如何为用作 DataGrid 的项源的项的集合属性中的每个项生成和绑定列

Question

我的数据网格的项源是一组对象，如：

Public Property Quarter As Integer
Public Property MyColumns() As New List(Of MyColumn)

现在我想要一个网格绑定，使我得到的网格看起来像

--四分之一--第1列--第2列--第3列。。。。第X列

数据源中的所有项都将具有相同的MyColumns。

有没有一种方法可以将集合绑定到网格列？

Answer 1

这是解决方案。它不是最漂亮或最简单的，但它是相当可配置的。它主要基于后WPF:Dictionary<int，列表<字符串>gt；在DataGrid中，它只是变成了一个更通用的版本，带有一些表达式和反射。

无论用作ItemsSource的项在各自的集合属性中包含的项数量是相同还是不同，它都将起作用。

---

任意长度

以下是所需的组件：

using System.Reflection;
using Expressions = System.Linq.Expressions;
// See - https://stackoverflow.com/questions/2132791/reflecting-over-all-properties-of-an-interface-including-inherited-ones
public static class ReflectionExtensions
{
    public static PropertyInfo GetInterfaceProperty(this Type type, String propName, Type returnType)
    {
        if (propName == null)
            throw new ArgumentNullException("propName");
        if (returnType == null)
            throw new ArgumentNullException("propType");
        return type.GetInterfaces()
            .Select(parentInterface =>
                parentInterface.GetProperty(propName, returnType))
            .Where(prop =>
                prop != null)
            .Single();
    }
}
public static class CollectionPropertyDataGridBindingHelper
{
    public static void RemoveAutoGeneratedColumns(this DataGrid dataGrid, String propertyName)
    {
        if (dataGrid == null)
            throw new ArgumentNullException("dataGrid");
        if (propertyName == null)
            throw new ArgumentNullException("propertyName");
        var autogeneratedColumns = dataGrid
            .Columns
            .OfType<DataGridBoundColumn>()
            .Where(col =>
                (col.Binding as Binding).Path.Path.Equals(propertyName));
        foreach (var autoColumn in autogeneratedColumns)
        {
            dataGrid.Columns.Remove(autoColumn);
        }
    }

    public static void RegenerateColumns<TItem, TPropertyCollectionItem>(
        this DataGrid dataGrid,
        Expressions.Expression<Func<TItem, IEnumerable<TPropertyCollectionItem>>> propertyExpression, 
        IEnumerable<TItem> items)
    {
        RegenerateColumns<TItem, TPropertyCollectionItem>(dataGrid,
            propertyExpression,
            items,
            (index) =>
                String.Format("Column - {0}", index));
    }

    public static void RegenerateColumns<TItem, TPropertyCollectionItem>(
        this DataGrid dataGrid, 
        Expressions.Expression<Func<TItem, IEnumerable<TPropertyCollectionItem>>> collectionPropertyExpression, 
        IEnumerable<TItem> items, 
        Func<Int32, String> formatHeader)
    {
        if (dataGrid == null)
            throw new ArgumentNullException("dataGrid");
        if (collectionPropertyExpression == null)
            throw new ArgumentNullException("propertyExpression");
        if (items == null)
            throw new ArgumentNullException("items");
        if (formatHeader == null)
            throw new ArgumentNullException("formatHeader");
        var collectionPropInfo = GetCollectionPropertyInfoFor<TItem, TPropertyCollectionItem>(collectionPropertyExpression);
        var propertyName = collectionPropInfo.Name;
        var getCount = GetCountGetter<TItem, TPropertyCollectionItem>(
            collectionPropertyExpression.Compile(),
            collectionPropInfo);
        // Remove old autocolumns
        dataGrid.RemoveAutoGeneratedColumns(propertyName);
        Int32 columnsRequired = items.Select(item => getCount(item)).Max();
        // Create new columns
        GenerateColumns(dataGrid,
            formatHeader,
            propertyName,
            columnsRequired);
    }    
    private static void GenerateColumns(DataGrid dataGrid,
        Func<Int32, String> formatHeader,
        String propertyName,
        Int32 columnsRequired)
    {
        for (int columnNumber = 0; columnNumber < columnsRequired; columnNumber++)
        {
            DataGridTextColumn column = new DataGridTextColumn()
            {
                Header = formatHeader(columnNumber),
                Binding = new Binding(String.Format("{0}[{1}]",
                    propertyName,
                    columnNumber))
            };
            dataGrid.Columns.Add(column);
        }
    }

    private static Func<TItem, Int32> GetCountGetter<TItem, TPropertyCollectionItem>(
        Func<TItem, IEnumerable<TPropertyCollectionItem>> getCollection,
        PropertyInfo propInfo)
    {
        if (getCollection == null)
            throw new ArgumentNullException("getCollection");
        if (propInfo == null)
            throw new ArgumentNullException("propInfo");
        var collectionType = propInfo.PropertyType;
        
        var countGetter = collectionType.GetInterfaceProperty("Count",
            typeof(Int32));
        if (countGetter != null)
        {
            return (item) =>
                (Int32)countGetter.GetMethod.Invoke(getCollection(item), null);
        }
        throw new NotImplementedException("Not implemented: For simple IEnumerables the use of Enumerable.Count() method shall be considered.");
    }

    private static PropertyInfo GetCollectionPropertyInfoFor<TItem, TPropertyCollectionItem>(
        Expressions.Expression<Func<TItem, 
        IEnumerable<TPropertyCollectionItem>>> propertyExpression)
    {
        if (propertyExpression == null)
            throw new ArgumentNullException("propertyExpression");
        
        var memberExp = propertyExpression.Body as Expressions.MemberExpression;
        if (memberExp == null)
            throw new ArgumentNullException("propertyExpression");
        var propInfo = memberExp.Member as PropertyInfo;
        if (propInfo == null)
            throw new ArgumentNullException("propertyExpression");
        if (!propInfo.DeclaringType.IsAssignableFrom(typeof(TItem)))
            throw new ArgumentException("propertyExpression");
        
        return propInfo;
    }
}

---

这是XAML：

    <DataGrid ItemsSource="{Binding Items}" AutoGenerateColumns="False" Name="dataGrid">
        <DataGrid.Columns>
            <DataGridTextColumn Header="Quarter" Binding="{Binding Quarter}"/>
        </DataGrid.Columns>
    </DataGrid>

这是背后的代码：

using Expressions = System.Linq.Expressions
public class Item
{
    public Item(Int32 quarter, Int32 repeatColumns)
    {
        this.Quarter = quarter;
        this.MyColumns = Enumerable
            .Range(1, repeatColumns)
            .ToList();
    }
    public Int32 Quarter
    {
        get; set;
    }
    public IList<Int32> MyColumns
    {
        get; set;
    }
}

/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        this.Items = GetOriginalItems();
        this.DataContext = this;
        this.ReinitializeColumns();
    }
    private void ReinitializeColumns()
    {
        Expressions.Expression<Func<Item, IEnumerable<Int32>>> exp = 
            obj => 
                obj.MyColumns;
        this.dataGrid.RegenerateColumns(exp,
            this.Items);
    }
    public IEnumerable<Item> Items
    {
        get;
        private set;
    }
    public IEnumerable<Item> GetOriginalItems()
    {
        return new Item[] 
        {
            new Item(1, 3),
            new Item(2, 2),
            new Item(3, 5),
            new Item(4, 2),
        };
    }
}

---

设置长度

以下是将创建指定数量的列的代码（您可以将其放在某个独立类中，因为它是完全自包含的，或者放在具有任意长度方法的同一类中（在这种情况下，请不要忘记删除重复的生成方法）。它简单一点，直接适合您的需求：

    public static void RegenerateColumns<TItem, TPropertyCollectionItem>(
       this DataGrid dataGrid,
       String propertyName,
       Int32 columnsRequired)
    {
        dataGrid.RegenerateColumns<TItem, TPropertyCollectionItem>(propertyName,
            columnsRequired,
            index => String.Format("Column - {0}",
                index));
    }

    public static void RegenerateColumns<TItem, TPropertyCollectionItem>(
        this DataGrid dataGrid,
        String propertyName,
        Int32 columnsRequired,
        Func<Int32, String> formatHeader)
    {
        if (dataGrid == null)
            throw new ArgumentNullException("dataGrid");
        if (propertyName == null)
            throw new ArgumentNullException("propertyName");
        if (columnsRequired < 0)
            throw new ArgumentOutOfRangeException("columnsRequired");
        if (formatHeader == null)
            throw new ArgumentNullException("formatHeader");
        // Remove old autocolumns
        dataGrid.RemoveAutoGeneratedColumns(propertyName);
        
        GenerateColumns(dataGrid,
            formatHeader,
            propertyName,
            columnsRequired);
    }

    private static void GenerateColumns(DataGrid dataGrid,
        Func<Int32, String> formatHeader,
        String propertyName,
        Int32 columnsRequired)
    {
        for (int columnNumber = 0; columnNumber < columnsRequired; columnNumber++)
        {
            DataGridTextColumn column = new DataGridTextColumn()
            {
                Header = formatHeader(columnNumber),
                Binding = new Binding(String.Format("{0}[{1}]",
                    propertyName,
                    columnNumber))
            };
            dataGrid.Columns.Add(column);
        }
    }

正是背后的代码使用了它：

    public MainWindow()
    {
        InitializeComponent();
        this.Items = GetOriginalItems();
        this.DataContext = this;
        this.ReinitializeColumns(2);
    }
    private void ReinitializeColumns(Int32 columnsCount)
    {
        this.dataGrid.RegenerateColumns<Item, Int32>("MyColumns",
            columnsCount);
    }

Answer 2

Eugene向我提供了关于动力学和expandoObject的见解，这就是我为解决当前问题而实现的。

这是我的解决方案--

我们有一个来自模型的集合，它的结构相当坚硬。因此，为了将它绑定到UI网格，我们需要另一个对象以视觉上不同的方式映射当前列表。

--使用Expando对象--

您可以创建ExpandoObjects的集合，并将其动态特性映射到集合的特性。

Dim pivotItems As Object = New ExpandoObject()
    ' set properties for object'
     pivotItems.Quarter = developmentQuarters.Key
     pivotItems.Name = developmentQuarters.Key.Name
     ' since expando obj is a dictionary for prop name and its value we can set property names dynamically like this'
     For Each developmentModel As DevelopmentModel In developmentModels
         Dim pivotAsDict As IDictionary(Of String, Object) = pivotItems
         pivotAsDict.Add(developmentModel.BusinessGroupName + " " + developmentModel.Currency.Code, developmentModel.DevelopmentPercentage)
      Next
      ReModelledItems.Add(pivotItems)

因此，现在我们将一个嵌套对象展开为一个简单的集合，它具有基于初始集合中的值生成的动态列/属性。

我们现在可以简单地绑定这个ExpandoObjects 集合