使用接口/抽象類與實體框架CodeFirst

Question

我有一個實體框架CodeFirst類（POCO）客戶端：

void context_SavingChanges(object sender, EventArgs e) 
{ 

    foreach (ObjectStateEntry entry in 
     ((ObjectContext)sender).ObjectStateManager.GetObjectStateEntries(
     EntityState.Added | EntityState.Modified | EntityState.Deleted)) 
    { 

     IMyContract myContract = entry.Entity as IMyContract; 
     if(myContract != null) 
     { 
      ... 
     } 
    } 
} 

Answer 1

你提到的代碼第一，但在同一時間，你正在處理的ObjectContext事件和鑄造發件人ObjectContext

試試這個：

public class MyContext : DbContext 
{ 
    private static EntityState[] states = new EntityState[] 
     { 
      EntityState.Added, 
      EntityState.Modified, 
      EntityState.Deleted, 
     }; 

    ... 

    public override int SaveChanges() 
    { 
     // If Entires<IMyContract> doesn't work use Entries() and check type 
     // inside the loop 
     foreach(var entry in ChangeTracker.Entries<IMyContract>() 
              .Where(e => states.Contains(e.State)) 
     { 
      ... 
     } 
    } 
}