孩子们不会更新Xamarin SQLite扩展-ManyToMany关系

如何解决孩子们不会更新Xamarin SQLite扩展-ManyToMany关系

我有四个具有属性的表（成员具有玩家，每个成员都参与许多体育运动）最后一个表用于多对多关系的中间表

[Table("Members")]
public class MemberModel : BaseDatabaseItem
{
    public string MemberShipCode { get; set; }
    public string MemberShipYear { get; set; }

    [OneToMany(CascadeOperations = CascadeOperation.All)]
    public List<PlayerModel> MembershipNPlayers { get; set; }
}

[Table("Players")]
public class PlayerModel : BaseDatabaseItem
{
    public string PlayerName { get; set; }

    public double PlayerPayment { get; set; }

    [ForeignKey(typeof(MemberModel))]
    public int MemberModelId { get; set; }

    [ManyToMany(typeof(PlayerSport))]
    public List<Sport> Sports { get; set; }
}

[Table("Sports")]
public class Sport : BaseDatabaseItem
{
    private SportCaegory sportCaegory;

    public string SportName { get; set; }

    [Ignore]
    public SportCaegory SportCaegory 
    {
        get 
        {
            return sportCaegory = new SportCaegory
            {
                SportPrice = SportPrice,SportType = SportType
            };
        }
        set
        {
            sportCaegory = value;
            if (sportCaegory == null)
                return;
            SportType = sportCaegory.SportType;
            SportPrice = sportCaegory.SportPrice;
        }
    }

    public string SportType { get; set; }
    public double SportPrice { get; set; }

    [ManyToMany(typeof(PlayerSport))]
    public List<PlayerModel> Players { get; set; }

}

public class PlayerSport : BaseDatabaseItem
{
    [ForeignKey(typeof(PlayerModel))]
    public int PlayerModelId { get; set; }

    [ForeignKey(typeof(Sport))]
    public int SportId { get; set; }
}

BaseDataItem只是具有ID（主要-AutoIn）的类

将会员保存在数据库中时，我先保存Sports然后再保存Players，最后保存该会员

            foreach (var sport in Players.SelectMany(p => p.Sports))
            {
                await _sportsRepository.SaveItemAsync(new Sport
                {
                    Id = sport.Id == 0 ? 0 : sport.Id,SportName = sport.SportName,SportCaegory = sport.SportCaegory
                });
            };

            foreach (var player in Players)
            {
                await _playersRepository.SaveItemAsync(new PlayerModel
                {
                    Id = player.Id == 0 ? 0 : player.Id,PlayerName = player.PlayerName,PlayerPayment = player.PlayerPayment,Sports = player.Sports
                });
                await _playersRepository.SaveWithChildrenAsync(player);

            };

            var member = new MemberModel
            {
                Id = string.IsNullOrEmpty(Id) ? 0 : int.Parse(Id),MemberShipCode = MemberShipCode,MemberShipYear = MemberShipYear,MembershipNPlayers = Players.ToList()
            };

            await _membersRepository.SaveWithChildrenAsync(member);

SaveWithChildrenAsync（仅检查ID）=>

    public async Task SaveWithChildrenAsync(T entity)
    {
        if (entity.Id != 0)
            await UpdateWithChildren(entity);
        else
            await InsertWithChildren(entity);
    }

当我检索数据时，每个运动员的体育项目列表计数始终等于零

        var member = await _membersRepository.GetWithChildren(MemberId) ;


        var MemberPlayers = member.MembershipNPlayers;

        foreach (var player in MemberPlayers)
        {
            var p = await _playersRepository.GetWithChildren(player.Id);
            Players.Add(p);
        }
        MemberShipCode = member.MemberShipCode;
        MemberShipYear = member.MemberShipYear;

如何解决？

解决方法

由于您未提供代码的某些部分，因此我编写了一个简单的代码来更新数据库并接收数据。您可以检查下面的代码。

模型类：

 [Table("Members")]
public class MemberModel : BaseDatabaseItem
{
    public string MemberShipCode { get; set; }
    public string MemberShipYear { get; set; }

    [OneToMany(CascadeOperations = CascadeOperation.All)]
    public List<PlayerModel> MembershipNPlayers { get; set; }
}

public class BaseDatabaseItem
{
    [PrimaryKey,AutoIncrement]
    public int Id { get; set; }
}

[Table("Players")]
public class PlayerModel : BaseDatabaseItem
{
    public string PlayerName { get; set; }

    public double PlayerPayment { get; set; }

    [ForeignKey(typeof(MemberModel))]
    public int MemberModelId { get; set; }

    [ManyToMany(typeof(PlayerSport))]
    public List<Sport> Sports { get; set; }
}

[Table("Sports")]
public class Sport : BaseDatabaseItem
{
    private SportCaegory sportCaegory;

    public string SportName { get; set; }

    [Ignore]
    public SportCaegory SportCaegory
    {
        get
        {
            return sportCaegory = new SportCaegory
            {
                SportPrice = SportPrice,SportType = SportType
            };
        }
        set
        {
            sportCaegory = value;
            if (sportCaegory == null)
                return;
            SportType = sportCaegory.SportType;
            SportPrice = sportCaegory.SportPrice;
        }
    }

    public string SportType { get; set; }
    public double SportPrice { get; set; }

    [ManyToMany(typeof(PlayerSport))]
    public List<PlayerModel> Players { get; set; }

}
public class SportCaegory
{
    public string SportType { get; set; }
    public double SportPrice { get; set; }


}
public class PlayerSport : BaseDatabaseItem
{
    [ForeignKey(typeof(PlayerModel))]
    public int PlayerModelId { get; set; }

    [ForeignKey(typeof(Sport))]
    public int SportId { get; set; }
}

插入和读取数据：

   var dbName = "CustomersDb.db3";
        var path = Path.Combine(System.Environment.
          GetFolderPath(System.Environment.
          SpecialFolder.Personal),dbName);


        var db = new SQLiteConnection(path);
        db.CreateTable<MemberModel>();
        db.CreateTable<PlayerModel>();
        db.CreateTable<PlayerSport>();
        db.CreateTable<Sport>();

        var Member1 = new MemberModel()
        {

            MemberShipCode = "A",MemberShipYear = "111"
        };
        var Player1 = new PlayerModel()
        {
            MemberModelId = 12,PlayerName = "B",PlayerPayment = 1.2,};
        var SportPlayer1 = new PlayerSport()
        {
            PlayerModelId = 1,SportId = 2
        };
        var Sport1 = new Sport()
        {

            SportCaegory = new SportCaegory()
            {
                SportPrice = 12,SportType = "tY"
            },SportName = "Name1",SportPrice = 13,SportType = "ww"
        };


        db.Insert(Member1);
        db.Insert(Player1);
        db.Insert(Sport1);
        db.Insert(SportPlayer1);

        Member1.MembershipNPlayers = new List<PlayerModel> { Player1 };
        Player1.Sports = new List<Sport> { Sport1 };
        Sport1.Players = new List<PlayerModel>() { Player1 };

        db.UpdateWithChildren(Member1);
        db.UpdateWithChildren(Sport1);
        db.UpdateWithChildren(Player1);


        var M = db.GetWithChildren<MemberModel>(Member1.Id);
        var P = db.GetWithChildren<PlayerModel>(Player1.Id);

截屏：