为什么不是MVC绑定我的嵌套集合？

Question

如果有几个linqTOsql对象，我试图通过窗体进行编辑。

首先，有个Stream类：

[Table] 
public class Stream 
{ 
    [HiddenInput(DisplayValue = false)] 
    [Column(IsPrimaryKey = true, IsDbGenerated = true, AutoSync = AutoSync.OnInsert)] 
    public long StreamID { get; set; } 

    /*other properties removes for brevity*/ 

    // relationship (one stream to many Stream2FieldTypes) 
    // uses EntitySet<Stream2FieldTypes> and OtherKey for the FK in Stream2FieldTypes 
    private EntitySet<Stream2FieldTypes> _Stream2FieldTypes; 
    [System.Data.Linq.Mapping.Association(Storage = "_Stream2FieldTypes", OtherKey = "StreamID")] 
    public EntitySet<Stream2FieldTypes> Stream2FieldTypes 
    { 
     get { return this._Stream2FieldTypes; } 
     set { this._Stream2FieldTypes.Assign(value); } 
    } 

} 

然后有Stream2FieldTypes类：

[Table] 
public class Stream2FieldTypes 
{ 
    [Column(IsPrimaryKey = true, IsDbGenerated = true, AutoSync = AutoSync.OnInsert)] 
    public long s2fID { get; set; } 

    /*other properties removed for brevity*/ 

    [Column] 
    public long StreamID { get; set; }  // FK 




    // relationship (one Stream2FieldTypes to Streams) 
    private EntitySet<Stream> _Stream; 
    [Association(Storage = "_Stream", ThisKey = "StreamID")] 
    public EntitySet<Stream> Stream 
    { 
     get { return this._Stream; } 
     set { this._Stream.Assign(value); } 
    } 
} 

我用linqTOsql库来获得这些对象，并将它们发送到这样的观点：

public ActionResult StreamEdit(long id) 
    { 
     Genesis.Domain.Entities.Stream stream = genesisRepository.Streams.FirstOrDefault(x => x.StreamID == id); 

     return View(stream); 
    } 

所有东西都发送到视图没有问题...但是当视图上的表单被提交时，Stream.Stream2FieldTypes由于某种原因而丢失。我赶上表单提交这个动作：

[HttpPost] 
    public ActionResult StreamEdit(long id, Genesis.Domain.Entities.Stream form) 
    { 

      return View(form); 
    } 

和View是没有Stream2FieldTypes集合。

的观点写Stream2FieldTypes这样的：

<% for (int i = 0; i < (Model.Stream2FieldTypes != null ? Model.Stream2FieldTypes.Count() : 0); i++) %> 
<% { %> 
    <div class="ListItem"> 
     Label: <%: Html.EditorFor(x => x.Stream2FieldTypes[i].s2fLabel, new { style="width:100px" })%> 
     Required: <%: Html.EditorFor(x => x.Stream2FieldTypes[i].s2fIsRequired)%> 
     Field Type ID": <%: Html.EditorFor(x => x.Stream2FieldTypes[i].FieldTypeID, new { style="width:20px;" })%> 
     Stream ID: <%: Html.EditorFor(x => x.Stream2FieldTypes[i].StreamID) %> 
</div> 
<% } %> 

为什么没有在MVC默认模型绑定正确地结合嵌套集合？

Answer 1

我会建议你使用POCO视图模型而不是那些混乱的模型类。他们不适应观点，很难与之合作。试图绑定到LINQ特定的集合，如EntitySet<T>不是一个好主意。这种使用编辑模板的方式实际上可能会起作用，但即使这种方法奏效，在介绍适当的视图模型之前也应该考虑它是一种临时解决方案。

在你的主观点与此更换循环：

<%: Html.EditorFor(x => x.Stream2FieldTypes) %> 

，然后添加一个强类型的~/Views/Home/EditorTemplates/Stream2FieldTypes.ascx局部视图：

<%@ Control 
    Language="C#" 
    Inherits="System.Web.Mvc.ViewUserControl<SomeNs.Stream2FieldTypes>" 
%> 
<div class="ListItem"> 
    Label: 
    <%: Html.EditorFor(x => x.s2fLabel, new { style="width:100px" }) %> 

    Required: 
    <%: Html.EditorFor(x => x.s2fIsRequired) %> 

    Field Type ID: 
    <%: Html.EditorFor(x => x.FieldTypeID, new { style="width:20px;" })%> 

    Stream ID: 
    <%: Html.EditorFor(x => x.StreamID) %> 
</div> 

正常情况下应该采取产生正确的输入名称的照顾，但是为了避免人们以此为例，我再次重复使用适当的视图模型。