Question

context.Projects
.Include(x => x.Members) //List<Member> public class Member
.Include(x => x.Members.Select(z => z.City)) //public class City
.ToList();

从项目

中选择

包含 project.Members

的列表

包括 project.Members.City

中的每一个

需要向结果中添加一些数据

context.Projects
.Include(x => x.Members) 
.Include(x => x.Members.Select(z => z.City)) 
.Select(x => new {
    Project = x,
    Amount = 22
})
.ToList();

已填充

项目属性，但成员为空

问题1 - 如何将 Project.Members 包含在 new {Project = x}

中

我接下来

context.Projects
.Include(x => x.Members) //List<Member>
.Include(x => x.Members.Select(z => z.City)) //City is navigation property
.Select(x => new {
    Project = x,
    Members = x.Members,
    Amount = 22
})
.ToList();

项目属性已填充且成员已填写但成员[0] .City为空

问题2 - 如何填写会员[0]。城市

P.S。

EntityFramework 6

public class Project
{
    public Guid Id { get; set; }
    public string Name { get; set; }
    public List<ProjectMember> Members { get; set; }
}

public class ProjectMember
{
    public Guid ProjectId { get; set; }
    public Project Project { get; set; }

    public Guid CityId { get; set; }
    public City City { get; set; }
}

P.S.S

这项工作 - 但代码开销

context.Projects
.Include(x => x.Members) //List<Member>
.Include(x => x.Members.Select(z => z.City)) //City is navigation property
.Select(x => new {
    Project = x,
    Members = x.Members.Select(z => new {
        Item = z,
        City= z.City
    }).ToList(),
    Amount = 22
})
.ToList();

Answer 1

在include之后执行的任何操作（过滤除外）都将导致包含被丢弃。通过在包含之后调用AsEnumerable，您将确保执行查询，其余操作将在内存中完成：

context.Projects 
       .Include(x => x.Members) 
       .Include(x => x.Members.Select(z => z.City))
       .AsEnumerable() 
       .Select(x => new { Project = x, Amount = 22 }) 
       .ToList();

Answer 2

将您的导航属性声明为虚拟，列为ICollection，并在为实体保湿时让EF替换为其具体实现：

.ogg

Linq EF Include（）包含Select（）新类型丢失

2 个答案: