How to view and edit data from multiple tables in a DataGrid with EF?

Question

I have 2 tables: Orders and Customers. Orders is related to Customers by the IdCustomer foreign key.

Problem: I want to show in the DataGrid the values from both tables and want to be able to edit the data belonging to the Orders table.

I managed to show and edit in the grid the Orders table, but how do I include the data from the Customers table?

this.grdData.ItemsSource = context.Orders;

private void btnSave_Click(object sender, RoutedEventArgs e)
{
    context.SaveChanges();
}

Answer 1

Usually, if you have a fk in your table, you'll have a relationship in your entity. If you don't have it, you should add it.

The best approach is to create a ViewModel class for what you want to show from both entities:

public class OrderViewModel {
    public string CustomerName{ get; set; }
    public decimal OrderTotal { get; set; }
    public DateTime Date { get; set; }
}

Then you need to execute a query that retrieves all the information:

var query = from o in dataContext.Orders
            select new ViewModel {
                                   CustomerName = o.Customer.Name,                                                            
                                   OrderTotal = o.Total,
                                   Date = o.Date
                                 };

and use it as the data source for the Grid.

If by any chances you don't have the relationship in your model, you can do a less straight forward query:

var query = from o in dataContext.Orders
            join c in dataContext.Customers on o.CustomerId equals c.Id
            select new ViewModel {
                                   CustomerName = c.Name,                                                            
                                   OrderTotal = o.Total,
                                   Date = o.Date
                                  };