Is it possible to get dynamic columns on wpf datagrid in mvvm pattern?

Question

Im developing a product in wpf (mvvm pattern). I have a scenario in which i have spent more than a week for no good result. Pls help me if you can... Here is the scenario, a

Answer 1

I would like to extend the previous example (answer) the ability to subscribe and unsubscribe on event CollectionChanged.

Behavior (add reference on System.Windows.Interactivity):

 public class ColumnsBindingBehaviour : Behavior<DataGrid>
{
    public ObservableCollection<DataGridColumn> Columns
    {
        get { return (ObservableCollection<DataGridColumn>) base.GetValue(ColumnsProperty); }
        set { base.SetValue(ColumnsProperty, value); }
    }

    public static readonly DependencyProperty ColumnsProperty = DependencyProperty.Register("Columns",
        typeof(ObservableCollection<DataGridColumn>), typeof(ColumnsBindingBehaviour),
            new PropertyMetadata(OnDataGridColumnsPropertyChanged));

    private static void OnDataGridColumnsPropertyChanged(DependencyObject source, DependencyPropertyChangedEventArgs e)
    {
        var context = source as ColumnsBindingBehaviour;

        var oldItems = e.OldValue as ObservableCollection<DataGridColumn>;

        if (oldItems != null)
        {
            foreach (var one in oldItems)
                context._datagridColumns.Remove(one);

            oldItems.CollectionChanged -= context.collectionChanged;
        }

        var newItems = e.NewValue as ObservableCollection<DataGridColumn>;

        if (newItems != null)
        {
            foreach (var one in newItems)
                context._datagridColumns.Add(one);

            newItems.CollectionChanged += context.collectionChanged;
        }
    }

    private ObservableCollection<DataGridColumn> _datagridColumns;

    protected override void OnAttached()
    {
        base.OnAttached();

        this._datagridColumns = AssociatedObject.Columns;
    }


    private void collectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        switch (e.Action)
        {
            case NotifyCollectionChangedAction.Add:
                if (e.NewItems != null)
                    foreach (DataGridColumn one in e.NewItems)
                        _datagridColumns.Add(one);
                break;

            case NotifyCollectionChangedAction.Remove:
                if (e.OldItems != null)
                    foreach (DataGridColumn one in e.OldItems)
                        _datagridColumns.Remove(one);
                break;

            case NotifyCollectionChangedAction.Move:
                _datagridColumns.Move(e.OldStartingIndex, e.NewStartingIndex);
                break;

            case NotifyCollectionChangedAction.Reset:
                _datagridColumns.Clear();
                if (e.NewItems != null)
                    foreach (DataGridColumn one in e.NewItems)
                        _datagridColumns.Add(one);
                break;
        }
    }
}

View:

<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

    xmlns:loc="clr-namespace:WpfApplication1"
    xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
    Title="MainWindow" Height="350" Width="525">
<Grid>
    <DataGrid x:Name="_dataGrid">
        <DataGrid.Columns>
            <DataGridTextColumn Header="Test" />
        </DataGrid.Columns>
        <i:Interaction.Behaviors>
            <loc:ColumnsBindingBehaviour Columns="{Binding DataGridColumns}"/>        
        </i:Interaction.Behaviors>
    </DataGrid>
</Grid>

ViewModel:

     private ObservableCollection<DataGridColumn> _dataGridColumns;
     public ObservableCollection<DataGridColumn> DataGridColumns
     {
         get
         {
             if (_dataGridColumns == null)
                 _dataGridColumns = new ObservableCollection<DataGridColumn>()
                 {
                     new DataGridTextColumn()
                     {
                         Header = "Column1"
                     }
                 };

             return _dataGridColumns;
         }
         set
         {
             _dataGridColumns = value;
             OnPropertyChanged("DataGridColumns");
         }
     }

Answer 2

Thanks for your effort guy's... finally i have found the solution....

here its..(full wpf mvvm)

In my command file:

public class DataGridColumnsBehavior
    {
        public static readonly DependencyProperty BindableColumnsProperty =
            DependencyProperty.RegisterAttached("BindableColumns",
                                                typeof(ObservableCollection<DataGridColumn>),
                                                typeof(DataGridColumnsBehavior),
                                                new UIPropertyMetadata(null, BindableColumnsPropertyChanged));
        private static void BindableColumnsPropertyChanged(DependencyObject source, DependencyPropertyChangedEventArgs e)
        {
            DataGrid dataGrid = source as DataGrid;
            ObservableCollection<DataGridColumn> columns = e.NewValue as ObservableCollection<DataGridColumn>;
            dataGrid.Columns.Clear();
            if (columns == null)
            {
                return;
            }
            foreach (DataGridColumn column in columns)
            {
                dataGrid.Columns.Add(column);
            }
            columns.CollectionChanged += (sender, e2) =>
            {
                NotifyCollectionChangedEventArgs ne = e2 as NotifyCollectionChangedEventArgs;
                if (ne.Action == NotifyCollectionChangedAction.Reset)
                {
                    dataGrid.Columns.Clear();
                    if (ne.NewItems != null)
                    {
                        foreach (DataGridColumn column in ne.NewItems)
                        {
                            dataGrid.Columns.Add(column);
                        }
                    }
                }
                else if (ne.Action == NotifyCollectionChangedAction.Add)
                {
                    if (ne.NewItems != null)
                    {
                        foreach (DataGridColumn column in ne.NewItems)
                        {
                            dataGrid.Columns.Add(column);
                        }
                    }
                }
                else if (ne.Action == NotifyCollectionChangedAction.Move)
                {
                    dataGrid.Columns.Move(ne.OldStartingIndex, ne.NewStartingIndex);
                }
                else if (ne.Action == NotifyCollectionChangedAction.Remove)
                {
                    if (ne.OldItems != null)
                    {
                        foreach (DataGridColumn column in ne.OldItems)
                        {
                            dataGrid.Columns.Remove(column);
                        }
                    }
                }
                else if (ne.Action == NotifyCollectionChangedAction.Replace)
                {
                    dataGrid.Columns[ne.NewStartingIndex] = ne.NewItems[0] as DataGridColumn;
                }
            };
        }
        public static void SetBindableColumns(DependencyObject element, ObservableCollection<DataGridColumn> value)
        {
            element.SetValue(BindableColumnsProperty, value);
        }
        public static ObservableCollection<DataGridColumn> GetBindableColumns(DependencyObject element)
        {
            return (ObservableCollection<DataGridColumn>)element.GetValue(BindableColumnsProperty);
        }
    }

in my xaml:

<my:DataGrid AutoGenerateColumns="False" Margin="357,121.723,82,41" Name="dataGrid3" ItemsSource="{Binding Path=Datatable}" c:DataGridColumnsBehavior.BindableColumns="{Binding ColumnCollection}" />

and finaly in my viewmodel:

private ObservableCollection<DataGridColumn> _columnCollection = new ObservableCollection<DataGridColumn>();
        public ObservableCollection<DataGridColumn> ColumnCollection
        {
            get
            {
                return this._columnCollection;
            }
            set
            {
                _columnCollection = value;
                base.OnPropertyChanged("ColumnCollection");
                //Error
                //base.OnPropertyChanged<ObservableCollection<DataGridColumn>>(() => this.ColumnCollection);
            }
        }
        private DataTable _datatable = new DataTable();
        public DataTable Datatable
        {
            get
            {
                return _datatable;
            }
            set
            {
                if (_datatable != value)
                {
                    _datatable = value;
                }
                base.OnPropertyChanged("Datatable");
            }
        }

and in my constructor:

public MainViewModel()
        {
Datatable.Columns.Add("Name",typeof(string));
            Datatable.Columns.Add("Color", typeof(string));
            Datatable.Columns.Add("Phone", typeof(string));
            Datatable.Rows.Add("Vinoth", "#00FF00", "456345654");
            Datatable.Rows.Add("lkjasdgl", "Blue", "45654");
            Datatable.Rows.Add("Vinoth", "#FF0000", "456456");
System.Windows.Data.Binding bindings = new System.Windows.Data.Binding("Name");
            System.Windows.Data.Binding bindings1 = new System.Windows.Data.Binding("Phone");
            System.Windows.Data.Binding bindings2 = new System.Windows.Data.Binding("Color");
            DataGridTextColumn s = new DataGridTextColumn();
            s.Header = "Name";
            s.Binding = bindings;
            DataGridTextColumn s1 = new DataGridTextColumn();
            s1.Header = "Phone";
            s1.Binding = bindings1;
            DataGridTextColumn s2 = new DataGridTextColumn();
            s2.Header = "Color";
            s2.Binding = bindings2;

            FrameworkElementFactory textblock = new FrameworkElementFactory(typeof(TextBlock));
            textblock.Name = "text";
            System.Windows.Data.Binding prodID = new System.Windows.Data.Binding("Name");
            System.Windows.Data.Binding color = new System.Windows.Data.Binding("Color");
            textblock.SetBinding(TextBlock.TextProperty, prodID);
            textblock.SetValue(TextBlock.TextWrappingProperty, TextWrapping.Wrap);
            //textblock.SetValue(TextBlock.BackgroundProperty, color);
            textblock.SetValue(TextBlock.NameProperty, "textblock");
            //FrameworkElementFactory border = new FrameworkElementFactory(typeof(Border));
            //border.SetValue(Border.NameProperty, "border");
            //border.AppendChild(textblock);
            DataTrigger t = new DataTrigger();
            t.Binding = new System.Windows.Data.Binding { Path = new PropertyPath("Name"), Converter = new EnableConverter(), ConverterParameter ="Phone" };
            t.Value = 1;
            t.Setters.Add(new Setter(TextBlock.BackgroundProperty, Brushes.LightGreen, textblock.Name));
            t.Setters.Add(new Setter(TextBlock.ToolTipProperty, bindings, textblock.Name));
            DataTrigger t1 = new DataTrigger();
            t1.Binding = new System.Windows.Data.Binding { Path = new PropertyPath("Name"), Converter = new EnableConverter(), ConverterParameter = "Phone" };
            t1.Value = 2;
            t1.Setters.Add(new Setter(TextBlock.BackgroundProperty, Brushes.LightYellow, textblock.Name));
            t1.Setters.Add(new Setter(TextBlock.ToolTipProperty, bindings, textblock.Name));

            DataTemplate d = new DataTemplate();
            d.VisualTree = textblock;
            d.Triggers.Add(t);
            d.Triggers.Add(t1);

            DataGridTemplateColumn s3 = new DataGridTemplateColumn();
            s3.Header = "Name 1";
            s3.CellTemplate = d;
            s3.Width = 140;

            ColumnCollection.Add(s); 
            ColumnCollection.Add(s1);
            ColumnCollection.Add(s2);
            ColumnCollection.Add(s3);
    }