C# – WPF DataGrid binding problem

bindingcwpfxaml

Lets say we have the following code in XAML (the datagrid is bound to an ObservableCollection and the column to a property of the ObservableCollection:

<WpfToolkit:DataGrid
        ItemsSource="{Binding Path=Collection}"
        HorizontalScrollBarVisibility="Hidden" SelectionMode="Extended"
        CanUserAddRows="False" CanUserDeleteRows="False"
        CanUserResizeRows="False" CanUserSortColumns="False"
        AutoGenerateColumns="False"
        RowHeaderWidth="17" RowHeight="25">
        <WpfToolkit:DataGrid.Columns>

            <WpfToolkit:DataGridTextColumn
                Header="Names" Width="2*"
                Binding="{Binding Path=Name}"/>

        </WpfToolkit:DataGrid.Columns>
</WpfToolkit:DataGrid>

How can you create a new column programmatically in C# with the binding set to a certain PropertyPath (in my case a property of an ObservableCollection)?

This is what I have right now:

Binding items = new Binding();
PropertyPath path = new PropertyPath("Name");
items.Path = path;



MyDataGrid.Columns.Add(new DataGridTextColumn()
{
   Header = "Names",
   Width =  275,
   Binding = items
});

I am pretty sure that the problem is in the PropertyPath but I do not know what I must write in it…

Thank you for any help!

Best Answer

I have almost the exact same code as you, I just create the binding in a slightly different way:

void Add(ColumnViewModel columnViewModel)
{
    var column = new DataGridTextColumn
    {
        Header = columnViewModel.Name,
        Binding = new Binding("[" + columnViewModel.Name + "]")
    };
    dataGrid.Columns.Add(column);
}

Related Solutions

C# – Binding a WPF ComboBox to a custom list

You set the DisplayMemberPath and the SelectedValuePath to "Name", so I assume that you have a class PhoneBookEntry with a public property Name.

Have you set the DataContext to your ConnectionViewModel object?

I copied you code and made some minor modifications, and it seems to work fine. I can set the viewmodels PhoneBookEnty property and the selected item in the combobox changes, and I can change the selected item in the combobox and the view models PhoneBookEntry property is set correctly.

Here is my XAML content:

<Window x:Class="WpfApplication6.Window1"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Window1" Height="300" Width="300">
<Grid>
    <StackPanel>
        <Button Click="Button_Click">asdf</Button>
        <ComboBox ItemsSource="{Binding Path=PhonebookEntries}"
                  DisplayMemberPath="Name"
                  SelectedValuePath="Name"
                  SelectedValue="{Binding Path=PhonebookEntry}" />
    </StackPanel>
</Grid>
</Window>

And here is my code-behind:

namespace WpfApplication6
{

    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
            ConnectionViewModel vm = new ConnectionViewModel();
            DataContext = vm;
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            ((ConnectionViewModel)DataContext).PhonebookEntry = "test";
        }
    }

    public class PhoneBookEntry
    {
        public string Name { get; set; }

        public PhoneBookEntry(string name)
        {
            Name = name;
        }

        public override string ToString()
        {
            return Name;
        }
    }

    public class ConnectionViewModel : INotifyPropertyChanged
    {
        public ConnectionViewModel()
        {
            IList<PhoneBookEntry> list = new List<PhoneBookEntry>();
            list.Add(new PhoneBookEntry("test"));
            list.Add(new PhoneBookEntry("test2"));
            _phonebookEntries = new CollectionView(list);
        }

        private readonly CollectionView _phonebookEntries;
        private string _phonebookEntry;

        public CollectionView PhonebookEntries
        {
            get { return _phonebookEntries; }
        }

        public string PhonebookEntry
        {
            get { return _phonebookEntry; }
            set
            {
                if (_phonebookEntry == value) return;
                _phonebookEntry = value;
                OnPropertyChanged("PhonebookEntry");
            }
        }

        private void OnPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
        public event PropertyChangedEventHandler PropertyChanged;
    }
}

Edit: Geoffs second example does not seem to work, which seems a bit odd to me. If I change the PhonebookEntries property on the ConnectionViewModel to be of type ReadOnlyCollection, the TwoWay binding of the SelectedValue property on the combobox works fine.

Maybe there is an issue with the CollectionView? I noticed a warning in the output console:

System.Windows.Data Warning: 50 : Using CollectionView directly is not fully supported. The basic features work, although with some inefficiencies, but advanced features may encounter known bugs. Consider using a derived class to avoid these problems.

Edit2 (.NET 4.5): The content of the DropDownList can be based on ToString() and not of DisplayMemberPath, while DisplayMemberPath specifies the member for the selected and displayed item only.

C# – WPF DataGrid: DataGridComboxBox ItemsSource Binding to a Collection of Collections

Firstly, this should be easy... secondly, why are you building (and binding) columns in C#? Eek.

XAML (I'm using a regular grid because I'm lazy):

<ListView Name="MyListView">
    <ListView.View>
        <GridView>

            <GridView.Columns>

                <GridViewColumn DisplayMemberBinding="{Binding Operation}" />

                <GridViewColumn>
                    <GridViewColumn.CellTemplate>
                        <DataTemplate>
                            <ComboBox ItemsSource="{Binding Choices}" />
                        </DataTemplate>
                    </GridViewColumn.CellTemplate>
                </GridViewColumn>

            </GridView.Columns>

        </GridView>
    </ListView.View>
</ListView>

C#:

void Window1_Loaded(object sender, RoutedEventArgs e)
{
    var dahList = new List<StatsOperation>();

    dahList.Add(new StatsOperation
    {
        Operation = "Op A",
        Choices = new string[] { "One", "Two", "Three" },
    });

    dahList.Add(new StatsOperation
    {
        Operation = "Op B",
        Choices = new string[] { "4", "5", "6" },
    });

    this.MyListView.ItemsSource = dahList;
}

The Results:

WPF grid with dynamic combo box choices http://www.singingeels.com/Articles/Articles/UserImage.aspx?ImageID=b1e3f880-c278-4d2b-bcc2-8ad390591200

Best Answer

Related Solutions

C# – Binding a WPF ComboBox to a custom list

C# – WPF DataGrid: DataGridComboxBox ItemsSource Binding to a Collection of Collections

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