ICollection中的对象不能通过模型​​传递来查看 [英] Objects in ICollection not passed with model to view

问题描述

我正在尝试创建一个可以发表评论的消息的网站。我一直在从pluralsight.com跟随指导，我已经遵循了这封信的指导，但是当我调试并在运行时看看模型里面的内容时，不会包含评论。

我的DB类：

  public class ProjectDB {
 public DbSet< ContentNode> ContentNodes {get;组; } 
 public DbSet< Comment>评论{get;组; 
 
 protected override void OnModelCreating（DbModelBuilder modelBuilder）
 {
 
 base.OnModelCreating（modelBuilder）; 
 
 modelBuilder.Entity< ContentNode>（）
 .Property（n => n.ID）.HasColumnName（NodeID）; 
 modelBuilder.Entity< ContentNode>（）
 .HasMany（node => node.Comments）
 .WithRequired（comment => comment.Node）; 
} 
} 
  

涉及的模型：

  public class ContentNode：Node 
 {
 public ContentType ContentType {get;组; } 
 public ContentCategory类别{get;组; } 
 public ICollection< Comment>评论{get;组; } 
 
 public ContentNode（）
 {
注释=新列表<注释>（）; 
} 
} 
 
 public class注释
 {
 public int ID {get;组; } 
 public ContentNode Node {get;组; } 
 public string Body {get;组; } 
} 
  

控制器方法从db中提取新闻文章并将其发送到视图

  [GET（frettir / {year} / {month} / {day} / {title}）] 
 public ActionResult GetArticle（int year，int month，int day，string title）
 {
 var model =（from f in _db.ContentNodes 
 where f.dateCreated.Year = = year&&b $ b f.dateCreated.Month == month&& 
 f.dateCreated.Day == day&& 
 f.Title == title& & 
 f.ContentType.ID == 1 
 select f）.Single（）; 
 
 return View（model）; 
} 
  

最后视图本身：

  @model Project.Models.ContentNode 
 
 @ {
 ViewBag.Title =GetByID; 
} 
 
< h2> GetByID< / h2> 
 
< fieldset> 
< legend>新闻< / legend> 
 
< div class =display-label> 
 @ Html.DisplayNameFor（model => model.Title）
< / div> 
< div class =display-field> 
 @ Html.DisplayFor（model => model.Title）
< / div> 
 
< div class =display-label> 
 @ Html.DisplayNameFor（model => model.Body）
< / div> 
< div class =display-field> 
 @ Html.DisplayFor（model => model.Body）
< / div> 
 
< div class =display-label> 
 @ Html.DisplayNameFor（model => model.dateCreated）
< / div> 
< div class =display-field> 
 @ Html.DisplayFor（model => model.dateCreated）
< / div> 
< / fieldset> 
< p> 
 @ Html.ActionLink（编辑，编辑，新的{id = Model.ID}）| 
 @ Html.ActionLink（返回列表，索引）
< / p> 
 
 @foreach（Model.Comments中的var项）
 {
 @ Html.Partial（_评论，项目）
} 
 
 @ Html.ActionLink（新评论，创建，评论，新的{NodeID = Model.ID}，null）
  

我已经看了一些例子，我看了几十次视频指南，看看我做错了什么。我想出的唯一的解决方案是加入NodeContent表与注释表，并将其投射到另一个模型，但从我可以收集不应该需要。

解决方案

  var model = _db.ContentNodes 
 .Include（f => f.Comments）// eager加载子集
 .Single（f => f.dateCreated.Year == year 
&& f.dateCreated .Month == month 
&& f.dateCreated.Day == day 
&& f.Title == title 
&& f.ContentType.Id == 1）; 
  

I'm trying to create a site with news that can have comments. I've been following guides from pluralsight.com and I've followed what is done in the guide to the letter but when i debug and look at what's inside the model at runtime the comments aren't included.

My DB class:

public class ProjectDB {
        public DbSet<ContentNode> ContentNodes{ get; set; }
        public DbSet<Comment> Comments { get; set; }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {

            base.OnModelCreating(modelBuilder);

            modelBuilder.Entity<ContentNode>()
                .Property(n => n.ID).HasColumnName("NodeID");
            modelBuilder.Entity<ContentNode>()
                .HasMany(node => node.Comments)
                .WithRequired(comment => comment.Node);
        }
}

The models involved:

    public class ContentNode : Node
    {
        public ContentType ContentType { get; set; }
        public ContentCategory Category { get; set; }
        public ICollection<Comment> Comments { get; set; }

        public ContentNode()
        {
            Comments = new List<Comment>();
        }
    }

    public class Comment
    {
        public int ID { get; set; }
        public ContentNode Node { get; set; }
        public string Body { get; set; }
    }

The controller method that pulls the news article from the db and sends it to the view

[GET("frettir/{year}/{month}/{day}/{title}")]
public ActionResult GetArticle( int year, int month, int day, string title)
{
    var model = (from f in _db.ContentNodes
                 where f.dateCreated.Year == year &&
                       f.dateCreated.Month == month &&
                       f.dateCreated.Day == day &&
                       f.Title == title &&
                       f.ContentType.ID == 1
                 select f).Single();

    return View(model);
}

And finally the view itself:

@model Project.Models.ContentNode

@{
    ViewBag.Title = "GetByID";
}

<h2>GetByID</h2>

<fieldset>
    <legend>News</legend>

    <div class="display-label">
         @Html.DisplayNameFor(model => model.Title)
    </div>
    <div class="display-field">
        @Html.DisplayFor(model => model.Title)
    </div>

    <div class="display-label">
         @Html.DisplayNameFor(model => model.Body)
    </div>
    <div class="display-field">
        @Html.DisplayFor(model => model.Body)
    </div>

    <div class="display-label">
         @Html.DisplayNameFor(model => model.dateCreated)
    </div>
    <div class="display-field">
        @Html.DisplayFor(model => model.dateCreated)
    </div>
</fieldset>
<p>
    @Html.ActionLink("Edit", "Edit", new { id=Model.ID }) |
    @Html.ActionLink("Back to List", "Index")
</p>

    @foreach (var item in Model.Comments)
    {
        @Html.Partial("_Comment",item)
    }

@Html.ActionLink("New comment", "Create", "Comment", new { NodeID = Model.ID }, null)

I've looked at examples and I've looked over the video guide a dozen times to see what i did wrong. The only solution that I've come up with is joining the NodeContent table with the Comments table and projecting it into another model but from what i can gather that shouldn't be required.

Any help is appreciated.

解决方案

var model = _db.ContentNodes
    .Include(f => f.Comments) // eager load the child collection
    .Single(f => f.dateCreated.Year == year 
         && f.dateCreated.Month == month
         && f.dateCreated.Day == day 
         && f.Title == title 
         && f.ContentType.Id == 1);

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