CODEWITHSUNDEEP
c#datagridviewdatatable
HodlDwon
HodlDwon

Reputation: 1171

DataGridView Odd Display Behaviour When Trying to Clear

I have a DataGridView that is bound to a DataTable.

I later add a new button column directly to the DGV. The next time I refresh the table I want to clear all the previous data from the DGV.

For the table I just do var table = new DataTable(); but doing this with the DataGridView when the DGV is defined as a local inside the method causes it to never display on the form.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            //dataGridView1 = new DataGridView(); //<-- uncommenting this line breaks the form's dgv from displaying anything

            DataTable table = new DataTable();
            table.Columns.Add("C_" + table.Columns.Count);
            table.Rows.Add("R1");
            table.Rows.Add("R2");
            dataGridView1.DataSource = table;

            DataGridViewButtonColumn oCol = new DataGridViewButtonColumn();
            oCol.Name = "Buttons";
            oCol.Text = "(...)";
            oCol.UseColumnTextForButtonValue = true;
            dataGridView1.Columns.Add(oCol);
        }
    }
}

Is this a bug or how should I refresh/reset/clear a dgv properly?

EDIT:

Code snippet above has been edited from the original. Uncomment the line in the code to see the different behaviour of button1 when in RunMode.

Upvotes: 1

Views: 257

Answers (2)

spajce
spajce

Reputation: 7092

I think this is not a bug. But unfortunately I can't explain :)

Just use the Controls.Add(..)

    DataGridView dgv = new DataGridView(); 
    private void button1_Click(object sender, EventArgs e)
    {
        DataTable table = new DataTable();
        table.Columns.Add("C_" + table.Columns.Count);
        table.Rows.Add("R1");
        table.Rows.Add("R2");
        dgv.DataSource = table;

        DataGridViewButtonColumn oCol = new DataGridViewButtonColumn();
        oCol.Name = "Buttons";
        oCol.Text = "(...)";
        oCol.UseColumnTextForButtonValue = true;
        dgv.Columns.Add(oCol);

        Controls.Add(dgv); //<--Try to check this.
    }

    private void button2_Click(object sender, EventArgs e)
    {
        dgv.Columns.Clear();
    }

Upvotes: 0

scartag
scartag

Reputation: 17680

dataGridView1.DataSource = null;

or you could opt to clear the columns/rows.

dataGridView1.Rows.Clear();
dataGridView1.Columns.Clear();

Upvotes: 1

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