在数据传输对象中包含相关实体

Question

I'm attempting to pull a list of meetings with their related bookings. As I understand it, I should put my data into a DTO. I'm able to get a list of meetings with this...

        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;

I've tried several different methods of including the related booking data, but can't figure the syntax out.

I know this is way off, but this is the idea of what I'm going for...

        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;

This is my DTO structure...

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

You can use Include extension method to explicitly load your related entity as part of your query:

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;

To make easier your life I suggest you take a look to Automapper . You can do something like this once you configure your mappings:

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

This tutorial is a good start.