嵌套在模型中的集合不受MVC 3约束（始终为空） [英] Collection Nested within Model is Not Bound by MVC 3 (Always null)

问题描述

我有一个模型，代表ASP.NET MVC 3和实体框架5.0中大学的各种信息。该模型具有另一个模型的ICollection，称为TrendModel。无论我做什么，这个集合似乎永远不会被MVC存储/绑定。

当我在运行时手动将该集合设置为某个东西（在从数据库中检索到该集合之后），该集合当然不再是空的，但是无论我看起来如何设置它然后存储在数据库中，当我从数据库中检索时，趋势总是为空。

UniversityModel：

  public class UniversityModel 
 {
 [Key] 
 public string univ_id {get;组; } 
 
 public string ipeds_id {get;组; } 
 public string name {get;组; } 
 public bool relig {get;组; } 
 
 #region位置信息
 
 public string city {get;组; } 
 public string state {get;组; } 
 public string urbanization {get;组; } 
 public double latitude {get;组; } 
 public double longitude {get;组; } 
 
 #endregion 
 
 public ICollection< TrendModel>趋势{get;组; } 
} 
  

TrendModel：

  public class TrendModel 
 {
 [Key] 
 public string id {get;组; } 
 public ushort year {get;组; } 
 public uint？能力{get;组; } 
 public uint？率{get;组; } 
 public uint？吃饭{get;组; } 
 public bool？ forProfit {get;组; } 
 public bool？控制{get;组; } 
 public string degree {get;组; } 
 public bool？土地出让人组; } 
 public bool？运动{get;组; } 
 public string calendar {get;组; } 
 public bool？必须{get;组; } 
} 
  

不知道是否相关，但是如果我把一个构造函数UniversityModel将趋势设置为空列表，然后趋势不再为空，并且是空列表。

这是一个模型绑定问题，还是后期问题？对不起，如果我完全离基，我是MVC和ASP.NET的新手。

解决方案

这个问题是由我强制执行对趋势的懒惰加载来解决的，所以该属性现在显示为：

  public virtual ICollection< TrendModel>趋势{get;组; } 
  

I have a model that represents various information about a university in ASP.NET MVC 3 and Entity Framework 5.0. The model has an ICollection of another model, called TrendModel. This collection seems to never be stored/bound by MVC at any point, no matter what I do.

When I manually set this collection to something at run time (after it is retrieved from the database), the collection is of course no longer null, but whatever I seem to set it to and then store in the database, trends is always null when I retrieve it from the database.

UniversityModel:

public class UniversityModel
{
    [Key]
    public string univ_id { get; set; }

    public string ipeds_id { get; set; }
    public string name { get; set; }
    public bool religious { get; set; }

    #region Location Information

    public string city { get; set; }
    public string state { get; set; }
    public string urbanization { get; set; }
    public double latitude { get; set; }
    public double longitude { get; set; }

    #endregion

    public ICollection<TrendModel> trends { get; set; }
}

TrendModel:

public class TrendModel
{
    [Key]
    public string id { get; set; }
    public ushort year { get; set; }
    public uint? capacity { get; set; }
    public uint? rate { get; set; }
    public uint? meals { get; set; }
    public bool? forProfit { get; set; }
    public bool? control { get; set; }
    public string degree { get; set; }
    public bool? landgrant { get; set; }
    public bool? athletic { get; set; }
    public string calendar { get; set; }
    public bool? required { get; set; }
}

Not sure if it is relevant, but if I put in a constructor for UniversityModel that sets trends to an empty list, then trends is no longer null and is an empty list.

Is this a model binding issue, or a post issue or something? Sorry if I'm completely off-base, I'm pretty new to MVC and ASP.NET.

解决方案

As it turn out, the issue was fixed simply by me enforcing lazy loading on the trends, so the property now reads:

public virtual ICollection<TrendModel> trends { get; set; }

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