包括关联表中的数据

我想问一下如何在我的案例中包含数据。我创建了一个关联表,定义了 BusinessGlosItems . 在下一步中,我创建了 商务词汇 并通过子关系和父关系包含引用表。

最后我需要显示 商务词汇 所有相关数据。听起来很简单,但我不知道如何解决这个问题。有人能帮忙吗?

我的域类如下:

public class BusinessGlosItem
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }
    public string BGIName { get; set; }

    [InverseProperty("ChildBGItem")]
    public ICollection<Reference> ChildReferences { get; set; }
    [InverseProperty("ParentBGItem")]
    public ICollection<Reference> ParentReferences { get; set; }
}

public class Reference
{
    public int Id { get; set; }
    [ForeignKey("ChildBGItem")]
    public int? ChildGlosItemId { get; set; }
    [ForeignKey("ParentBGItem")]
    public int? ParentGlosItemId { get; set; }

    public int ReferenceTypeId { get; set; }

    public virtual ReferenceType ReferenceType { get; set; }

    public virtual BusinessGlosItem ChildBGItem { get; set; }

    public virtual BusinessGlosItem ParentBGItem { get; set; }
}

我想做的是:

@page
@model BusinessGlosItem.DetailsModel

<div>
    <table class="table table-hover">
        <th>Reference Type</th>
        <th>Parent Item Name</th>
        <th>Child Item Name</th>

        @foreach (var item in Model.BusinessGlosItem.ParentReferences)
        {
            <tr>
                <td>@item.ReferenceType.ReferenceTypeName</td>
                <td>@item.ParentBGItem.BGIName</td>
                <td>@item.ChildGlosItemId</td> //Here I would like to see the ChildItem Name
            </tr>
        }
    </table>
</div>

我得到 NullReferenceException: Object reference not set to an instance of an object. on the line 从这个角度来看。

我的方法是:

public BusinessGlosItem BusinessGlosItem { get; set; }

public async Task<IActionResult> OnGetAsync(int? id)
{
      if (id == null)
      {
                return NotFound();
      }

      BusinessGlosItem = await _context.businessGlosItem                 
                .Include(x => x.BusinessArea)
                .Include(x => x.BusinessGlosItemStatus)
                .Include(x => x.ChildReferences).ThenInclude(x=>x.ReferenceType)
                .Include(x => x.ParentReferences).ThenInclude(x=>x.ReferenceType)
                .Include(x=>x.businessGlosItemComments)
                .SingleOrDefaultAsync(m => m.Id == id);

      if (BusinessGlosItem == null)
      {
           return NotFound();
      }
      return Page();
 }

提前多谢!