为具有一个附加属性的关联类显示 Html.ListBoxFor

Question

编辑和部分回答：我不知道如何显示多列，但如果不是这样，您必须在 Call 类中覆盖 ToString。

---

我有一个班级Person（他们接电话）：

 public class Person {
        public int Id { get; set; }

        [DisplayName("First Name")]
        public string FirstName { get; set; }

        [DisplayName("Last Name")]
        public string LastName { get; set; }

        public virtual ICollection<Call> ReceivedCalls { get; set; }
    }

一个班级ApplicationUser（他们打电话）：

 public class ApplicationUser : IdentityUser {
        public virtual ICollection<Call> MadeCalls { get; set; }
 }

以及它们之间的关联类Call:

 public class Call {
        public int Id { get; set; }
        public virtual Person Callee { get; set; }
        public virtual ApplicationUser Caller { get; set; }
        public DateTime TimeStamp { get; set; } //Additional Attribute
    }

他们在数据库中合作得很好。但是我在使用@Html.ListBoxFor 方法来显示一个ListBox 时遇到了麻烦，其中的每一行都会显示谁来电以及何时调用：Caller.UserName | Call.TimeStamp 用于收到的每个电话（由人员）。

我想在 Razor View 中显示那些强类型化的信息：

@model WebApplication2.Models.Person

我试过这个：

@Html.ListBoxFor(m => m.ReceivedCalls, new MultiSelectList(Model.ReceivedCalls, "TimeStamp" ), new {Multiple = "multiple"})

它正在被翻译（输出 HTML）为：

<select Multiple="multiple" id="ReceivedCalls" multiple="multiple" name="ReceivedCalls"><option selected="selected">System.Data.Entity.DynamicProxies.Call_2FC3E1C25C19BA21E6B64CAB2894602434775435359AAB76E58C6F8411451A49</option>
<option selected="selected">System.Data.Entity.DynamicProxies.Call_2FC3E1C25C19BA21E6B64CAB2894602434775435359AAB76E58C6F8411451A49</option>
</select>

它看起来像：

问题：如何在每行显示谁来电以及何时调用的 ListBox：Caller.UserName | Call.TimeStamp 显示每个接听电话（按人）。

---

**编辑：**

有一些语法错误：

        // Create collection of anonymous objects (adjust format to suit your needs)
        var receivedCalls = person.ReceivedCalls.Select(c => new {
            ID = c.Id,
            DisplayName = string.Format("{0}: {1:D}", c.Caller.UserName, c.TimeStamp)
        });
        // Initialise view model
        PersonVM model = new PersonVM();
        // Map properties from person to model

        // Assign select list
        model.CallList = new MultiSelectList(receivedCalls, "ID", "DisplaName");

查看：

@Html.ListBoxFor(m => m.ReceivedCalls, new MultiSelectList(Model.ReceivedCalls))

---

如果我只是覆盖 Call 中的 ToString，结果完全一样：

   public override string ToString() {
            if (Caller != null)
                return Caller.UserName + " called at " + TimeStamp;
            return "called at " + TimeStamp;
        }

@Html.ListBoxFor(m => m.ReceivedCalls, new MultiSelectList(Model.ReceivedCalls, "TimeStamp"), new { Multiple = "multiple", style = "width: 100%;" })

所以我认为它仍然依赖于 ToString。

Answer 1

你应该创建一个视图模型来显示和绑定你的属性

查看模型

public class PersonVM
{
  public int Id { get; set; }
  public string FirstName { get; set; }
  public string LastName { get; set; }
  public int[] ReceivedCalls { get; set; } // this will bind to the selected calls
  public MultiSelectList CallList { get; set; } // to display the calls   
}

控制器

// Create collection of anonymous objects (adjust format to suit your needs)
var receivedCalls = person.ReceivedCalls.Select(c => new 
{
  ID = c.ID,
  DisplayName = string.Format("{0}: {1:D}", c.Callee.UserName, c.TimeStamp)
}
// Initialise view model
PersonVM model = new PersonVM();
// Map properties from person to model
...
// Assign select list
model.CallList  = new MultiSelectList(receivedCalls , "ID", "DisplaName");
return View(model);

查看

@model YourAssembly.PersonVM
....
@Html.ListBoxFor(m => m.ReceivedCalls, Model.CallList)

编辑

根据 OP 的要求，即最近调用的集合仅用于显示（不用于编辑），调整视图以使用无序列表（基于 OP 的模型，而不是上面建议的视图模型）

@model WebApplication2.Models.Person
....
<ul>
  @foreach(var call in Model.ReceivedCalls)
  {
    <li>@call</li> // this will use the .ToString() method
  }
</ul>

然后根据需要设置元素的样式，例如设置固定高度并使其可滚动且不带项目符号

<style>
  ul {
    height:60px;
    overflow-y:scroll;
  }
  li {
    list-style:none;
  }
</style>