WPF Datagrid：当用户对列进行排序时，如何应用“第二次”排序？

Question

我的数据有几列：例如Brand、Colour、Power、ReleaseYear。因此，当用户单击Datagrid的列标题时，Datagrid的自动功能会自动对数据进行排序。尽管如此，我想立即应用按 ReleaseYear 进行的第二次排序，与单击的标题无关。有没有办法添加这种排序，例如 通过处理排序事件？

Answer 1

在 C# 中，特别是在使用 DataGridView 或 DataGrid（对于 WPF 应用程序）时，您可以通过挂钩排序事件并修改排序逻辑来处理排序并应用二次排序。以下是如何为 WinForms (DataGridView) 和 WPF (DataGrid) 实现此目的。

1. 对于 WinForms (DataGridView) 如果您使用的是 DataGridView，则可以处理 ColumnHeaderMouseClick 事件以按单击的列对数据进行排序，并按 ReleaseYear 应用二次排序。

以下是如何实现它的示例：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;

public partial class MainForm : Form
{
    private List<Product> products;

    public MainForm()
    {
        InitializeComponent();
        LoadData();
    }

    private void LoadData()
    {
        products = new List<Product>
        {
            new Product { Brand = "Apple", Colour = "Red", Power = "500W", ReleaseYear = 2020 },
            new Product { Brand = "Samsung", Colour = "Blue", Power = "600W", ReleaseYear = 2021 },
            new Product { Brand = "LG", Colour = "Green", Power = "700W", ReleaseYear = 2019 },
            // Add more products here...
        };

        dataGridView1.DataSource = products;
    }

    private void dataGridView1_ColumnHeaderMouseClick(object sender, DataGridViewCellMouseEventArgs e)
    {
        // First, sort by the clicked column
        string sortColumn = dataGridView1.Columns[e.ColumnIndex].DataPropertyName;
        
        // Determine if the column is already sorted ascending or descending
        ListSortDirection sortDirection = ListSortDirection.Ascending;
        if (dataGridView1.SortOrder == SortOrder.Ascending)
        {
            sortDirection = ListSortDirection.Descending;
        }

        // Apply primary sorting based on the clicked column
        var sortedList = SortByColumn(products, sortColumn, sortDirection);

        // Apply secondary sorting by ReleaseYear (ascending)
        var secondarySortedList = sortedList.OrderBy(p => p.ReleaseYear).ToList();

        // Update the DataGridView with the newly sorted data
        dataGridView1.DataSource = secondarySortedList;
    }

    private List<Product> SortByColumn(List<Product> data, string column, ListSortDirection direction)
    {
        switch (column)
        {
            case "Brand":
                return direction == ListSortDirection.Ascending ?
                    data.OrderBy(p => p.Brand).ToList() :
                    data.OrderByDescending(p => p.Brand).ToList();
            case "Colour":
                return direction == ListSortDirection.Ascending ?
                    data.OrderBy(p => p.Colour).ToList() :
                    data.OrderByDescending(p => p.Colour).ToList();
            case "Power":
                return direction == ListSortDirection.Ascending ?
                    data.OrderBy(p => p.Power).ToList() :
                    data.OrderByDescending(p => p.Power).ToList();
            case "ReleaseYear":
                return direction == ListSortDirection.Ascending ?
                    data.OrderBy(p => p.ReleaseYear).ToList() :
                    data.OrderByDescending(p => p.ReleaseYear).ToList();
            default:
                return data;
        }
    }
}

public class Product
{
    public string Brand { get; set; }
    public string Colour { get; set; }
    public string Power { get; set; }
    public int ReleaseYear { get; set; }
}

说明：

1. 单击标题进行排序：单击列标题时，会触发 ColumnHeaderMouseClick 事件。此事件确定单击了哪一列并按该列对数据进行排序。
2. 主排序：根据当前的排序顺序（升序或降序）确定排序方向。
3. 二次排序：在应用一次排序后，列表进一步按 ReleaseYear 列升序排序。
4. 更新 DataGridView：然后将排序后的数据设置回 DataGridView。