c# - 实体框架：在 6.1.1 中检查实体的所有关系失败

Question

在使用实体框架版本时，我已经成功使用此代码检查所有关系。5. （来自 yildizm85，Entity Framework: Check all relationship of an entity for foreign key use）

public bool IsUnitNameInRelationship(UnitName unitName)
{
  bool hasRelation = false;
  var allRelatedEnds = ((IEntityWithRelationships)unitName).RelationshipManager.GetAllRelatedEnds();
  foreach (var relatedEnd in allRelatedEnds)
  {
    if (relatedEnd.GetEnumerator().MoveNext())
    {
      hasRelation = true;
      break;
    }
  }
  return hasRelation;
}

升级到 EF 6.1.1 后失败。错误信息是：

Unable to cast object of type 'System.Data.Entity.DynamicProxies.UnitName_F023365757AB452259D6FFA34E2DC147E423592BFB4A49619F41A60AA3AF5ECA' to type 'System.Data.Objects.DataClasses.IEntityWithRelationships'.

使用 EF 6.1.1 检查所有关系是否有更好的方法？

Answer 1

IEntityWithRelationships我在将实体的动态代理实例转换为EF 6.1.3的接口时遇到了同样的问题！而且由于我没有父级的所有关联实体的导航属性，所以我想出了这个基于反射的代码来最终获取RelationshipManager实例：

var entityProxy = DbContext.FooBars.First(fb => fb.Id == someId);
var proxyType = entityProxy.GetType();

var wrapperField = proxyType.GetField("_entityWrapper");
var wrapper = wrapperField.GetValue(entityProxy);
var wrapperType = wrapper.GetType();

var relManProp = wrapperType.GetProperty("RelationshipManager");
Debug.Assert(relManProp != null, nameof(relManProp) + " != null");
var relMan = (RelationshipManager)relManProp.GetValue(wrapper);

var allEnds = relMan.GetAllRelatedEnds();
foreach (var relatedEnd in allEnds)
{
    Debug.Print("RELATIONSHIP-NAME:" + relatedEnd.RelationshipName);
}