Select() 在 ThenInclude() 中不起作用

Question

我正在尝试检索具有screenings 列表的movie 对象。 screenings 中的每个对象都有一个 theater 对象，而该对象又具有一个 screenings 列表。我试图摆脱theater 中的screenings 列表，所以我创建了一个theaterDTO 模型。

what I'm trying to achieve

    var x = _context.Movies
                .Where(m => movieId == m.Id)
                .Include(m => m.Screenings)

这会导致screening 列表被多次检索：在movie 对象和movie.theaters 中的每个theater 对象中

这是Screening 类：

public class Screening : BaseEntity
    {
        public Theater Theater { get; set; }
        public Movie Movie { get; set; }
        public DateTime Time { get; set; }

        public ICollection<Booking> Bookings { get; set; }    
        public Screening()
        {
            Bookings = new List<Booking>();
        }
    }

Movie:

public class Movie : BaseEntity
    {
        public string Name { get; set; }
        public string Body { get; set; }
        public string Dir { get; set; }
        public string Pic { get; set; }

        public ICollection<Screening> Screenings { get; set; }
        public Movie()
        {
            Screenings = new List<Screening>();
        }
    }

Theater:

public class Theater : BaseEntity
    {
        public string Address { get; set; }
        public string Name { get; set; }

        public ICollection<Screening> Screenings { get; set; }
        public Theater()
        {
            Screenings = new List<Screening>();
        }
    }

TheaterDTO:

public class TheaterDTO 
    {
        public string Address { get; set; }
        public string Name { get; set; }
    }

功能：

[HttpGet]
    [Route("{movieId}")]
    public Movie GetMovieById(Guid movieId)
    {
        return _context.Screenings
            .Where(m => movieId == m.Id)
            .Select(x => new TheaterDTO
            {
                Name = x.Theater.Name,
                Address = x.Theater.Address
            }).FirstOrDefault();
    }

Answer 1

首先定义一个 MovieDTO：

public class MovieDTO
{
    public string Name { get; set; }
    public string Body { get; set; }
    public string Dir { get; set; }
    public string Pic { get; set; }
    public List<ScreeningDTO> Screenings { get; set; }
}

public class ScreeningDTO
{
    public TheaterDTO Theater { get; set; } 
}

public class TheaterDTO
{
    public string Address { get; set; }
    public string Name { get; set; }
}

这样的拍摄数据：

var x = _context.Movies
            .Where(m => movieId == m.Id)
            .Include(m => m.Screenings)
               .ThenInclude(s => s.Theater)
            .Where(p => p.Id == movieId)
            .Select(p => new MovieDTO {
                      Name = p.Name,
                      Body = p.Body,
                      Dir = p.Dir,
                      Pic = p.Pic,
                      Screening = p.Screenings.Select(x => new ScreeningDTO {
                                     Theater = new TheaterDTO {
                                        Name = x.Theater.Name,
                                        Address = x.Theater.Address
                                    }
                       }).ToList()
                    }).FirstOrDefault();