实体框架更新两个数据库

Question

As I've mentioned in a couple other questions, I'm currently trying to replace a home-grown ORM with the Entity Framework, now that our database can support it.

Currently, we have certain objects set up such that they are mapped to a table in our internal database and a table in the database that runs our website (which is not even in the same state, let alone on the same server). So, for example:

Part p = new Part(12345);
p.Name = "Renamed part";
p.Update();

will update both the internal and the web databases simultaneously to reflect that the part with ID 12345 is now named "Renamed part". This logic only needs to go one direction (internal -> web) for the time being. We access the web database through a LINQ-to-SQL DBML and its objects.

I think my question has two parts, although it's possible I'm not asking the right question in the first place.

1. Is there any kind of "OnUpdate()" event/method that I can use to trigger validation of "Should this be pushed to the web?" and then do the pushing? If there isn't anything by default, is there any other way I can insert logic between .SaveChanges() and when it hits the database?
2. Is there any way that I can specify for each object which DBML object it maps to, and for each EF auto-generated property which property on the L2S object to map to? The names often match up, but not always so I can't rely on that. Alternatively, can I modify the L2S objects in a generic way so that they can populate themselves from the EF object?

Answer 1

听起来像是Sql Server复制的工作 。

Answer 2

您不需要像问题2那样将两者相互连接在一起。只需将两个单独的数据库具有自己的EF或L2S模型，然后使用具有域对象的存储库将它们抽象化即可。

Answer 3

This is the solution I ended up going with. Note that the implementation of IAdvantageWebTable is inherited from the existing base class, so nothing special needed to be done for EF-based classes, once the T4 template was modified to inherit correctly.

public partial class EntityContext
{
    public override int SaveChanges(System.Data.Objects.SaveOptions options)
    {
        var modified = this.ObjectStateManager.GetObjectStateEntries(EntityState.Modified | EntityState.Added); // Get the list of things to update
        var result = base.SaveChanges(options); // Call the base SaveChanges, which clears that list.
        using (var context = new WebDataContext()) // This is the second database context.
        {
            foreach (var obj in modified)
            {
                var table = obj.Entity as IAdvantageWebTable;
                if (table != null)
                {
                    table.UpdateWeb(context); // This is IAdvantageWebTable.UpdateWeb(), which calls all the existing logic I've had in place for years.
                }
            }
            context.SubmitChanges();
        }
        return result;
    }
}