是否有可能在mvvm模式中获取wpf datagrid上的动态列？

Question

我正在开发wpf(mvvm模式)的产品.我有一个场景,我已经花了一个多星期没有好结果.如果可以,请帮助我......这是场景,根据用户的自定义(用户ll选择列),我必须在datagrid中显示一组数据.目前我正在将带有一组属性的ObservableCollection绑定到datagrid的itemsource.这限制了我固定的列大小.注意:列出了n个列名称供用户选择.如果通过"datagrid.columns.add()"轻松完成后面的代码.在这种情况下,任何人都可以帮助我.

我的xaml:

<my:DataGrid AutoGenerateColumns="False" Margin="357,121.723,82,41" Name="dataGrid3" c:DataGridExtension.Columns="{Binding ColumnCollection}" />

我的命令类:

public static class DataGridExtension
{
    public static ObservableCollection<DataGridColumn> GetColumns(DependencyObject obj)
    {
        return (ObservableCollection<DataGridColumn>)obj.GetValue(ColumnsProperty);
    }

    public static void SetColumns(DependencyObject obj, ObservableCollection<DataGridColumn> value)
    {
        obj.SetValue(ColumnsProperty, value);
    }

    public static readonly DependencyProperty ColumnsProperty = 
        DependencyProperty.RegisterAttached("Columns", typeof(ObservableCollection<DataGridColumn>),typeof(DataGridExtension),
         new UIPropertyMetadata (new ObservableCollection<DataGridColumn>(), OnDataGridColumnsPropertyChanged));

    private static void OnDataGridColumnsPropertyChanged(DependencyObject d,
           DependencyPropertyChangedEventArgs e)
    {
        if (d.GetType() == typeof(DataGrid))
        {
            DataGrid myGrid = d as DataGrid;

            ObservableCollection<DataGridColumn> Columns = (ObservableCollection<DataGridColumn>)e.NewValue;

            if (Columns != null)
            {
                myGrid.Columns.Clear();

                if (Columns != null && Columns.Count > 0)
                {
                    foreach (DataGridColumn dataGridColumn in Columns)
                    {
                        myGrid.Columns.Add(dataGridColumn);
                    }
                }


                Columns.CollectionChanged += delegate(object sender, NotifyCollectionChangedEventArgs args)
                {
                    if (args.NewItems != null)
                    {
                        //foreach (DataGridColumn column in args.NewItems.Cast<DataGridColumn>())
                        //{
                        //    myGrid.Columns.Add(column);
                        //}
                    }

                    if (args.OldItems != null)
                    {

                        //foreach (DataGridColumn column in args.OldItems.Cast<DataGridColumn>())
                        //{
                        //    myGrid.Columns.Remove(column);
                        //}
                    }
                };

            }
        }
    }
}

和我在viewmodel中的属性:

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);
    }
}

Answer 1

谢谢你的努力...最后我找到了解决方案....

这里.. ..(完整的wpf mvvm)

在我的命令文件中:

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);
        }
    }

在我的xaml中:

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

最后在我的viewmodel中:

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");
            }
        }

在我的构造函数中:

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);
    }