我遇到了这个EF 2.1查询的问题:
return await _context.CorrespondenceItems
.Include(x => x.Statuses.OrderByDescending(y => y.Date))
.OrderByDescending(x => x.DateCreated)
.ToListAsync();
问题是Statuses集合的OrderByDescending。我得到的错误是:
System.InvalidOperationException: The Include property lambda expression 'x => {from CorrespondenceItemStatus y in x.Statuses orderby [y].Date desc select [y]}' is invalid. The expression should represent a property access: 't => t.MyProperty'. To target navigations declared on derived types, specify an explicitly typed lambda parameter of the target type, E.g. '(Derived d) => d.MyProperty'
这是我的(简化)模型:
public class CorrespondenceItem
{
[Key]
public int CorrespondenceItemId { get; set; }
public virtual List<CorrespondenceItemStatus> Statuses { get; set;
}
public class CorrespondenceItemStatus
{
[Key]
public int CorrespondenceItemStatusId { get; set; }
public int CorrespondenceItem_CorrespondenceItemId { get; set; }
[ForeignKey("CorrespondenceItem_CorrespondenceItemId")]
public virtual CorrespondenceItem CorrespondenceItem { get; set; }
public DateTime Date { get; set; }
}
更新:要明确的是,我希望按日期顺序递减对应项目的集合,其状态按日期降序排列
请尝试以下代码:
var result = await _db.CorrespondenceItem
.Include(i => i.Statuses)
.Select(r => new CorrespondenceItem
{
CorrespondenceItemId = r.CorrespondenceItemId,
DateCreated = r.DateCreated,
Statuses = r.Statuses.OrderByDescending(s => s.Date).ToList()
})
.OrderByDescending(i => i.DateCreated)
.ToListAsync();