一个表有两个指向另一个表的链接。 .Include 如何指定这些链接之一？

Question

tblWorkOrder 通过 tblWorkOrder.EnteredBy 和 tblWorkorder.ClosedBy 有两个到 tblUser 的链接。下面的代码选择 ClosedBy 链接。如何指定 OpenedBy 链接？

public IEnumerable<SelectListItem> GetEnteredBy()
{
    using (var context = new FacilityEntities())
    {
        List<SelectListItem> user = context.tblWorkOrder.AsNoTracking().Include("tblUser")
            .GroupBy(x => new { x.tblUser.LastName, x.tblUser.FirstName, x.tblUser.UserID })
            .Select(x =>
            new SelectListItem
            {
                Value = x.Key.UserID,
                Text = string.Concat(x.Key.FirstName, " ", x.Key.LastName)
            }).ToList();
        var usertip = new SelectListItem()
        {
            Value = null,
            Text = "Select"
        };
        user.Insert(0, usertip);
        return new SelectList(user, "Value", "Text");
    }
}

Answer 1

您需要在 Entity 中定义关系，使用ForeignKey 属性明确定义哪个外键关联到哪个导航属性。

public class tblWorkOrder 
{
    public long? CloseById { get; set; } // ForeignKey
    [Foreignkey("CloseById")]  // CloseBy navigation property is associated to CloseById
    public tblUser CloseBy{ get; set; } // assuming tblUser is the name of your entity

    public long? EnteredById { get; set; }
    [ForeignKey("EnteredById")]
    public tblUser EnteredBy { get; set; }

    ...
}

正确定义导航属性后，您可以简单地将它们包含在查询中：

context.tblWorkOrder.AsNoTracking().Include(r => r.CloseBy).Include(r => r.EnteredBy)
...