如何将DataGridViewComboBoxColumn绑定到父行的绑定对象的list属性？

Question

Given the following classes:

public class Shirt
{
    public string Description { get; set; }
    public List<Color> ColorOptions { get; set; }
    public int SelectedColorId { get; set; }
}

public class Color
{
    public int Id { get; set; }
    public string Label { get; set; }
}

Why can't I get the combobox to show up in the DataGridView using the following code?

        List<Shirt> foundShirts = _dbShirtRepo.GetShirts();

        var nameColumn = new DataGridViewTextBoxColumn();
        nameColumn.DataPropertyName = "Description";
        nameColumn.HeaderText = "Description";

        var colorSelectColumn = new DataGridViewComboBoxColumn();
        colorSelectColumn.DataPropertyName = "ColorOptions";
        colorSelectColumn.DisplayMember = "Label";
        colorSelectColumn.ValueMember = "Id";


        dataGridView1.Columns.Add(nameColumn);
        dataGridView1.Columns.Add(colorSelectColumn);

        dataGridView1.DataSource = foundShirts;

Answer 1

Try something like this:

private void dataGridView1_CellClick(object sender, DataGridViewCellEventArgs e)
{
    if (e.ColumnIndex == 1)
    {
        DataGridViewComboBoxCell combo = this.dataGridView1[1, e.RowIndex] as DataGridViewComboBoxCell;
        combo.DataSource = ((Shirt)dataGridView1.Rows[e.RowIndex].DataBoundItem).ColorOptions;
    }
} 

As you can see, you have to provide DataSource per request because you can only have one at a time. There's no way to pre-set different data sources for each combo in each row.

You can improve the above solution but the concept is the same:

• User clicks, hovers or otherwise "activates" the cell
• Set up the DataSource of the column's combo before user has a chance to open it

This way user is not aware of any shenanigans going on and you can offer different choice for every individual row.

I'm not 100% sure of how DataGridViewComboBoxCell operates, it's entirely possible that it caches and persists its data sources but experiment a bit before relying on it.

Answer 2

You have not set the DataSource property for the DataGridViewComboBoxColumn . There are different ways to solve your problem.

Set the DataSource of the DataGridViewComboBoxColumn to foundShirts.ColorOptions . With this you get to see only colors available in the foundShirts list.

var colorSelectColumn = new DataGridViewComboBoxColumn();
colorSelectColumn.DataPropertyName = "ColorOptions";
colorSelectColumn.DisplayMember = "Label";
colorSelectColumn.ValueMember = "Id";
colorSelectColumn.DataSource = foundShirts.ColorOptions;

If you want to see all the possible colors you could have, prepare a separate list of all possible colors and set it as the DataGridViewComboBoxColumn DataSource .

List<Color> allAvailableColorOptions = new List<Color>();
// add all the possible colors to this list.

var colorSelectColumn = new DataGridViewComboBoxColumn(); 
colorSelectColumn.DataPropertyName = "ColorOptions";   
colorSelectColumn.DisplayMember = "Label";
colorSelectColumn.ValueMember = "Id";
colorSelectColumn.DataSource = allAvailableColorOptions;