Country ascending
                        select c.Country).Distinct();
    List<SelectListItem> countryList = new List<SelectListItem>();
    string defaultCountry = "USA";
    foreach(var item in countryQuery)
    {
        countryList.Add(new SelectListItem() {
                        Text = item, 
                        Value = item, 
                        Selected=(item == defaultCountry ? true : false) });
    }
    ViewBag.Country = countryList;
    ViewBag.Country = "UK";
    return View();       
}

@Html.DropDownList("Country", ViewBag.Countries as List<SelectListItem>)

我想知道我怎么可以填充从模型下拉菜单，也可以设置默认值。任何样品code将是很大的帮助。谢谢

i like to know how can i populate dropdown from model and also set default value. any sample code will be great help. thanks

推荐答案

嗯，这是不这样做的好方法。

Well this is not a great way to do this.

创建一个视图模型，将持有你想在视图中呈现的一切。

Create a ViewModel that will hold everything you want to be rendered at the view.

public class MyViewModel{

  public List<SelectListItem> CountryList {get; set}
  public string Country {get; set}

  public MyViewModel(){
      CountryList = new List<SelectListItem>();
      Country = "USA"; //default values go here
}

你需要的数据填充它。

Fill it with the data you need.

public ActionResult New()
{
    var countryQuery = (from c in db.Customers
                        orderby c.Country ascending
                        select c.Country).Distinct();
    MyViewModel myViewModel = new MyViewModel ();

    foreach(var item in countryQuery)
    {
        myViewModel.CountryList.Add(new SelectListItem() {
                        Text = item, 
                        Value = item
                        });
    }
    myViewModel.Country = "UK";



    //Pass it to the view using the `ActionResult`
    return ActionResult( myViewModel);
}

目前来看，宣布这种观点是使用下面一行在文件的顶部期待着与类型MyViewModel模型

At the view, declare that this view is expecting a Model with type MyViewModel using the following line at the top of the file

@model namespace.MyViewModel 

和随时为你讨好你可以使用模型

And at anytime you may use the Model as you please

@Html.DropDownList("Country", Model.CountryList, Model.Country)

这篇关于如何设置默认值从模型ASP.NET MVC的DropDownList的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！