c# - DataGridView 使用 SortableBindingList

Question

我有一个返回 IList< T > 的函数，它是 DataGridView 的数据源。我了解到 DataGridView 不会对 IList 进行排序。我读了This stackoverflow Q&A并正在尝试实现 SortableBindingList。我一定是做错了什么，因为我的 DataGridView 是空的。我还尝试使用 TextBox 从 SortableBindingSource 访问一个元素，但什么也没有。

using Microsoft.SqlServer.Management.Controls;
public partial class Form1 : Form
{
    IBusinessLayer businessLayer;
    IList<Category> categories;
    SortableBindingList<Category> catSortable;

    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {

        businessLayer = new BusinessLayer();

        categories = businessLayer.GetAllCategories();
        catSortable = new SortableBindingList<Category>(categories);
        categoryBindingSource.DataSource = catSortable;
        categoryDataGridView.DataSource = categoryBindingSource;

        textBox1.Text = catSortable[0].CategoryName;

    }
}

我检查了 Microsoft.SqlServer.Management.Controls，这看起来正确吗？

namespace Microsoft.SqlServer.Management.Controls
{
    public class SortableBindingList<T> : BindingList<T>
    {
        public SortableBindingList();
        public SortableBindingList(IList<T> list);

        protected override bool IsSortedCore { get; }
        protected override ListSortDirection SortDirectionCore { get; }
        protected override PropertyDescriptor SortPropertyCore { get; }
        protected override bool SupportsSortingCore { get; }

        protected override void ApplySortCore(PropertyDescriptor prop, ListSortDirection direction);
        protected override void RemoveSortCore();
    }
}

我非常感谢帮助和帮助我学习。感谢大家!

Answer 1

试试这个 SortableBindingList:

public class SortableBindingList<T> : BindingList<T>
{
    private bool isSortedValue;
    ListSortDirection sortDirectionValue;
    PropertyDescriptor sortPropertyValue;

    public SortableBindingList()
    {
    }

    public SortableBindingList(IList<T> list)
    {
        foreach (object o in list)
        {
            this.Add((T)o);
        }
    }

    protected override void ApplySortCore(PropertyDescriptor prop,
        ListSortDirection direction)
    {
        Type interfaceType = prop.PropertyType.GetInterface("IComparable");

        if (interfaceType == null && prop.PropertyType.IsValueType)
        {
            Type underlyingType = Nullable.GetUnderlyingType(prop.PropertyType);

            if (underlyingType != null)
            {
                interfaceType = underlyingType.GetInterface("IComparable");
            }
        }

        if (interfaceType != null)
        {
            sortPropertyValue = prop;
            sortDirectionValue = direction;

            IEnumerable<T> query = base.Items;

            if (direction == ListSortDirection.Ascending)
            {
                query = query.OrderBy(i => prop.GetValue(i));
            }
            else
            {
                query = query.OrderByDescending(i => prop.GetValue(i));
            }

            int newIndex = 0;
            foreach (object item in query)
            {
                this.Items[newIndex] = (T)item;
                newIndex++;
            }

            isSortedValue = true;
            this.OnListChanged(new ListChangedEventArgs(ListChangedType.Reset, -1));
        }
        else
        {
            throw new NotSupportedException("Cannot sort by " + prop.Name +
                ". This" + prop.PropertyType.ToString() +
                " does not implement IComparable");
        }
    }

    protected override PropertyDescriptor SortPropertyCore
    {
        get { return sortPropertyValue; }
    }

    protected override ListSortDirection SortDirectionCore
    {
        get { return sortDirectionValue; }
    }

    protected override bool SupportsSortingCore
    {
        get { return true; }
    }

    protected override bool IsSortedCore
    {
        get { return isSortedValue; }
    }
}