CODEWITHSUNDEEP
entity-framework
Stéphan
Stéphan

Reputation: 327

DDD and Entity Framework: Pulling children from aggregate root

This one is driving me nuts! For simplicity, I'm not gonna put up the entire code that is used for our DDD but simply expose what I've tried and explain what isn't working.

I have a simple database structure:

Products (holds product data)
Orders (holds entered orders)
OrderProducts (ref table between Orders and Product)

I have an Order aggregate root and I want to pull out the product count of one simple Order.

I fetch my Order by id which results in an EF lambda: 

var order = _orderRepository.Get(orderId);

Then, I try to pull the count of products in that order using: 

var count = order.OrderProducts.Count();

This line chokes up when an order has A LOT a records because, it's fetching all of them. Fine. So, I'm refining it a bit by adding some filters to the products I want to count from within my order. A product has a couple of properties which include a type (so, there's a type ID). So, now I'm trying this:

//This is trimming down my results to about a dozen products)
var count = order.OrderProduct
                 .Where(op=>op.Product.TypeId == 2)
                 .Count();

If I use Linqpad to see what kind of SQL is generated, to my surprise, it's still loading ALL the OrderProducts from this order!

How can I force it to apply the filter in the query directly?

Upvotes: 1

Views: 353

Answers (1)

Corey Adler
Corey Adler

Reputation: 16149

It's loading all of them because once you touch the navigation property (i.e. order.OrderProducts) eager loading kicks in and loads all of them (i.e. even the ones that you don't want). Your only option to reduce that would be to query the database itself given the orderID. Maybe something like:

_orderProductRepository.Where(p => p.OrderID == orderId && p.Product.TypeID == 2);

Upvotes: 1

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