datagridview不允许用户删除行

Question

I have a datagridview bound to a datatable. The columns are not autogenerated, I create them in code. I want my user's to be able to add and delete a row, so I have AllowUserToAddRows = true, AllowUserToDeleteRows = true.

The problem is: when they select a row and press DEL, the information is replaced by the row cell's default values. The row does not go away.

What is this behavior (why/what is happening), and how can I get around it?

Here is my grid creation code:

    private void resetDowntimeGrid()
    {
        downtimeEntries = new DataTable();

        downtimeEntries.Columns.Add("Category", typeof(int));
        downtimeEntries.Columns.Add("HoursDown");
        downtimeEntries.Columns.Add("Reason");

        //deptDowntimeCategories.Select("", "ListOrder ASC");

        gridDowntime.Columns.Clear();

        DataGridViewComboBoxColumn cboCategory = new DataGridViewComboBoxColumn();
        {
            cboCategory.HeaderText = "Category";
            cboCategory.DataSource = deptDowntimeCategories;
            cboCategory.DisplayMember = "Name";
            cboCategory.ValueMember = "CategoryID";
            cboCategory.DataPropertyName = "Category";
            cboCategory.Width = Convert.ToInt16(gridDowntime.Width * 0.20);
            cboCategory.DisplayStyle = DataGridViewComboBoxDisplayStyle.ComboBox;
            cboCategory.AutoComplete = true;

            gridDowntime.Columns.Add(cboCategory);
        }

        DataGridViewTextBoxColumn txtDowntime = new DataGridViewTextBoxColumn();
        txtDowntime.HeaderText = "HoursDown";
        txtDowntime.DataPropertyName = "HoursDown";
        txtDowntime.Width = Convert.ToInt16(gridDowntime.Width * 0.15);
        gridDowntime.Columns.Add(txtDowntime);

        DataGridViewTextBoxColumn txtReason = new DataGridViewTextBoxColumn();
        txtReason.HeaderText = "Reason";
        txtReason.DataPropertyName = "Reason";
        txtReason.Width = Convert.ToInt16(gridDowntime.Width * 0.60);
        gridDowntime.Columns.Add(txtReason);

        gridDowntime.DataSource = downtimeEntries;

        lblStatus.Text = "Downtime grid reset.";
    }

Answer 1

I created an empty winform and just put the grid code into it. The difference was how I had the DataGridView.EditMode set. I had it = EditOnEnter , but the delete works perfectly if I set it = EditOnKeystroke.

Answer 2

Here's a quick sample that I did, minus two of your columns, using part of your code. I could not duplicate your problem. You may want to validate that you are actually selecting a value, clicking the value from the drop down, and then click 'Delete'. (In this case, I simply dragged a DataGridView from the toolbox to the form. I made no other modifications.)

public partial class Form1 : Form
{
       public Form1()
       {
           InitializeComponent();
       }

       private void button1_Click(object sender, EventArgs e)
       {
           DataTable myTable = new DataTable("MyTable");
           myTable.Columns.Add("CategoryID", typeof(int));
           myTable.Columns.Add("CategoryName", typeof(string));
           myTable.Rows.Add(new object[] { 1, "Small" });
           myTable.Rows.Add(new object[] { 2, "Medium" });
           myTable.Rows.Add(new object[] { 3, "Large" });

           DataGridViewComboBoxColumn cboCategory = new DataGridViewComboBoxColumn();
           cboCategory.HeaderText = "Category";
           cboCategory.DataSource = myTable;
           cboCategory.DisplayMember = "CategoryName";
           cboCategory.ValueMember = "CategoryID";
           cboCategory.DataPropertyName = "Category";
           cboCategory.Width = Convert.ToInt16(dataGridView1.Width * 0.20);
           cboCategory.DisplayStyle = DataGridViewComboBoxDisplayStyle.ComboBox;
           cboCategory.AutoComplete = true;

           dataGridView1.Columns.Add(cboCategory);

       }
}

Answer 3

Another reason why hitting Delete doesn't remove the rows is if you have the RowHeadersVisible property set to False, thus not showing the * in the left most column. With that fixed, @MAW74656's solution worked for me.