EF6 如何判断DataContext有修改，以及如何放弃修改

如何判断DataContext有修改：

EF6的

using (var db = new Model1())
{
    if (db.ChangeTracker.HasChanges())
    {
        Console.WriteLine("Something has changed");
    }
}

EF5中：

public bool HasUnsavedChanges()
 {
    return this.ChangeTracker.Entries().Any(e => e.State == EntityState.Added
                                              || e.State == EntityState.Modified
                                              || e.State == EntityState.Deleted);
 }

EF4中为：

public Boolean HasUnsavedChanges()
    {
        return (this.ObjectContext().ObjectStateManager.GetObjectStateEntries(EntityState.Added | EntityState.Modified | EntityState.Deleted).Any());
    }

DataContext如何放弃修改的建议：

this is not supposed way to use context. Context is unit of work - do changes you really want to do and then save them. If you find that you don't want to save changes dispose the context and create a new one. The best practice is using context for one single logical operation. Sharing context or using static context is a bad practice and because of that there is no build in method to "reset" context - you must do it yourselves by exploring ObjectStateManager and reverting all changes (it can be quite complex task).

参考

Entity Framework 5 - DbContext Has Changes

Entity Framework 6.1 is context dirty