Wenxamarin - Web API

Question

I’m trying to make the code of the Post Api and I’m not able to save the information, since it comes from a relationship between two tables. It is a sales system, where I have two tables, one that is called Ordempedido, where is the customer information, form of payment and a second where is stored the details of this order as the products that the customer wants to buy, however when generating the Post Api I can only save part of the order which refers to the customer information and payment method and does not save the details of my order, that is, the products do not display.

// POST: api/OrdemPedidoes
    [ResponseType(typeof(OrdemPedido))]
    public IHttpActionResult PostOrdemPedido(OrderRequest orderRequest)
    {
        var details = new List<OrderDetailldTmp>();
        foreach (var detail in orderRequest.Detalhes)
        {
            var product = db.CadProdutoes.Find(detail.ProdutoId);
            if (product != null)
            {
                details.Add(new OrderDetailldTmp
                {
                    Descricao = product.Descricao,
                    Price = product.Precoprazo,
                    ProdutoId = product.ProdutoId,
                    Quantity = detail.Quantity,
                    Desconto = detail.Desconto,

                });
            }
        }

        var newOrderView = new NewOrderView
        {
            Details = details,
            IdCliente = orderRequest.IdCliente,
            Date = orderRequest.Date,
            CityId = orderRequest.CityId,
            FormaPagamentoId = orderRequest.FormaPagamentoId,
            FornecedorId = orderRequest.FornecedorId,
            DataEntrega = orderRequest.DataEntrega,
            HoraIncial = orderRequest.HoraIncial,
            Remarks = orderRequest.Remarks
        };



        var response = MovementsHelper.NewOrder(newOrderView);

        if (response.Succeeded)
        {
            return Ok("Venda Salva!!");
        }

        return BadRequest(response.Message);
    }