Populate aggregate class from datatable using a Dataset with LINQ C#

Question

I’m having trouble filling an aggregate class in C#. Is it possible using LINQ? Does anyone have any example of how to solve this problem using the return of a DataTable or DataSet?

public class OrderDetails
{
 . . .
}

public class Order
{
     private List<OrderDetails> details;
     public Person(OrderDetails pdetails)
     {
         this.details.Add(pdetails);
     }
     . . .
}

Answer 1

You will need to iterate on each Datatable result and group the information of each Order in a dictionary indexed by your Id, in order to be able to aggregate the Order Orderdetails in the same instances.

The first step is to make the details list public:

public class Order
{
     //Precisa ser público, já que a modelagem sugere que um Order 
     //pode ter mais de um OrderDetails. Precisaremos adicionar 
     //mais detalhes ao iterar nas linhas do DataSet.
     public List<OrderDetails> Details { get; set; } 

     //Mantive o OrderDetail sendo passado no construtor, já que o
     //modelo explicita que um Order deve possuir ao menos um OrderDetail
     public Order(OrderDetails detail) 
     {
         this.Details = new List<OrderDetails>();
         this.Details.Add(detail);
     }
}

Now we can iterate on the Dataset results and fill the class. I’ll assume some premises:

1) that the Order Id is a String. This premise is based only on the fact that it is easier to handle String in the example. Make the necessary conversions to your code.

2) that your Dataset has already been configured and a Datatable has already been created from it. If this premise is false, please search before on how to access DB data via Dataset:

private IEnumerable<Order> GetOrdersFromDataTable(DataTable ordersTable)
{
    var orderDict = new Dictionary<string, Order>(); 
    foreach (DataRow dr in ordersTable.Rows)
    {
        var orderDetail = new OrderDetail();
        //Todo: Preencher as propriedades do OrderDetail.
        string id = dr["Id"].ToString());
        if (!orderDict.ContainsKey(id))
        {
             var order = new Order(orderDetail);
             //Todo: Preencher as propriedades do Order.
             orderDict.Add(id, order);
        }
        else
             orderDict[id].Details.Add(orderDetail);
    }
    return orderDict.Values;
}

Editing: You asked if it was possible to fill the classes with Linq2sql, but I believe you meant Linq2sql, which is a tool for abstracting access to the data source, mapping tables into classes and allowing queries using Linq2sql. There is another library, however, called Entity Framework, more robust than the previous one, which came to replace it. If you are interested in learning more, I suggest researching EF and trying to implement an access to your bank using it. The documentation is extensive and there is material even in Portuguese. If you have any questions, ask another question on Stackoverflow, so it doesn’t become too wide.