master detail / multi table best practice/method Add to Entity Framework

.net entity-framework linq linq-to-entities

Question

My table structure is this

Orders
------ 
Id int identity
OrderDate smalldatetime
OrderStatusid tinyint

Products
--------
Id int identity
Name varchar(50)

OrderDetails
------------
Id int identity
OrderId int (fkey)
ProductId int (fkey)
Amount decimal
Rate decimal

I am trying to an insert operation using Entity Framework using the code below
Is this the best way to do the insert?
I am not happy with the way I am getting the full product item from the context object, instead of being able to just assign a simple productId value

using (MyContextEntities ctx = new MyContextEntities())
{
    Orders newOrder = new Orders()
    {
    Name = "Gayle Wynand",
    OrderDate = DateTime.Now,
    IsComplete = true,
    Comments = "test",
    OrderStatusId = 2,
    IsActive = true
    };
    OrderDetails ode = new OrderDetails();
    ode.Products = ctx.Products.First(p => p.Id == 2); // any other way?
    ode.Quantity = 2;
    ode.Rate = 5.2;
    newOrder.OrderDetails.Add(ode);

    OrderDetails ode2 = new OrderDetails();
    ode2.Products = ctx.Products.First(p => p.Id == 3); // any other way?
    ode2.Quantity = 3;
    ode2.Rate =6.5;
    newOrder.OrderDetails.Add(ode2);


    ctx.AddToOrders(newOrder);
    ctx.SaveChanges();
}

Is this the correct way to do the master detail insert or is there a better/another way.

1
7
7/21/2009 12:39:03 PM

Accepted Answer

What you are doing now will work just fine.

If you would like to avoid doing a database query when assigning ode.Products, then you could use the following alternative:

// substitute your actual qualified entity set name
ode.ProductsReference.EntityKey = 
    new EntityKey("MyEntities.ProductsEntitySetName", "Id", 2);

This is faster, but less readable. Also, the Products property will be null until you Load it. But for an insert, this is often OK.

2
7/21/2009 12:39:13 PM

Popular Answer

Another approach would be to use Stub Objects rather than EntityKeys i.e.

var product = new Product {ID = 2};
ctx.AttachTo("Products", product);
ode.Product = product;

etc. As an added bonus this code will work with POCO objects too in the future.

See this blog post for more information on that technique.



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