c# - 从另一个数据库中的另一个模型引用一个模型asp.net mvc

Question

我的 Controller 中有以下方法:

    public ActionResult OwnerList()
    {                              
        var owners = (from s in db.Owners                       
                     orderby s.Post.PostName
                     select s).ToList();

        var viewModel = owners.Select(t => new OwnerListViewModel
        {
             Created = t.Created,
             PostName = t.Post.PostName,
             Dormant = t.Dormant,
             OwnerId = t.OwnerId,
        });
        return PartialView("_OwnerList", viewModel);
    }

运行它时，我从 owners 变量中得到以下错误:

{"Invalid object name 'dbo.Post'."}

我的模型是这些

在所有者数据库中

        public class Owner
{
    public int OwnerId { get; set; }

    [Column(TypeName = "int")]
    public int PostId { get; set; }

    [Column(TypeName = "bit")]
    public bool Dormant { get; set; }

    [Column(TypeName = "datetime2")]
    public DateTime Created { get; set; }

    public virtual ICollection<Asset> Assets { get; set; }

    public virtual Post Post { get; set; }
}

在人物数据库中

public class Post
{
    public int PostId { get; set; }

    [StringLength(50)]
    [Column(TypeName = "nvarchar")]
    public string PostName { get; set; }

    [Column(TypeName = "bit")]
    public bool Dormant { get; set; }

    [StringLength(350)]
    [Column(TypeName = "nvarchar")]
    public string Description { get; set; }

    public virtual ICollection<Contract> Contracts { get; set; }

    public virtual ICollection<Owner> Owners { get; set; }
}

观点是:

@model IEnumerable<IAR.ViewModels.OwnerListViewModel>



<table class="table">

@foreach (var group in Model
            .OrderBy(x => x.Dormant)
            .GroupBy(x => x.Dormant))
{
    <tr class="group-header">
        @if (group.Key == true)
        {
            <th colspan="12"><h3>Dormant:- @group.Count()</h3></th>
        }
        else
        {
            <th colspan="12"><h3>Active:- @group.Count()</h3></th>
        }

    </tr>
    <tr>
        <th>
            @Html.DisplayNameFor(model => model.PostName)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Created)
        </th>
        <th></th>
    </tr>

    foreach (var item in group
                )
    {
        <tr>
            <td>
                @Html.DisplayFor(modelItem => item.PostName) @Html.HiddenFor(modelItem => item.OwnerId)
            </td>
            <td>
                @Html.DisplayFor(modelItem => item.Created)
            </td>
            <td>
                @if (group.Key == true)
                {
                    @Html.ActionLink("Make Active", "Dormant", new { ownerId = item.OwnerId })
                }
                else
                {
                    @Html.ActionLink("Make Dormant", "Dormant", new { ownerId = item.OwnerId })
                }
            </td>
        </tr>
    }
}

</table>

我确信这很简单，但我做错了什么以允许它引用所有者的帖子？

Answer 1

给定 s.Post 为 null，您已禁用 Entity Framework 的延迟加载。要么启用延迟加载，要么显式加载导航属性:

from s in db.Owners.Include(o => o.Post)
orderby s.Post.PostName
...

至于您的编辑，鉴于 Owner.Post 在不同的数据库中，这是一个完全不同的问题。在网上搜索，例如 Cross database querying in EF和 Joining tables from two databases using entity framework一些提示。在数据库级别链接它们(使用链接服务器或同义词和 View )，或在您的代码中修复它们(循环遍历 Owners 并查找他们的 Post) .