Question

Hello I have an observablecollection that allows user to add rows using an “Add” button. And the user can group the items with the same name within the same header. Here is the code:

The code behind data:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel;
using System.Collections.ObjectModel;
namespace WpfDataGridWithDataTable
{
    public class Article
    {
        public  Article ()
        {

        }
        private int  _modelNumber;
        public int ModelNumber
        {
            get { return _modelNumber; }
            set { _modelNumber = value; OnPropertyChanged("ModelNumber"); }
        }

        private string _modelName;
        public string ModelName
        {
            get { return _modelName; }
            set { _modelName = value; OnPropertyChanged("ModelName"); }
        }

        private decimal  _unitCost;
        public decimal UnitCost
        {
            get { return _unitCost; }
            set { _unitCost = value; OnPropertyChanged("UnitCost"); }
        }

        private string  _description ;
        public string Description
        {
            get { return _description; }
            set { _description = value; OnPropertyChanged("Description"); }
        }


        #region INotifyPropertyChanged Membres

        public event PropertyChangedEventHandler PropertyChanged;
        private void OnPropertyChanged(string propName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propName));
            }
        }
        #endregion
    }
    public class ListArticles : ObservableCollection<Article > 
    {
        public Article a;
        public ListArticles()
        {

                a = new Article();
                this.Add(a);

        }

    }

}

XAML code:

<Window x:Class="WpfDataGridWithDataTable.Window1"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:WpfDataGridWithDataTable"
        Title="Window1" Height="300" Width="300">
    <Grid
        Name="gridPanel">
        <Grid.RowDefinitions>
            <RowDefinition Height="*"></RowDefinition>
            <RowDefinition Height="40"></RowDefinition>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"></ColumnDefinition>
            <ColumnDefinition Width="*"></ColumnDefinition>
        </Grid.ColumnDefinitions>
        <DataGrid 
            Grid.Column="0"
            Name="dataGrid1"  
            AutoGenerateColumns="True"  
            CanUserAddRows="True" 
            CanUserDeleteRows="True"
            CanUserResizeColumns="True"
            IsSynchronizedWithCurrentItem="True"
            ItemsSource="{Binding}"/>
        <ListBox 
            Grid.Column="1"
            Name="listBox1" 
            IsSynchronizedWithCurrentItem="True"
            ItemsSource="{Binding}">
            <ListBox.ItemTemplate>
                <DataTemplate DataType="{x:Type local:Article}">
                    <StackPanel    
                        Orientation="Horizontal">
                        <TextBlock 
                            Width="100"
                            Margin="10"  
                            Background="DarkBlue"
                            Foreground="White"
                            FontSize="14"
                            Text="{Binding ModelNumber}"/>
                        <TextBlock 
                            Width="100"
                            Margin="10" 
                            Background="DarkBlue"
                            Foreground="White"
                            FontSize="14"
                            Text="{Binding ModelName}"/>
                    </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
            <Button 
                Grid.Row="1"
                Grid.Column="0"
                HorizontalAlignment="Left"
                Width="100"
                Name="btnAdd"
                Content="Add Item"
                Click="btnAdd_Click">
            </Button>
            <Button
                Grid.Row="1"
                Grid.Column="1"
                HorizontalAlignment="Right"
                Width="100"
                Name="btnDelete"
                Content="Delete Item"
                Click="btnDelete_Click" >
            </Button>
    </Grid>
</Window>

The code behind the form:

namespace WpfDataGridWithDataTable
{

    public partial class Window1 : Window
    {
        private ListArticles myList;
        public Window1()
        {
            InitializeComponent();
            myList = new ListArticles();


            this.DataContext = myList;

        }

        private void btnAdd_Click(object sender, RoutedEventArgs e)
        {
            myList.Add(new Article());
        }

        private void btnDelete_Click(object sender, RoutedEventArgs e)
        {
            myList.Remove(this.dataGrid1.SelectedItem as Article);
        }

    }
}

I want to add a column called “Quantity”, which stores the quantity of each article added to the group. My question is this: How can I obtain the sum of quantities of each group?

Answer 1

Using Linq could solve this. (There might be an error in the code below, I didn’t pass it through a compiler)

var groupSumsQuery = from model in myList
                     group model by model.ModelName into modelGroup
                     select new 
                         {
                             Name = modelGroup.Key,
                             Sum = modelGroup.Sum(model=>model.UnitCost)
                         };

foreach(var group in groupSumsQuery)
{
    Console.WriteLine("Total price for all {0}: {1}", group.Name, group.Sum);
}