我正在通过webgrid显示数据。 webgrid有文本框和下拉列表，显示每个学生的姓名，州，城市等。我的代码正在运行，但每个学生都显示错误的选定城市。我手动填充我的视图模型，以便于测试。在这里，我正在粘贴我的代码。如果可能请看看，让我知道错误的城市显示的原因。在代码中要改变什么。 我的完整代码在这里
我的dotnet小提琴链接https://dotnetfiddle.net/BrKBx1
请不要告诉我更改模型类设计代码。
public class MainViewModel
{
public List<Student> Students { get; set; }
public int SelectedState { get; set; }
public int SelectedCity { get; set; }
}
public class Student
{
public int ID { get; set; }
public string Name { get; set; }
public int StateID { get; set; }
public int CityID { get; set; }
public List<States> States { get; set; }
public List<Cities> Cities { get; set; }
}
public class States
{
public int ID { get; set; }
public string Name { get; set; }
}
public class Cities
{
public int ID { get; set; }
public string Name { get; set; }
public int StateID { get; set; }
}
public ActionResult Index()
{
MainViewModel oVm = new MainViewModel()
{
Students = new List<Student>() {
new Student
{
ID=1,
Name="JoyDev",
StateID=1,
CityID=1,
States=new List<States>()
{
new States
{
ID=1,
Name="WestBengal",
},
new States
{
ID=2,
Name="Bihar",
},
new States
{
ID=3,
Name="Orrisa",
}
},
Cities=new List<Cities>()
{
new Cities
{
ID=1,
Name="Alipur"
},
new Cities
{
ID=2,
Name="Asansol"
},
new Cities
{
ID=3,
Name="Andul"
}
}
},
//***********
new Student
{
ID=2,
Name="Mukti",
StateID=2,
CityID=4,
States=new List<States>()
{
new States
{
ID=1,
Name="WestBengal",
},
new States
{
ID=2,
Name="Bihar",
},
new States
{
ID=3,
Name="Orrisa",
}
},
Cities=new List<Cities>()
{
new Cities
{
ID=4,
Name="Janpur"
},
new Cities
{
ID=5,
Name="Madhubani"
},
new Cities
{
ID=6,
Name="Kanti"
}
}
},
//***********
new Student
{
ID=3,
Name="Somnath",
StateID=3,
CityID=9,
States=new List<States>()
{
new States
{
ID=1,
Name="WestBengal",
},
new States
{
ID=2,
Name="Bihar",
},
new States
{
ID=3,
Name="Orrisa",
}
},
Cities=new List<Cities>()
{
new Cities
{
ID=7,
Name="Chandapur"
},
new Cities
{
ID=8,
Name="Dhankauda"
},
new Cities
{
ID=9,
Name="Konarak"
}
}
}
}
};
return View(oVm);
}
@model BuildTable.Models.MainViewModel
@{
ViewBag.Title = "Test Grid";
}
@{
WebGrid grid = new WebGrid(null);
grid.Bind(Model.Students);
}
@grid.GetHtml(
tableStyle: "webgrid-table",
headerStyle: "webgrid-header",
footerStyle: "webgrid-footer",
alternatingRowStyle: "webgrid-alternating-row",
selectedRowStyle: "webgrid-selected-row",
rowStyle: "webgrid-row-style",
mode: WebGridPagerModes.All,
firstText: "<<",
previousText: "<",
nextText: ">",
lastText: ">>",
numericLinksCount: 5,
columns:
grid.Columns
(
grid.Column(columnName: "ID", header: "ID", format: @<text>@item.ID</text>,style:"SmallCols"),
grid.Column(columnName: "FirstName", header: "First Name", format: @<text><input type="text" id="txtFirstName" value="@item.Name" class="edit-mode" /></text>,style:"NameColWidth" ),
//grid.Column(columnName: "StateName", header: "State Name", format: @<text>@Html.DropDownListFor(x => x.SelectedState, new SelectList(Model.Students[1].States, "ID", "Name", Model.SelectedState = item.StateID), "-- Select States--", new { id = "cboState", @class = "edit-mode" })</text>,style:"NameColWidth"),
grid.Column(columnName: "StateName", header: "State Name", format: @<text>@Html.DropDownListFor(x => x.SelectedState, new SelectList(Model.Students.SelectMany(x => x.States).Where(x => x.StateID == item.StateID), "ID", "Name", Model.SelectedState = item.StateID), "-- Select States--", new { id = "cboState", @class = "edit-mode" })</text>,style:"NameColWidth"),
grid.Column(columnName: "CityName", header: "City Name", format: @<text>@Html.DropDownListFor(x => x.SelectedCity, new SelectList(Model.Students.SelectMany(x => x.Cities).Where(x => x.ID == item.StateID), "ID", "Name", Model.SelectedCity = item.CityID), "-- Select City--", new { id = "cboCity", @class = "edit-mode" })
</text>,style:"NameColWidth")
))
我们不能这样过滤(Model.Students.SelectMany(x => x.Cities).Where(x => x.StateID == item.StateID)
上面的代码返回每个学生的所有城市数据，我在那里根据州id过滤城市。如果这不对
代码，然后建议我写什么来实现相同。感谢
答案 0 :(得分：1)
您从未设置任何城市的StateID，因此如果您按StateID == item.StateID过滤，则永远不会匹配。
在你的控制器中，你需要这样的东西：
Cities = new List<Cities>()
{
new Cities
{
ID = 4,
StateID = 1, // add this!
Name = "Janpur"
},
new Cities
{
ID = 5,
StateID = 2, // add this!
Name = "Madhubani"
},
new Cities
{
ID = 6,
StateID = 3, // add this!
Name = "Kanti"
}
}
另外，我建议您将SelectLists放入视图模型，而不是在视图中创建它们。这将使您的代码更易于阅读，从概念上讲，SelectList实际上是一种支持视图的模型，它不是视图本身。
这是一个更新的小提琴：https://dotnetfiddle.net/UYpO9m
答案 1 :(得分：0)
因为您的Where来电是 SelectMany之后的。此时，您拥有的只是Cities的集合，因此当您按x.ID == item.StateID过滤时，您只说Cities个Cities.ID等于item.StateID的实例}。没有，根据您的测试数据，所以没有返回任何内容。更有可能的是，您只需要在Where来电之前将SelectMany电话移至，然后将表达式更改为x.StateID == item.StateID。