How to change the order of data from properties displayed in a WPF DataGrid from a base class and derived class?

Question

I would like to display data (Properties) from base class followed by data from a derived class in the columns of a DataGrid. Data displays OK, but data from Derived class is displayed first followed by the data from the derived class. How can I change the order of data so that Data first comes from base class and then from derived class.

    abstract class BaseNumbers
    {
        public int Count { get; set; }
        public double B1 { get; set; }
        public double B2 { get; set; }
        public double B3 { get; set; }


        protected BaseNumbers (int c, double b1, double b2, double b3)
        {
            Count = c;
            B1 = b1;
            B2 = b2;
            B3 = b3;
        } // end ctor

        public override string ToString() => $"{B1:F},{B2:F},{B3:F}";

   class DerivedNumbers : BaseNumbers
    {
        public double D1 { get; set; }
        public double D2 { get; set; }
        public double D3 { get; set; }

        public DerivedNumbers(int cnt, double b1, double b2, double b3,
            double d1, double d2, double d3)
            : base(cnt, b1, b2, b3)
        {
            D1 = d1;
            D2 = d2;
            D3 = d3;
        } // end ctor

        public override string ToString() => base.ToString() + $",{D1:F},{D2:F},{D3:F}";
    }

using System.Collections.Generic;
using System.Windows;

namespace OOPGridIssue
{
    /// 
    /// Interaction logic for MainWindow.xaml
    /// 
    public partial class MainWindow : Window
    {
        readonly List numbers = new List()
        {
            new DerivedNumbers(1,1.0, 2.22, 3, 4.0, 5.555, 6),
            new DerivedNumbers(2,1.0, 2.22, 3, 4.0, 5.555, 6),
            new DerivedNumbers(3,1.0, 2.22, 3, 4.0, 5.555, 6)
        };
        public MainWindow()
        {
            InitializeComponent();
        }

        private void ButtonClearNumbers_Click(object sender, RoutedEventArgs e)
        {
            dg_Numbers.ItemsSource = null;
            dg_Numbers.Items.Refresh();

        }

        private void ButtonLoadNumbers_Click(object sender, RoutedEventArgs e)
        {
            dg_Numbers.ItemsSource = numbers;
            dg_Numbers.Items.Refresh();
        }
    }
}

Seb · Accepted Answer

I can propose you two solutions:

Solution #1 Make use of the DataGrid's AutoGenerated event

Firstly, we create an interface

public interface IDerivedNumbers
{
    int Count { get; set; }
    double B1 { get; set; }
    double B2 { get; set; }
    double B3 { get; set; }

    double D1 { get; set; }
    double D2 { get; set; }
    double D3 { get; set; }

    string ToString();
}

Which we will apply it to the DerivedNumbers class

class DerivedNumbers : BaseNumbers, IDerivedNumbers
{
    ...
}

Now, lets add our event to the DataGrid

..and code behind

private void dg_Numbers_AutoGeneratedColumns(object sender, EventArgs e)
{
    var names = typeof(IDerivedNumbers).GetProperties()
                                       .Select ( (x, index) => new { name = x.Name, index } );

    if ( sender is DataGrid datagrid )
    {
        foreach ( var column in datagrid.Columns )
        {
            column.DisplayIndex = names.Single ( x => x.name == (string)column.Header ).index;
        }
    }
}

Solution #2 Hide your numbers classes behind an interface. The trick is your concrete classes must not be visible by the Datagrid, which means you'll need to move them in a separate assembly.

Firstly, lets move BaseNumbers & DerivedNumbers in another assembly and keep them internal.

Then Create a new public interface in that assembly

public interface IDerivedNumbers
{
    int Count { get; set; }
    double B1 { get; set; }
    double B2 { get; set; }
    double B3 { get; set; }

    double D1 { get; set; }
    double D2 { get; set; }
    double D3 { get; set; }

    string ToString();
}

Apply it to the DerivedNumbers class

class DerivedNumbers : BaseNumbers, IDerivedNumbers
{
    ...
}

Next, we need to create a public factory

public static class NumbersFactory
{

    public static IDerivedNumbers Create ( int cnt, 
                                           double b1, 
                                           double b2, 
                                           double b3,
                                           double d1, 
                                           double d2, 
                                           double d3 )
    {
        new DerivedNumbers(cnt, b1, b2, b3, d1, d2, d3);
    }
}

Finally link your new assembly and use the factory to create the numbers

public partial class MainWindow : Window
{
    readonly List numbers = new List()
    {
        NumbersFactory.Create(1,1.0, 2.22, 3, 4.0, 5.555, 6),
        NumbersFactory.Create(2,1.0, 2.22, 3, 4.0, 5.555, 6),
        NumbersFactory.Create(3,1.0, 2.22, 3, 4.0, 5.555, 6)
    };

    ....
}

Now the Datagrid will only pick up the interface and auto generate the columns in the right order.

Both methods will generate this result:

PS. Thank you for providing a working example by the way !

How to change the order of data from properties displayed in a WPF DataGrid from a base class and derived class?

Answers (1)

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