EF4.3创建一对一关系失败 [英] EF4.3 create one to one or zero relationship failed

问题描述

我使用EF4.3创建1到1 ... 0关系，但它抛出

的例外操作失败，因为表'TestAs'上已经存在名称为'IX_id'
的索引或统计信息

代码如下

 命名空间ConsoleApplication1 
 {
类程序
 {
 static void Main string [] args）
 {
 using（myContext context = new myContext（））
 {
 TestA tA = new TestA（）; 
 TestB tB = new TestB（）; 
 TestC tC = new TestC（）; 
 context.testA.Add（tA）; 
 context.testB.Add（tB）; 
 context.testC.Add（tC）; 
 context.SaveChanges（）; 
} 
} 
} 
 
 class TestA 
 {
 public int id {get;组; } 
 // public TestB NavB {get;组; } 
 // public TestC NavC {get;组; } 
} 
 
 class TestB 
 {
 public int id {get;组; } 
 public TestA NavA {get;组; } 
} 
 
 class TestC 
 {
 public int id {get;组; } 
 public TestA NavA {get;组; } 
} 
 
 class myContext：DbContext 
 {
 public DbSet< TestA> testA {get;组; } 
 public DbSet< TestB> testB {get;组; } 
 public DbSet&Test;> testC {get;组; 
 
 protected override void OnModelCreating（DbModelBuilder modelBuilder）
 {
 modelBuilder.Entity< TestB>（）。HasOptional（x => x.NavA）.WithRequired（）; 
 modelBuilder.Entity< TestC>（）。HasOptional（x => x.NavA）.WithRequired（）; 
} 
} 
} 
  

任何人都可以帮助？ p>

解决方案

在 OnModelCreating WithRequired c $ c>方法由 WithOptionalPrincipal ：

  protected override void OnModelCreating DbModelBuilder modelBuilder）
 {
 modelBuilder.Entity< TestB>（）。HasOptional（x => x.NavA）.WithOptionalPrincipal（）; 
 modelBuilder.Entity< TestC>（）。HasOptional（x => x.NavA）.WithOptionalPrincipal（）; 
} 
  

（如果A将是您将使用的主要实体 WithOptionalDependent 。）

编辑

在您的意见之后，我认为看到添加两个类TestD和TestE的效果会很有趣，给出了两个导航属性TestD和TestE，并在您的模型中执行此操作：

  modelBuilder.Entity< TestB>（）。HasOptional（x => x.NavA）.WithOptionalPrincipal（）; 
 modelBuilder.Entity< TestC>（）。HasOptional（x => x.NavA）.WithOptionalPrincipal（）; 
 modelBuilder.Entity< TestA>（）。HasRequired（x => x.NavD）; 
 modelBuilder.Entity< TestA>（）。HasRequired（x => x.NavE）;表B现在有四个外键：B和C（可空），D和E（不可空）。我认为后者是你想要的。
 
I use EF4.3 to create 1 to 1...0 relationship, but it throw an exception of 

  
"The operation failed because an index or statistics with name 'IX_id'
  already exists on table 'TestAs'"
The code as below
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            using (myContext context = new myContext())
            {
                TestA tA = new TestA();
                TestB tB = new TestB();
                TestC tC = new TestC();
                context.testA.Add(tA);
                context.testB.Add(tB);
                context.testC.Add(tC);
                context.SaveChanges();
            }
        }
    }

    class TestA
    {
        public int id { get; set; }
        //public TestB NavB { get; set; }
        //public TestC NavC { get; set; }
    }

    class TestB
    {
        public int id { get; set; }
        public TestA NavA { get; set; }
    }

    class TestC
    {
        public int id { get; set; }
        public TestA NavA { get; set; }
    }

    class myContext : DbContext
    {
        public DbSet<TestA> testA { get; set; }
        public DbSet<TestB> testB { get; set; }
        public DbSet<TestC> testC { get; set; }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Entity<TestB>().HasOptional(x => x.NavA).WithRequired();
            modelBuilder.Entity<TestC>().HasOptional(x => x.NavA).WithRequired();
        }
    }
}
Anyone can help?
解决方案
Replace WithRequired in your OnModelCreating method by WithOptionalPrincipal:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
  modelBuilder.Entity<TestB>().HasOptional(x => x.NavA).WithOptionalPrincipal();
  modelBuilder.Entity<TestC>().HasOptional(x => x.NavA).WithOptionalPrincipal();
}
(If A would be the principal entity you'd use WithOptionalDependent.)

EDIT

After your comments I think it would be interesting to see the effect of adding two classes TestD and TestE, giving A two navigation properties TestD and TestE and do this in your model:
modelBuilder.Entity<TestB>().HasOptional(x => x.NavA).WithOptionalPrincipal();
modelBuilder.Entity<TestC>().HasOptional(x => x.NavA).WithOptionalPrincipal();
modelBuilder.Entity<TestA>().HasRequired(x => x.NavD);
modelBuilder.Entity<TestA>().HasRequired(x => x.NavE);
Table A now has four foreign keys: to B and C (nullable), to D and E (not nullable). I think the latter is what you want.

                        
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