如何显示嵌套列表并维护MVC模式? [英] How to display nested list and maintain MVC pattern?

问题描述

尝试使用MVC 6和EF代码优先设计显示嵌套列表.我正在使用

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现在，我想在每个位置下方显示子位置，如下图所示.用户可以添加新位置或绑定到该位置的子位置.

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显示位置列表很简单: return View(_context.Location.ToList());

要显示嵌套的子位置列表，我应该在控制器或视图中进行工作吗?

我希望我可以像下面这样使用视图，但是 item.Sublocations 是 null ，原因是我不确定，因为其中包含数据数据库.

  @foreach(模型中的变量项){< tr>< td> @ Html.DisplayFor(modelItem => item.LocationName)</td></tr>@foreach(item.Sublocations中的SubLocation itm){< tr>< td> @ itm.SubLocationName</td></tr>}} 

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我尝试在控制器中创建查询，但是无法使用外键进行比较.

  var test =(从_context.SubLocation中的m其中m.LocationID == curLocID<-m.LocationID不可用选择m.SubLocationName).ToList(); 

即使我可以使用LocationID，也不确定如何将当前View(curLocID)从视图"发送回控制器.我想我需要一个辅助方法，但是我开始盘算了.

如何维护适当的MVC并显示主类的子类中的嵌套列表?

解决方案

您应该考虑将 LocationID 属性添加到您的 SubLocation 类中，该属性将是 Location 表.

 公共类SubLocation{public int ID {get;放;}公共字符串SubLocationName {get;放;}public int LocationID {set; get;}} 

现在，查询位置.位置具有 SubLocations 属性，因此您的视图应该可以正常工作.

  var location = _context.Locations.Include(s => s.SubLocations).ToList();返回View(位置); 

Attempting to display nested list using MVC 6 and EF code first design. I'm using this Tutorial to get me started with MVC and am trying to take it to another level.

Classes:

public class Location
{
    [Key]
    public int ID { get; set; }
    public string LocationName { get; set; }
    public ICollection<SubLocation> Sublocations { get; set; }
    }
}

public class SubLocation
{
    public int ID { get; set; }
    public string SubLocationName { get; set; }
}

Running dnx ef database update sets up my EF database correctly and assigns a foreign key to LocationID under SubLocation.

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Now I want to display Sub Locations under each Location like the following image. The user can add new locations or sub locations tied to a location.

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Displaying the list of locations is simple: return View(_context.Location.ToList());

To display the nested list of sub-locations, should I do the work in the controller or view?

I was hoping I could just use the view like the following but item.Sublocations is null for a reason that I'm not sure of since there is data in the database.:

@foreach (var item in Model) {
  <tr>
    <td>@Html.DisplayFor(modelItem => item.LocationName)</td>
  </tr>

  @foreach (SubLocation itm in item.Sublocations)
  {
    <tr>
        <td>@itm.SubLocationName</td>
    </tr>
  }
}

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I've tried creating a query in the controller but the foreign key isn't available to compare against.

var test = (from m in _context.SubLocation
            where m.LocationID == curLocID   <-- m.LocationID isn't available
            select m.SubLocationName
            ).ToList();  

Even if I could use the LocationID I'm not sure how to send the current Location (curLocID) from the View back to the controller. I think I need a helper method but I'm starting to go in circles.

How can I maintain proper MVC and display nested list from a subclass of my main class?

解决方案

You should consider adding a LocationID property to your SubLocation class which will be the foreign key to the Location table.

public class SubLocation
{
    public int ID { get; set; }
    public string SubLocationName { get; set; }
    public int LocationID { set;get;}
}

Now, query the locations. Location has a SubLocations property,so your view should work fine.

var locations = _context.Locations.Include(s=>s.SubLocations).ToList();
return View(locations);

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