与Entity-Framework-4.1的关系和外键错误

我遇到如下描述的问题：

One or more validation errors were detected during model generation:

System.Data.Edm.EdmAssociationType: : Multiplicity conflicts with the referential constraint in Role 'CorpQuestionA_CorpQAnswer_Source' in relationship 'CorpQuestionA_CorpQAnswer'. Because all of the properties in the Dependent Role are non-nullable, multiplicity of the Principal Role must be '1'.

我的数据库作为屏幕截图pic:

实体定义如下：

public class CorpQuestionA 
{ 
    [Key] 
    public Guid cqua_QuestionId { get; set; } 
    public Guid cqua_CorpId { get; set; } 
    [MaxLength] 
    public string cqua_Question { get; set; } 
    public DateTime cqua_Date { get; set; } 
    public Boolean cqua_IsAnswer { get; set; } 

    [ForeignKey("cqua_CorpId")] 
    public virtual CorpRegInfo510112 CorpRegInfo510112 { get; set; } 
    public virtual CorpQAnswer CorpQAnswer { get; set; } 
} 


public class CorpQAnswer 
{ 
    [Key] 
    public Guid cqan_QuestionId { get; set; } 
    public string cqan_Answer { get; set; } 

    [ForeignKey("cqan_QuestionId")] 
    public virtual CorpQuestionA CorpQuestionA { get; set; } 
} 

然后是ProjectDataEntities文件：

public class ProjectDataEntities : DbContext 
{ 
    public DbSet<CorpQuestionA> Tbl_CorpQuestionAs { get; set; } 
    public DbSet<CorpQAnswer> Tbl_CorpQAnswers { get; set; } 

    protected override void OnModelCreating(DbModelBuilder modelBuilder) 
    { 
        base.OnModelCreating(modelBuilder); 
        modelBuilder.Conventions.Remove<IncludeMetadataConvention>(); 

        modelBuilder.Entity<CorpQuestionA>().ToTable("tbl_CorpQuestionA"); 
        modelBuilder.Entity<CorpQAnswer>().ToTable("tbl_CorpQAnswer"); 

        //Todo: Add custom mapping rules here... 
        modelBuilder.Entity<CorpQuestionA>().HasOptional(p => p.CorpQAnswer).WithOptionalPrincipal(x => x.CorpQuestionA);//.Map(p => p.MapKey("cqua_QuestionId")); 
    } 
}

---

等待帮助时，thx将按如下方式更改共享主键

protected override void OnModelCreating(DbModelBuilder modelBuilder) 
{ 
    base.OnModelCreating(modelBuilder); 
    modelBuilder.Conventions.Remove<IncludeMetadataConvention>(); 

    modelBuilder.Entity<CorpQuestionA>().ToTable("tbl_CorpQuestionA"); 
    modelBuilder.Entity<CorpQAnswer>().ToTable("tbl_CorpQAnswer"); 

    modelBuilder.Entity<CorpQuestionA>().HasOptional(p => p.CorpQAnswer)
       .WithRequired(x => x.CorpQuestionA);
}

模型创建时受保护的覆盖无效（DbModelBuilder modelBuilder）
{ 
基于模型创建（modelBuilder）；
modelBuilder.Conventions.Remove（）；
modelBuilder.Entity（）.ToTable（“tbl_CorpQuestionA”）；
modelBuilder.Entity（）.ToTable（“tbl_CorpQAnswer”）；
modelBuilder.Entity（）.has可选（p=>p.CorpQAnswer）
.需要（x=>x.CorpQuestionA）；
}

如下更改共享主键

protected override void OnModelCreating(DbModelBuilder modelBuilder) 
{ 
    base.OnModelCreating(modelBuilder); 
    modelBuilder.Conventions.Remove<IncludeMetadataConvention>(); 

    modelBuilder.Entity<CorpQuestionA>().ToTable("tbl_CorpQuestionA"); 
    modelBuilder.Entity<CorpQAnswer>().ToTable("tbl_CorpQAnswer"); 

    modelBuilder.Entity<CorpQuestionA>().HasOptional(p => p.CorpQAnswer)
       .WithRequired(x => x.CorpQuestionA);
}

模型创建时受保护的覆盖无效（DbModelBuilder modelBuilder）
{ 
基于模型创建（modelBuilder）；
modelBuilder.Conventions.Remove（）；
modelBuilder.Entity（）.ToTable（“tbl_CorpQuestionA”）；
modelBuilder.Entity（）.ToTable（“tbl_CorpQAnswer”）；
modelBuilder.Entity（）.has可选（p=>p.CorpQAnswer）
.需要（x=>x.CorpQuestionA）；
}

Try

modelBuilder.Entity（）.has可选（p=>p.CorpQAnswer）。带必填项（x=>x.CorpQuestionA）OnModelCreating

方法中，而不是

modelBuilder.Entity（）.haspoptional（p=>p.CorpQAnswer）。使用optionalPrincipal（x=>x.CorpQuestionA）非常感谢。如何选择你的帖子作为正确答案？我添加了评论作为答案。您可以接受：）Try
modelBuilder.Entity（）.hasportional（p=>p.CorpQAnswer）。WithRequired（x=>x.CorpQuestionA）OnModelCreating
方法中，而不是
modelBuilder.Entity（）.haspoptional（p=>p.CorpQAnswer）。使用optionalPrincipal（x=>x.CorpQuestionA）非常感谢。如何选择你的帖子作为正确答案？我添加了评论作为答案。你可以接受：）