EF5多对多更新断开连接的场景

Question

我还没有找到一个很好的解决方案来解决这个问题（类似这里的门票EF5 update disconnected graph (n-tier) one-to-many）。

我发现并遵循此示例：http://entityframeworktutorial.net/update-many-to-many-entities-in-entity-framework.aspx#.UTBeTDBhif8。

这工作得很好，但它创建了相关实体的副本（使用sql profiler，我看到了Insert into RelatedEntities ..我只希望在MyEntities_Related连接表上插入/更新，但我不明白为什么EF使得在RelatedEntities表:(

这里插入是我的代码：

public void AddOrUpdate(MyEntity entity) { 
    var dbEntity = _context.MyEntities 
     .Include(e => e.RelatedEntitis) 
     .Where(e => e.ID == entity.ID) 
     .SingleOrDefault(); 

    var newRelated = entity.RelatedEntitis.ToList<RelatedEntity>(); 
    var dbRelated = dbEntity.RelatedEntity.ToList<RelatedEntity>(); 

    _context.Entry(dbEntity).CurrentValues.SetValues(entity); 

    var comparer = new EqualityComparer(); 
    var addedRelated = newRelated.Except(dbRelated, comparer).ToList<RelatedEntity>(); 
    var deletedRelated = dbRelated.Except(newRelated, comparer).ToList<RelatedEntity>(); 

    addedRelated.ForEach(e => dbEntity.RelatedEntity.Add(e)); 
    deletedRelated.ForEach(e => dbEntity.RelatedEntity.Remove(e)); 
} 

public class EqualityComparer : IEqualityComparer<RelatedEntity> 
{ 
    public int GetHashCode(RelatedEntity obj) 
    { 
     return (obj == null) ? 0 : obj.ID.GetHashCode(); 
    } 

    public bool Equals(RelatedEntity x, RelatedEntity y) 
    { 
     if (ReferenceEquals(x, y)) return true; 
     if (x == null || y == null) return false; 
     return x.ID == y.ID; 
    } 
} 

DB模式是这样的：

|------------------| 
| Table MyEntities | 
|------------------| 
| int ID //PK  | 
|------------------| 


|--------------------------| 
| Table MyEntities_Related | 
|--------------------------| 
| int MyEntityID   | 
| int RelatedID   | 
|--------------------------| 


|-----------------------| 
| Table RelatedEntities | 
|-----------------------| 
| int RelatedID //PK | 
| string Name   | 
|-----------------------| 

任何帮助表示赞赏:)

Answer 1

SOLUTION 我不知道这是否是最好的，但它为我工作，我认为它的意义。 EF创建relatedentities的副本，因为他们是超然的， 我改变了我的代码是这样的：

public void AddOrUpdate(MyEntity entity) { 
    var dbEntity = _context.MyEntities 
     .Include(e => e.RelatedEntitis) 
     .Where(e => e.ID == entity.ID) 
     .SingleOrDefault(); 

    //replace entities with those taken from the context 
    var relatedEntities = _context.RelatedEntities; 
    var detachedEntities = entity.RelatedEntities; 
    entity.RelatedEntities = new List<RelatedEntity>(); 
    foreach (var ent in detachedEntities) 
    { 
     entity.RelatedEntities.Add(relatedEntities .Where(e => e.ID == hop.ID).SingleOrDefault()); 
    } 

    var newRelated = entity.RelatedEntitis.ToList<RelatedEntity>(); 
    var dbRelated = dbEntity.RelatedEntity.ToList<RelatedEntity>(); 

    _context.Entry(dbEntity).CurrentValues.SetValues(entity); 
    _context.Entry(dbEntity.RelatedEntity).CurrentValues.SetValues(entity.RelatedEntitis); 

    var comparer = new EqualityComparer(); 
    var addedRelated = newRelated.Except(dbRelated, comparer).ToList<RelatedEntity>(); 
    var deletedRelated = dbRelated.Except(newRelated, comparer).ToList<RelatedEntity>(); 

    addedRelated.ForEach(e => dbEntity.RelatedEntity.Add(e)); 
    deletedRelated.ForEach(e => dbEntity.RelatedEntity.Remove(e)); 
}