当我尝试加载父实体的子实体时,它会加载默认值。如果我尝试显式加载它会抛出异常 违反了多重性约束。 “CodeFirstNamespace.Association_Customer”关系的角色“Association_Customer_Target”具有多重性1或0..1。检索复杂图形的子实体时抛出此异常。
我有一个图表关联,它有一个子实体客户,关系为一到零或一个,并且有独立关联。* 主键 * 共享。我正在使用EF6。延迟加载已启用。
public class Association
{
public virtual long Id { get; set; }
public virtual string ExternalId { get; set; }
public virtual int OrganizationId { get; set; }
public virtual AssociationType AssociationType { get; set; }
public virtual Customer Customer {get; set;}
public Association()
{
Customer = new Customer();
}
}
客户类。
public class Customer
{
public virtual long Id { get; set; } //Shared primary key
public virtual ICollection<Item> Items {get; set;}
public virtual ICollection<Complaint> Complaints {get; set;}
public customer()
{
Items = new List<Item>();
Complaints = new List<Complaint>();
}
}
映射是单向的:
public class AssociationMapping:EntityTypeConfiguration<Association>
{
public AssociationMapping() : base()
{
HasKey(x => x.Id);
Property(x => x.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
Property(x => x.ExternalId).IsRequired();
Property(x => x.OrganizationId).IsRequired();
Property(x => x.AssociationType);
HasOptional(x => x.Customer).WithRequired().WillCascadeOnDelete();
}
}
public class CustomerMapping : EntityTypeConfiguration<Customer>
{
public CustomerMapping ():base()
{
HasKey(x => x.Id);
Property(x => x.Id);
HasMany(x => x.Items)
.WithOptional()
.HasForeignKey(key => key.CustomerId)
.WillCascadeOnDelete();
HasMany(x => x.Complaints)
.WithOptional()
.HasForeignKey(key => key.CustomerId)
.WillCascadeOnDelete();
}
}
当我加载我的关联实体时,它完全加载,但当我尝试显式加载Customer时,子实体Customer加载了默认值,它会抛出异常。
var dbassociation = Single<Association>(x => x.OrganizationId== asso.organizationId && x.ExternalId == asso.ExternalId && x.AssociationType == asso.AssociationType);
dbassociation.Customer = Single<Customer>(x => x.id == dbassociation.id);
[更新:单一方法]
public TEntity Single<TEntity>(System.Linq.Expressions.Expression<Func<TEntity, bool>>criteria) {
return Context.Set<TEntity>().SingleOrDefault(criteria); }
出于测试目的,我试图通过删除关联类中的Customer属性上的虚拟来尝试加载并尝试跟随但是它会抛出相同的范围
Context.Configuration.LazyLoadingEnabled = false;
Context.Entry<Association>(dbassociation).Reference<Customer>(pa => pa.Customer).Load();
我也尝试过抛出同样的异常
var dbassociation = Context.Set<Association>().Include("Customer").SingleOrDefault(x => x.OrganizationId== asso.organizationId && x.ExternalId == asso.ExternalId && x.AssociationType == asso.AssociationType);
现在我得出结论,虽然我使用不同的方法来检索异常是一样的。问题在于我猜测的映射。感谢您的意见和建议。
答案 0 :(得分:11)
尝试删除
Customer = new Customer();
来自Association
构造函数的。实例化导航引用是已知问题的来源(与实例化空导航集合相反,这很好)。这就是为什么你得到一个Customer
默认值的原因。我不确定它是否也解释了异常,但我可以想象当Association
被加载并附加到上下文以及默认构造函数创建的未初始化Customer
时,EF检测到相关实体无效密钥:具有(我假设)密钥值Association
的{{1}}和具有密钥!=0
的相关Customer
(因为它从未被初始化为其他值) 。但是,在共享主键关联中,两个键值必须匹配。因为它们没有,它可能会导致异常(但是这个异常并不能很好地指出问题的根源。)
只是一个猜测。