使用過濾器Linq EF5將子實體包含到子集合中

Question

我在過濾子集合時遇到問題，過濾已完成，但是我需要在集合中包括其他實體，我不知道該怎么做

我有實體員工

public class Employee
{
    [Key]
    public int EmployeeId { get; set; }

    public string EmpNum { get; set; }

    public virtual ICollection<EmployeeProfile> EmployeeProfiles { get; set; }
}

和集合實體EmployeeProfile

public class EmployeeProfile
{
    [Key]
    public int EmployeeProfileId { get; set; }


    [ForeignKey("Employee")]
    public int EmployeeId { get; set; }

    public string EmployeeName { get; set; }


    [ForeignKey("Nationality")]
    public int? NationalityId{ get; set; }

    ....

    public DateTime? UpdateDatetime { get; set; }

    public virtual Nationality Nationality{ get; set; }
    public virtual Employee Employee { get; set; }
}

我用投影來過濾

var employees = context.Employees
            .Include(e => e.EmployeeProfiles)
            .Include(e => e.EmployeeProfiles.Select(a => a.Nationality))
            .Select(e => new EmployeeLeatestProfileModel
            {
                EmployeeId = e.EmployeeId
                ,
                EmpNum = e.EmpNum
                ,
                LastUpdatedProfile = e.EmployeeProfiles
                        .Where(p => p.EmployeeId == e.EmployeeId)
                        .OrderByDescending(a => a.UpdateDatetime).Take(1)
            });

這就是結果模型

public class EmployeeLeatestProfileModel {


    public int EmployeeId { get; set; }
    public string EmpNum { get; set; }
    public IEnumerable<EmployeeProfile> LastUpdatedProfile;

}

事情是當我嘗試獲取國籍時，我沒有找到它的數據，這似乎不包含在查詢中！！

所以我該怎么做才能為孩子集合EmoployeeProfile包括國籍實體或其他任何實體

而且我沒有使用延遲加載

Answer 1

代替使用投影，您可以使用對象查詢包括傳遞一個字符串。

https://msdn.microsoft.com/en-us/library/bb738708(v=vs.110).aspx

.Include(e => e.EmployeeProfiles)
.Include("EmployeeProfiles.Nationality")
.Include("EmployeeProfiles.Employee")

尚未對此進行測試，但請嘗試選擇一個匿名集合。

var employees = context.Employees
    .Select(e => new
    {
        Employee = e,
        EmployeeProfiles = e.EmployeeProfiles,
        Nationalities = e.EmployeeProfiles.Select(a => a.Nationality)
    })
    .ToList() // do this to force the projection
    .Select(e => new EmployeeLeatestProfileModel
    {
        EmployeeId = e.Employee.EmployeeId,
        EmpNum = e.Employee.EmpNum,
        LastUpdatedProfile = e.EmployeeProfiles
            .Where(p => p.EmployeeId == e.Employee.EmployeeId)
            .OrderByDescending(a => a.UpdateDatetime)
            .Take(1)
    })
    .ToList();