在数据传输中包含相关实体 Object

Question

我正在尝试提取会议列表及其相关预订。据我了解，我应该将我的数据放入 DTO。我可以通过此获得会议列表...

        var meetings = from m in db.meetings.Take(2)
                    select new MeetingDTO()
                    {
                        meetingid = m.meetingid,
                        meetingname = m.meeting_name,
                        businessname = m.business.name
                    };

        return meetings;

我尝试了几种不同的方法来包含相关的预订数据，但无法弄清楚语法。

我知道这有点离谱，但这就是我要实现的目标...

        var meetings = from m in db.meetings.Take(2)
                    select new MeetingDTO()
                    {
                        meetingid = m.meetingid,
                        meetingname = m.meeting_name,
                        businessname = m.business.name,
                        bookingsDTOs = from b in db.bookings
                                        select new bookingsDTO()
                                        {
                                            bookingid = b.bookingid,
                                            bookingname = b.name
                                        };
                    };

        return meetings;

这是我的 DTO 结构...

namespace testapi.Models
{
    public class MeetingDTO
    {
        public int meetingid { get; set; }
        public string meetingname { get; set; }
        public string businessname { get; set; }
        public virtual ICollection<bookingsDTO> bookingsDTOs { get; set; }
    }

    public class bookingsDTO
    {
        public int bookingid { get; set; }
        public string bookingname { get; set; }
    }
}

Answer 1

您可以使用 Include 扩展方法显式加载您的相关实体作为查询的一部分：

var meetings = from m in db.meetings.Include(m=>m.bookings).Take(2)
                select new MeetingDTO()
                {
                    meetingid = m.meetingid,
                    meetingname = m.meeting_name,
                    businessname = m.business.name
                    bookingsDTOs = m.bookings.Select(b=>new bookingsDTO()
                                                       {
                                                         bookingid = b.bookingid,
                                                         bookingname = b.name
                                                       })
                };
return meetings;

为了让您的生活更轻松，我建议您看看 Automapper。配置映射后，您可以执行类似的操作：

var meetings = from m in db.meetings.Include(m=>m.bookings).Take(2).ProjectTo<MeetingDTO>();

这tutorial是一个好的开始。

在数据传输中包含相关实体 Object

Including related entities in a Data Transfer Object

c#

asp.net-mvc

entity-framework

asp.net-web-api

dto