Flattening with Projeciton(ProjectTo)

[crowz4k]

According to documentation (Flattening) AutoMapper can flatten structure.

    public class Order
    {
        public int Id { get; set; }
        public Order()
        {
            OrderLineItems = new List<OrderLineItem>();
        }

        public virtual Customer Customer { get; set; }
        public virtual  List<OrderLineItem> OrderLineItems { get; set; }
        
        public decimal GetTotal()
        {
            return OrderLineItems.Sum(li => li.GetTotal());
        }
    }

    public class OrderLineItem
    {
        public int Id { get; set; }
        public int ProductId { get; set; }
        public Product Product { get; set; }

        public int Quantity { get; set; }

        public decimal GetTotal()
        {
            return Quantity * Product.Price;
        }
    }

    public class Product
    {
        public int Id { get; set; }
        public decimal Price { get; set; }
        public string Name { get; set; }
    }

    public class OrderDto
    {
        public string CustomerName { get; set; }
        public decimal Total { get; set; }
    }

var result = await _context.Orders.AsQueryable()
                .ProjectTo<OrderDto>(_mapper.ConfigurationProvider)
                .ToListAsync();

But when I try to do that with SQLite and example from the documentation it does not work. Do Flattening work with ProjectTo?

[lbargaoanu]

It does work :) Check the execution plan.

[crowz4k]

Do I do something wrong?
Here is my sample repo -> sample repo

[lbargaoanu]

Start with the most basic example and work your way up. I'm sure you're missing smth.

[crowz4k]

You can't get simpler than this, this is from the documentation. You can see I added miniprofiler as well so I get the exact query that it is produced.

SELECT "c"."Name", "o"."Id", "o"."CustomerId"
FROM "Orders" AS "o"
LEFT JOIN "Customers" AS "c" ON "o"."CustomerId" = "c"."Id"

[jbogard]

You're using ProjectTo with a calculated method. That only works with some LINQ providers. Remove AutoMapper from the equation, use LINQ directly, and you'll see.

[crowz4k]

@jbogard Thank you, I wanted to try to do this with AutoMapper so when I pull back data I just want few columns not all, I thought I can use this with AutoMapper Flattening.
Actually, the real use-case is more complex (EF + SQLServer), I thought I could use ProjectTo