需要 C# 后端专业版！数据怪异

Question

这是我的代码

  public Tournament Read(int id)
    {
        using (var context = new DragonLairContext())
        {
            Tournament tournament = context.Tournaments
                 .Include(a => a.Game)
                    .Include(g => g.Game.Genre)
                    .Include(b => b.Groups.Select(g => g.Teams))
                    .Include(k => k.Groups.Select(y => y.Teams.Select(l => l.Players)))
                    .Include(c => c.TournamentType)
                    .FirstOrDefault(d => d.Id == id);
            return tournament;               
        }
    }

我正在使用 API，由于序列化问题，我需要将我的实体转换为 DTOobject。

这是来自 Dto 转换器的 sn-p

 public override DTOTournament Convert(Tournament t)
    {
        if (t.Game == null || t.TournamentType == null || t.Groups == null) throw new ArgumentException("Missing some data");
        DTOTournament dtoTournament = new DTOTournament();
        List<DTOGroup> dtoGroups = new List<DTOGroup>();

        DTOTournamentType dtoTournamentType = new DTOTournamentType() { Id = t.TournamentType.Id, Type = t.TournamentType.Type };


        foreach (var group in t.Groups)
        {
            if (group.Teams == null) return dtoTournament;
            List<DTOTeam> dtoTeams = new List<DTOTeam>();
            foreach (var team in group.Teams)
            {
                List<DTOPlayer> dtoPlayers = new List<DTOPlayer>();
                if (team.Players == null) return dtoTournament;
                foreach (var player in team.Players)
                {
                    dtoPlayers.Add(new DTOPlayer() { Id = player.Id, Name = player.Name });
                }
                dtoTeams.Add(new DTOTeam()
                {
                    Id = team.Id,
                    Name = team.Name,
                    Win = team.Win,
                    Loss = team.Loss,
                    Draw = team.Draw,
                    DtoPlayers = dtoPlayers
                });
            }
            dtoGroups.Add(new DTOGroup()
            {
                Id = group.Id,
                Name = group.Name,
                DtoTeams = dtoTeams,
                DtoTournament = dtoTournament
            });
        }

        dtoTournament.DTOTournamentType = dtoTournamentType;
        dtoTournament.Id = t.Id;
        dtoTournament.Name = t.Name;
        dtoTournament.StartDate = t.StartDate;
        dtoTournament.DtoGroups = dtoGroups;
        dtoTournament.DtoGame = new DTOGame() { Id = t.Game.Id, Name = t.Game.Name, DtoGenre = new DTOGenre() { Id = t.Game.Genre.Id, Name = t.Game.Genre.Name } };
        return dtoTournament;
    }

这是 Json

     {
  "$id": "1",
  "Id": 1,
  "Name": "I'm a Tournament",
  "StartDate": "2015-12-08T00:00:00",
  "DTOTournamentType": {
    "$id": "2",
    "Id": 1,
    "Type": "I'm type 2vs2",
    "DtoTournaments": null
  },
  "DtoGroups": [
    {
      "$id": "3",
      "Id": 1,
      "Name": "I'm a Group",
      "DtoTournament": {
        "$ref": "1"
      },
      "DtoTeams": [
        {
          "$id": "4",
          "Id": 1,
          "Draw": 0,
          "Loss": 0,
          "Win": 0,
          "Name": "I'm a Team",
          "DtoPlayers": [
            {
              "$id": "5",
              "Id": 1,
              "Name": "I'm a Group",
              "DtoTeams": null
            }
          ],
          "DtoGroups": null
        },
        {
          "$id": "6",
          "Id": 2,
          "Draw": 0,
          "Loss": 0,
          "Win": 0,
          "Name": "I'm a Team",
          "DtoPlayers": [
            {
              "$id": "7",
              "Id": 1,
              "Name": "I'm a Group",
              "DtoTeams": null
            }
          ],
          "DtoGroups": null
        }
      ]
    }
  ],
  "DtoGame": {
    "$id": "8",
    "Id": 1,
    "Name": "Im a Game - Wars",
    "DtoGenre": {
      "$id": "9",
      "Id": 1,
      "Name": "I'm Genre Roleplaying",
      "DtoGames": null
    },
    "DtoTournaments": null
  }
}

我的数据库包含 3 个玩家 - 笔记转换为 json

      [
  {
    "$id": "1",
    "Id": 1,
    "Name": "I'm player Søren",
    "DtoTeams": [
      {
        "$id": "2",
        "Id": 1,
        "Draw": 0,
        "Loss": 0,
        "Win": 0,
        "Name": "I'm a Team",
        "DtoPlayers": null,
        "DtoGroups": null
      }
    ]
  },
  {
    "$id": "3",
    "Id": 2,
    "Name": "I'm player Mark",
    "DtoTeams": [
      {
        "$id": "4",
        "Id": 1,
        "Draw": 0,
        "Loss": 0,
        "Win": 0,
        "Name": "I'm a Team",
        "DtoPlayers": null,
        "DtoGroups": null
      }
    ]
  },
  {
    "$id": "5",
    "Id": 3,
    "Name": "I'm player René",
    "DtoTeams": [
      {
        "$id": "6",
        "Id": 2,
        "Draw": 0,
        "Loss": 0,
        "Win": 0,
        "Name": "I'm a Team",
        "DtoPlayers": null,
        "DtoGroups": null
      }
    ]
  }
]

所以我真的无法弄清楚我的问题。为什么我的 DtoPlayer.Name 与 DtoGroup.Name 同名。看看我的包含。

Answer 1

抛出此异常的原因是您尝试使用 在您已释放数据库上下文后未从数据库中检索到的属性。您可以在调试时看到数据，因为变量是在 using 范围内定义的。您还应该在 Group 类上获取 Teams。

using (var context = new DragonLairContext())
{
    Tournament tournament = context.Tournaments 
            .Include(a => a.Game)
            .Include(g => g.Game.Genre)
            .Include(b => b.Groups.Select(g => g.Teams))
            .Include(c => c.TournamentType)
            .FirstOrDefault(d => d.Id == id);

    return tournament;               
}

Answer 2

既然你说你可以在调试模式下看到数据，试试这个方法。

  Tournament tournament = context.Tournaments
            .Include(a => a.Game)
            .Include(g => g.Game.Genre)
            .Include(b => b.Groups)
            .Include(c => c.TournamentType).ToList()
            .FirstOrDefault(d => d.Id == id);