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c# - C# 深度连接查询

问题描述

目前我有下面的代码，它返回一个列表，它通过 4 个表锦标赛 -> Tournament_PlayerIDs -> PlayerIDs_Players -> Players。我想要做的是返回一个玩家使用他们的 ID 注册参加的锦标赛列表。

    public IEnumerable<Tournament> GetAllTournaments()
    {
        return _appDbContext.Tournaments
       .Include(f => f.PlayerIDIDs)
       .ThenInclude(PlayerIDIDs => PlayerIDIDs.Player)
       .ThenInclude(Player=> Player.Player)
       .Include(f => f.TournamentGame)
       .Include(f => f.TournamentFormat).ToList();
    }

我想要的是

public IEnumerable<Tournament> GetAllTournaments(string id)
    {
        return _appDbContext.Tournaments
       .Include(f => f.PlayerIDIDs)
       .ThenInclude(PlayerIDIDs => PlayerIDIDs.Player)
       .ThenInclude(Player=> Player.Player)
       .Include(f => f.TournamentGame)
       .Include(f => f.TournamentFormat)
       .Where (f.PlayerIDIDs.Player.Player.Id == id)
       .ToList();
    }

模型结构

public class Tournament
{
    [Key]
    public int TournamentID { get; set; }
    [Required]
    [StringLength(100, ErrorMessage = "Game name is required")]
    public string TournamentName { get; set; }
    [Required]
    [StringLength(5000, ErrorMessage = "Short Desc is required")]
    public string TournamentDescription { get; set; }
    public bool IsMajorTournament { get; set; }
    public decimal TournamentFee { get; set; }
    public DateTime TournamentStartTime { get; set; }

    //Foregin Keys
    public int? GameID { get; set; }
    public Game TournamentGame { get; set; }
    public int? FormatID { get; set; }
    public Format TournamentFormat { get; set; }
    public ICollection<PlayerID_Tournament> PlayerIDIDs { get; } = new List<PlayerID_Tournament>();

}

public class PlayerID_Tournament
{
    public int PlayerIDID { get; set; }
    public PlayerID Player { get; set; }
    public int TournamentID { get; set; }
    public Tournament Tournament { get; set; }
}

public class PlayerID
{
    //Identity for Player ID
    [Key]
    public int PlayerIDID { get; set; }
    //Id for Game such as DCI number
    public string PlayerGameID { get; set; }
    //game info
    public int GameId { get; set; }
    public Game Game { get; set; }
    //user info
    public string PlayerId { get; set; }
    public ApplicationUser Player { get; set; }
    public ICollection<PlayerID_Tournament> Tournaments { get; } = new List<PlayerID_Tournament>();
}

public class ApplicationUser : IdentityUser
{
    public string FirstName { get; set;}
    public string LastName { get; set; }
    public ICollection<PlayerID> PlayerIDs { get; set; }
}

标签： c#entity-framework-core

解决方案

我相信您正在寻找的东西称为SelectMany。我相信链接中的示例涵盖了您想要的内容（获取给定玩家参加的所有锦标赛）

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