How can I attach EF sub-entities to an EF entity? -

suppose have order entity , orderitem entity, , i'm trying details (including items) of several orders @ once.

i order , orderitem details using .include so:

var orders = db.orders                .include(o => o.orderitem)                .where(o => orderids.contains(o.id)); 

but, suppose can't use .include because it doesn't work.

instead, fetch of orders, , fetch of orderitems, this:

var orders = db.orders.where(o => orderids.contains(o.id));  var orderitems = db.orderitems.where(i => orderids.contains(i.orderid)); 

this give me orders , (separately) relevant orderitems. how "attach" orderitem objects relevant order objects navigation properties work correctly?

(in other words, how ensure order.orderitems , orderitem.order work without causing ef go fetch data database rather using i've retrieved).

about last question - how ensure order.orderitems , orderitem.order work without causing ef go fetch data database ... - can first .load() queries memory:

orders.load(); orderitems.load(); 

and use them through local property of context:

var qo = db.orders.local.where(...); var qoi = db.orderitems.local.where(...);