C＃DataGridView DataGridViewTextCell到DataGridViewComboBoxCell可编辑文本

Question

I have a DataGridView with a TextBoxColumn. I would like to be able to click on the cell to enter edit mode, and when I do a drop down will appear with options for the user to pick, or if the user does not want one of those options, they are able to edit the cell (as if there was no drop down). Then when the user leaves the cell, the value (either what they typed, or what they chose) will be saved.

There are lots of answers to adding the user typed choice to the drop down list, but this is not what I want. I just want to have some common options for the user to consider before they go off and make their own choice.

I do not want to have a button to popup another input dialog. I do not want to chanbe the column to a ComboBoxColumn. I do not care if the dropdown arrow is shown at all times or not.

I have tried to change the TextBoxCell to a ComboBoxCell on EditingContolShowing, but this is proving to be a pointless effort.

Are there any suggestions for this?

Answer 1

One option you could use is AutoComplete. This can mimic most of the desired behavior on a DataGridViewTextCell, with exception of displaying all options on entering the textcell, and without the need of converting the cell type to a ComboBox.

This could be handled in the DataGridView EditingControlShowing event:

private void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
{
  if (e.Control is TextBox)
  {
    TextBox box = e.Control as TextBox;
    box.AutoCompleteCustomSource = new AutoCompleteStringCollection();
    box.AutoCompleteCustomSource.AddRange(new string[] { "Foo", "Bar", "Baz" });
    box.AutoCompleteMode = AutoCompleteMode.Suggest;
    box.AutoCompleteSource = AutoCompleteSource.CustomSource;
  }
}

Given, the user must enter text for any option to show. If the desired behavior requires all options to show upon entering the textbox, this would not be your best option. But if that is secondary to all other required behaviors (suggested options, accepts non-option entries, doesn't always have to show, etc), this is a viable solution.

Edit

This worked in all the following situations:

1. DataGridView is data bound.

Binding the DataSource:

public BindingList<Example> Examples { get; set; }

this.Examples = new BindingList<Example>();
dataGridView1.DataSource = this.Examples;

Where Example is a simple class:

public class Example
{
  public string First { get; set; }
  public string Last { get; set; }
  public string Test { get; set; }
}

2. Manually adding column(s).

Just an empty column:

DataGridViewTextBoxColumn col = new DataGridViewTextBoxColumn();
col.Name = "Extra";
col.HeaderText = "Extra";
this.dataGridView1.Columns.Add(col);

3. Both 1 and 2 combined.

Answer 2

Just set the cells you want to be a ComboBox to the DataGridViewComboBoxCell type:

var cb1 = new DataGridViewComboBoxCell();
cb1.Items.Add("Yes");
cb1.Items.Add("No");
dgv.Rows[1].Cells[1] = cb1;

var cb2 = new DataGridViewComboBoxCell();
cb2.Items.Add("Blue");
cb2.Items.Add("Red");
dgv.Rows[3].Cells[1] = cb2;

Then use the EditingControlShowing event to change the style of the DropDown to allow editing:

void dgv_EditingControlShowing(object sender,
                               DataGridViewEditingControlShowingEventArgs e) {
  ComboBox cb = e.Control as ComboBox;
  if (cb != null) {
    cb.DropDownStyle = ComboBoxStyle.DropDown;
  }
}

Use the CellValidating event to add any typed items into the list that aren't already there:

void dgv_CellValidating(object sender, DataGridViewCellValidatingEventArgs e) {
  var cb = dgv.Rows[e.RowIndex].Cells[e.ColumnIndex] as DataGridViewComboBoxCell;
  if (cb != null && !cb.Items.Contains(e.FormattedValue)) {
    cb.Items.Add(e.FormattedValue);
    if (dgv.IsCurrentCellDirty) {
      dgv.CommitEdit(DataGridViewDataErrorContexts.Commit);
    }
    dgv.Rows[e.RowIndex].Cells[e.ColumnIndex].Value = e.FormattedValue;
  }
}