c# - 如何为用作 DataGrid 的 ItemsSource 的项目的集合属性中的每个项目生成并绑定(bind)一列

Question

我的数据网格的项目源是对象的集合，例如:

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

现在我想要一个网格绑定(bind)，使我的结果网格看起来像

-- Quarter -- Column1 -- Column2 -- Column3 .... ColumnX

数据源中的所有项目都将具有相同的 MyColumns。

有没有办法可以将集合绑定(bind)到网格列？

Answer 1

这是解决方案。它不是最漂亮或最简单的，但它是非常可配置的。它主要基于帖子WPF: Dictionary<int, List<string>> in DataGrid的想法，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 的项目在各自的集合属性中包含相同或不同数量的项目，它都会起作用。

---

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>

这是隐藏代码:

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

这是将创建指定数量的列的代码(您可以将其放入某个独立类，因为它是完全独立的，或者放入具有任意长度方法的同一类(在这种情况下不要忘记删除重复的生成方法))。它更简单一些，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);
        }
    }

使用它的是隐藏代码:

    public MainWindow()
    {
        InitializeComponent();

        this.Items = GetOriginalItems();

        this.DataContext = this;

        this.ReinitializeColumns(2);
    }

    private void ReinitializeColumns(Int32 columnsCount)
    {
        this.dataGrid.RegenerateColumns<Item, Int32>("MyColumns",
            columnsCount);
    }