如何修复:关系约束中的从属角色和主要角色中的属性数必须相同？

Question

我正在使用实体框架4.3.1对SQL Server 2012数据库,我正在使用POCO方法.我收到以下错误,我想知道是否有人可以解释如何解决它:

ModelValidationException

在模型生成期间检测到一个或多个验证错误:\ tSystem.Data.Entity.Edm.EdmAssociationConstraint ::关系约束中的从属角色和主要角色中的属性数必须相同.

没有InnerException任何进一步的信息.

我无法更改数据库架构,这有点奇怪,但这里是......

• **是主键(注意我有复合主键)
• (FK)表示外键

以下是表格(如果它有助于我发布SQL以生成它们,但我不认为这些表实际上是问题,因为例外是在模型的验证中):

One
-
**OneId int not null
**TwoId int not null (FK)
**ThreeId int not null (FK)
Name nvarchar(50) not null

Two
-
**TwoId int not null
**ThreeId int not null (FK)
Name nvarchar(50) not null

Three
-
**ThreeId not null
Name nvarchar(50) not null

这是实体(注意我在模型中包含外键但不是那个非常标准的):

public class Three
{
    public int ThreeId { get; set; }
    public string Name { get; set; }
    public virtual ICollection<Two> Twos { get; private set; }
    public virtual ICollection<One> Ones { get; private set; }

    public void AddOne(One one)
    {
        if (one == null)
            throw new ArgumentNullException("two");

        if (Ones == null)
            Ones = new List<One>();

        if (!Ones.Contains(one))
            Ones.Add(one);

        one.Three = this;
    }

    public void AddTwo(Two two)
    {
        if (two == null)
            throw new ArgumentNullException("two");

        if (Twos == null)
            Twos = new List<Two>();

        if (!Twos.Contains(two))
            Twos.Add(two);

        two.Three = this;
    }
}

public class Two
{
    public int TwoId { get; set; }
    public int ThreeId { get; set; }
    public string Name { get; set; }
    public virtual Three Three { get; set; }
    public virtual ICollection<One> Ones { get; private set; }

    public void AddOne(One one)
    {
        if (one == null)
            throw new ArgumentNullException("two");

        if (Ones == null)
            Ones = new List<One>();

        if (!Ones.Contains(one))
            Ones.Add(one);

        one.Two = this;
    }
}

public class One
{
    public int OneId { get; set; }
    public int TwoId { get; set; }
    public int ThreeId { get; set; }
    public virtual Two Two { get; set; }
    public virtual Three Three { get; set; }
}

这是数据上下文:

public class DbCtx : DbContext
{
    public DbCtx(string connectionString)
        : base(connectionString)
    {
        Ones = Set<One>();
        Twos = Set<Two>();
        Threes = Set<Three>();
    }

    public DbSet<One> Ones { get; private set; }
    public DbSet<Two> Twos { get; private set; }
    public DbSet<Three> Threes { get; private set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        var one = modelBuilder.Entity<One>();
        one.ToTable("One");

        one.HasKey(d => new
                            {
                                d.OneId,
                                d.TwoId,
                                d.ThreeId
                            });

        one.Property(d => d.OneId)
            .HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);

        one.HasRequired(t => t.Two)
            .WithMany(s => s.Ones)
            .HasForeignKey(t => t.TwoId);

        one.HasRequired(t => t.Three)
            .WithMany(s => s.Ones)
            .HasForeignKey(t => t.ThreeId);

        var two = modelBuilder.Entity<Two>();
        two.ToTable("Two");

        two.HasKey(d => new
                            {
                                d.TwoId,
                                d.ThreeId
                            });

        two.Property(p => p.TwoId)
            .HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);

        two.HasRequired(t => t.Three)
            .WithMany(s => s.Twos)
            .HasForeignKey(t => t.ThreeId);

        var three = modelBuilder.Entity<Three>();
        three.ToTable("Three");
        three.HasKey(s => s.ThreeId);

        three.Property(p => p.ThreeId)
            .HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);

        base.OnModelCreating(modelBuilder);
    }
}

最后,这是导致异常的代码片段:

using (var ctx = new DbCtx(@"....."))
{
    Console.WriteLine(ctx.Twos.Count());
}

Answer 1

错误的原因是模型中的关系配置不正确.这不正确:

    one.HasRequired(t => t.Two)
        .WithMany(s => s.Ones)
        .HasForeignKey(t => t.TwoId);

    one.HasRequired(t => t.Three)
        .WithMany(s => s.Ones)
        .HasForeignKey(t => t.ThreeId);

它应该是:

    one.HasRequired(t => t.Two)
        .WithMany(s => s.Ones)
        .HasForeignKey(t => new { t.TwoId, t.ThreeId });

因为依赖的FK必须包含主PK的所有列.您还必须从删除导航属性Three来One.