datagridview 中的两个组合框

Question

我正在使用 windowsforms 中的 datagridview 中的组合框进行 delaeaing 假设我在一个 datagridview 中有两个组合框，所以我的问题是
如何根据此datagridview中另一个comboboxcolum的选定值填充datagridview中的comboboxcolumn

Answer 1

好吧，我想我有点晚了，但是您应该做的是在您的列上附加一个值更改事件处理程序。当您选择一个新值时，处理程序应该触发，然后您使用传递给函数的参数来确定更改了哪一行并更改该行中的第二个组合框。我会提供一个例子，但我几乎可以肯定你无论如何都不会回来看这个答案。

编辑： 没想到你真的会为此卷土重来，但这是实现动态组合框的一种方法。我不能说我对这个答案感到完全自豪，但是因为它不适用于数据绑定（您必须自己添加每一行并设置正确的初始值。）但至少这个解决方案可以为您指明正确的方向或者一个新的。

public partial class DualComboBoxGridViewForm : Form
{
    private Dictionary<Country, List<City>> locations;

    public DualComboBoxGridViewForm()
    {
        InitializeComponent();
        InitializeLocations();

        dataGridView1.Rows.Add(new DataGridViewRow());
    }

    private void InitializeLocations()
    {
        // Loading these from a database would be highly recommended, I 
        // just did it like this with a dictionary to it would be easier 
        // to show.
        locations = new Dictionary<Country, List<City>>();

        List<City> americanCities = new List<City>();
        americanCities.Add(new City { ID = 0, Name = "Please Select A City" });
        americanCities.Add(new City { ID = 1, Name = "Boston" });
        americanCities.Add(new City { ID = 2, Name = "New York" });

        List<City> japaneseCities = new List<City>();
        japaneseCities.Add(new City { ID = 0, Name = "Please Select A City" });
        japaneseCities.Add(new City { ID = 1, Name = "Tokyo" });
        japaneseCities.Add(new City { ID = 2, Name = "Kyoto" });

        locations.Add(new Country { ID = 0, Name = "Please Select A Country" }, new List<City>());
        locations.Add(new Country { ID = 1, Name = "USA" }, americanCities);
        locations.Add(new Country { ID = 2, Name = "Japan" }, japaneseCities);
    }

    private void InitializeDataGridView()
    {
        dataGridView1.AutoGenerateColumns = false;
        dataGridView1.EditingControlShowing += dataGridView1_EditingControlShowing;

        // Create columns
        DataGridViewTextBoxColumn eventNameColumn = new DataGridViewTextBoxColumn();
        eventNameColumn.HeaderText = "Event";

        DataGridViewComboBoxColumn countryComboBox = new DataGridViewComboBoxColumn();
        countryComboBox.Name = "Country";
        countryComboBox.HeaderText = "Country";
        countryComboBox.ValueMember = "ID";
        countryComboBox.DisplayMember = "Name";
        foreach (Country country in locations.Keys)
        {
            countryComboBox.Items.Add(country);
        }

        DataGridViewComboBoxColumn cityComboBox = new DataGridViewComboBoxColumn();
        cityComboBox.Name = "City";
        cityComboBox.HeaderText = "City";
        cityComboBox.ValueMember = "ID";
        cityComboBox.DisplayMember = "Name";

        dataGridView1.Columns.Add(eventNameColumn);
        dataGridView1.Columns.Add(countryComboBox);
        dataGridView1.Columns.Add(cityComboBox);
    }

    // Triggers when a column enters edit mode (new value not yet assigned).
    private void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs args)
    {
        // we only want to change the city box if a country value is changed
        if (dataGridView1.CurrentCell.ColumnIndex == dataGridView1.Columns["Country"].Index)
        {
            ComboBox countryBox = args.Control as ComboBox;
            countryBox.SelectedIndexChanged += countryComboBox_SelectedIndexChanged;
        }
    }

    private void countryComboBox_SelectedIndexChanged(object sender, EventArgs args)
    {
        ComboBox box = sender as ComboBox;

        DataGridViewComboBoxCell cityCell = dataGridView1.Rows[dataGridView1.CurrentCell.RowIndex].Cells[dataGridView1.Columns["City"].Index] as
            DataGridViewComboBoxCell;
        cityCell.Items.Clear();
        foreach (City city in locations[box.SelectedItem as Country])
        {
            cityCell.Items.Add(city);
        }

        if (cityCell.Items.Count > 0)
        {
            cityCell.Value = cityCell.Items[0];
        }

        // Remove event handler to prevent memory leak
        box.SelectedIndexChanged -= countryComboBox_SelectedIndexChanged;
    }
}

public class Country
{
    public int ID { get; set; }
    public string Name { get; set; }
}

public class City
{
    public int ID { get; set; }
    public string Name { get; set; }
}