使用过滤器 Linq EF5 将实体包含到子集合中

Question

我在过滤子集合时遇到问题，过滤已完成，但我需要在集合中包含额外的实体，我不知道该怎么做

我有一个实体 Employee

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

    public string EmpNum { get; set; }

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

和集合实体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; }
}

我用投影来过滤

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)
            });

这是结果模型

public class EmployeeLeatestProfileModel {


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

}

问题是当我尝试获取国籍时，我没有找到它的数据，这似乎不包含在查询中！！

那么我可以做些什么来为子集合 EmoployeeProfile 包含国籍实体或任何其他实体

顺便说一句，我没有使用延迟加载

Answer 1

您可以使用对象查询来代替投影，包括传入一个字符串。

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

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

尚未对此进行测试，但请尝试选择匿名集合。

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();