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c#asp.net-mvc-3linqlinq-to-sql
bplattenburg
bplattenburg

Reputation: 696

How do I hook up classes to my Linq-to-Sql?

Linq / Linq-to-Sql / C# newbie question, but I can't seem to find any useful information on it. It is possible I'm not phrasing the question correctly. Any help appreciated.

So, I have some existing Database tables, and I have generated the DBML file from them. I have the partial classes and the DataContext. How can I connect my Entity classes back to this?

Am I just missing something very obvious?

Thanks

Upvotes: 0

Views: 177

Answers (1)

D Stanley
D Stanley

Reputation: 152521

If you want to keep your Entity classes separate from your partial DAO classes (which is a good thing for non-trivial applications), the most straightforward way is to create a mapping layer between the two (e.g. PropertyA in your DAO class is mapped to PropertyB in your Entity class).

If most of the field names/types are identical between the two layers, one way to save a lot of redundant coding is to use a mapping library like AutoMapper. It handles identical properties easily and can be configured to handle non-identical properties without too much effort in most cases.

In an MVC project I typically do this in the Repository. I will have Map() functions that take one type of object and create another. For example, to map a data-layer Order class to a domain-layer Order class:

public Domain.Order GetOrder(int orderID)
{
    Data.Order order = context.Orders.Where(o => o.OrderID = orderID);  // 
    Domain.Order newOrder = Map(order);
    return newOrder;
}

public Domain.Order Map(Data.Order order)
{
    if (!UsingAutomapper)
    {
        // raw way
        Domain.Order newOrder = new Domain.Order
                           {
                               ID         = order.OrderID,
                               Number     = order.OrderNumber,
                               OrderDate  = order.OrderDate
                           };
        return newOrder;
    }
    else  // let AutoMapper do the dirty work
    {
        return Mapper.Map(order);
    }
}

Upvotes: 2

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