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对于所有反射专家，我需要一些帮助。我正在研究一种通用方法，以便能够在使用 CodeFirst 和 EF5 的 MVC 应用程序中使用分层数据分配。用户将对父对象（源）应用更改，并且此方法将填充子对象（目标）。它没有像我预期的那样工作。任何指针将不胜感激。

下面的方法“CopyEntity”旨在获取具有子实体的源实体并更新相同类型和结构的目标实体。我们只希望更新那些继承基本类型“关联”并且成员上没有“NoInherit”属性的实体。并非每个属性都会从“协会”更新

public class ClassCode : Inheritable<ClassCode>
{

    // Base Properties ----------------------------------
    public int LobId { get; set; }
    public virtual LOB LOB { get; set; }
    public bool IsVirtual { get; set; }
    //public string Name { get; set; }
    public string Description { get; set; }

    [Required(ErrorMessage = "Select Code")]
    public string Code { get; set; }
    //enable to force recreation of the database
    public string IID { get; set; }

    public virtual ICollection<ClassSubjectivityAssoc> Subjectivities{ get; set; }
}

public class ClassSubjectivityAssoc : Association
{
    [Column("SubjectivityId")]
    public override int AssociationId { get; set; }

    [ForeignKey("AssociationId")]
    public virtual Subjectivity Subjectivity { get; set; }

    public int ClassCodeId { get; set; }
    [ForeignKey("ClassCodeId")]
    public virtual ClassCode ClassCode { get; set; }
}

public abstract class Association  : BaseEntity
{
    public DateTime Start { get; set; }
    public DateTime? End { get; set; }
    public bool IsCurrent { get; set; }
    public int Order { get; set; }
    public bool BreakInheritance { get; set; }
    public int? InhId { get; set; }
    public virtual ClassCode InhClass { get; set; }
    public int CodeId { get; set; }
    [ForeignKey("ClassCodeId")]
    public virtual Code ClassCode { get; set; }
    public abstract int AssociationId {get; set;}
}

public class BaseEntity
{
    private static DateTime CREATE_DATE
    {
        get { return DateTime.Now; }
    }

    [NoInherit]
    public int Id { get; set; }

    [NoInherit]
    public string CreatedBy { get; set; }
    [NoInherit]
    public DateTime Created { get; set; }

    [NoInherit]
    public string LastModifiedBy { get; set; }
    [NoInherit]
    public DateTime LastModified { get; set; }

    public bool IsActive { get; set; }
}

protected void CopyEntity(Inheritable<T> source, Inheritable<T> target)
{
    Type sourceType = source.GetType();
    Type targetType = target.GetType();
    // ensure that the types can be assigned to one another
    //if (!targetType.IsAssignableFrom(sourceType)) return;

    // loop through the properties of the source system
    foreach (PropertyInfo sourceMember in sourceType.GetProperties().Where(sourceMember => sourceMember.GetCustomAttribute(typeof(NoInheritAttribute)) == null))
    {
        var targetMember = targetType.GetProperty(sourceMember.Name);
        // if the property doesn't exist in the target, let's get out
        if (targetMember == null) continue;

        // check if this property is a Collection
        bool isCollection = (sourceMember.PropertyType.IsGenericType && sourceMember.PropertyType.GetInterfaces().Any(x =>
                                      x.IsGenericType &&
                                      x.GetGenericTypeDefinition() == typeof(IEnumerable<>)));

        // if we are not dealing with associations, let's get outta herre
        if (!(isCollection
                  ? sourceMember.PropertyType.GetGenericArguments().Single()
                  : sourceMember.PropertyType)
                 .IsSubclassOf(typeof(Association))) continue;

        if (isCollection)
        {
            IEnumerable<Association> targetCollection = (IEnumerable<Association>) targetMember.GetValue(target);
            // Loop through the collection and evaluate
            foreach (Association sourceAssociation in (IEnumerable) sourceMember.GetValue(source))
            {
                Association targetAssociation =
                    targetCollection.SingleOrDefault(t => t.AssociationId == sourceAssociation.AssociationId);
                CopyAssociation(sourceAssociation, targetAssociation);
            }
        }
        else
        {
            Association sourceAssociation = (Association) sourceMember.GetValue(source);
            Association targetAssociation = (Association) targetMember.GetValue(target);
            CopyAssociation(sourceAssociation, targetAssociation);
        }
    }
}

问题是：它似乎没有正确地遍历子对象并且没有像我预期的那样更新目标。寻找输入和建议，因为我不像我想要的那样精通反射。

更新：2012 年 12 月 6 日

好的，所以我相信我已经找到了问题，但仍在寻找解决方案。这个问题来自我团队的另一个开发人员，假设对象模型是合理的。但是，我们当前正在测试的实体似乎没有从数据库中检索种子值。

尽管从实体模型正确创建了表并且从 dbSeed() 方法正确加载了数据，但在定义此关联的 OnModelCreating() 方法中没有定义任何内容。我可以从数据库中运行一条选择语句并获取正确的数据。似乎实体模型外键关联可能无效，从而阻止了正确的数据检索。任何帮助将不胜感激。

更新：好的，终于检索到正确的数据。这终于做到了。

    modelBuilder.Entity<ClassSubjectivityAssoc>()
                .HasRequired(c => c.ClassCode)
                .WithMany(u => u.Subjectivities)
                .HasForeignKey(f => f.ClassCodeId);
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2 回答 2

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我不确定我是否理解这个问题，但似乎你只需要确保它sourceMember是一个Association（或后代）或一个Association.

您可以通过将结果值转换为 Association 并检查转换是否成功，以一种快速而肮脏的方式做到这一点，对于简单的属性如下所示：

Association sourceAssociation = sourceMember.GetValue(source) as Association;
if (sourceAssociation != null) // the source is a valid Association
{
   Association targetAssociation = targetMember.GetValue(target) as Association;
   if (targetAssociation != null) // the destionation too
   {
        CopyAssociation(sourceAssociation, targetAssociation);
   }
}

并且对于集合也有类似的代码

您显示的方法不会下降对象树，因此它仅适用于Association直接附加到实体的对象。

于 2012-12-05T16:29:03.683 回答
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有关解决方案，请参阅原始帖子“更新”。

于 2012-12-06T16:06:46.043 回答