C# Entity Framework querying-CodePudding

I'm new to C# and have problem I would usually solve with a subquery, but unsure how to go about it here.

I have a table called Orders that has many OrderLines (the foreign key is on the OrderLines).

The OrderLines have a lot of data, but I'm only interested in the sum of all OrderLines.value for each Order.

In pseudocode I want something like

DbSet.(o:order => o)
     .Include(o => Sum(o.OrderLines.value)

What is the idiomatic way to do something like this?

CodePudding user response：

Something like this:

var ordersWithLineTotal = db.Set<Order>()
                            .Select(o => new { Order = o, LineTotal = o.OrderLines.Sum(l => l.LineTotal) })
                            .ToList();