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

.net entity-framework linq linq-to-entities


My table structure is this

Id int identity
OrderDate smalldatetime
OrderStatusid tinyint

Id int identity
Name varchar(50)

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;

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


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

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.

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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