Strange issue with a datagridview and a tabcontrol C#

Question

I have a strange problem. I have a TabControl with two TabPages. Each page has a datagridview. Both datagridviews are populated with XML files.

I want to have the AutoSizeColumnsMode set to "Fill" for both DataGridViews. I want to set the width of columns in my code.

And everything works fine for the TabPage1 but setting width for the DataGridView on TabPage2 throws the NullReferenceException.

I really don't get it because I do the same thing as for datagridview1 and there works fine but datagridview2 throws the exception. Additionally, there is no exception if I choose any AutoSizeColumnsMode value but Fill.

Here's the code:

        XmlReader xmlFile = XmlReader.Create("File1.xml", new XmlReaderSettings());
        DataSet ds = new DataSet();
        ds.ReadXml(xmlFile);



            dataGridView1.DataSource = ds.Tables[0];
            dataGridView1.Sort(dataGridView1.Columns[1], ListSortDirection.Ascending);

           dataGridView1.Columns[0].Width = 35;
            dataGridView1.Columns[1].Width = 248;
            dataGridView1.Columns[2].Width = 110;
            dataGridView1.Columns[3].Width = 140;
            dataGridView1.Columns[9].Width = 127;
            dataGridView1.Columns[0].Visible = false;
            dataGridView1.Columns[1].Visible = true;
            dataGridView1.Columns[2].Visible = true;
            dataGridView1.Columns[3].Visible = true;
            dataGridView1.Columns[4].Visible = false;
            dataGridView1.Columns[5].Visible = false;
            dataGridView1.Columns[6].Visible = false;
            dataGridView1.Columns[7].Visible = false;
            dataGridView1.Columns[8].Visible = false;
            dataGridView1.Columns[9].Visible = true;
            dataGridView1.Columns[10].Visible = true;
            dataGridView1.Columns[10].Width = 100;

            xmlFile.Close();

        XmlReader xmlFile2= XmlReader.Create("File2.xml", new XmlReaderSettings());
        DataSet ds2 = new DataSet();
        ds2.ReadXml(xmlFile2);
        dataGridView2.DataSource = ds2.Tables[0];


            dataGridView2.Columns[0].Width = 135; // The exception is thrown here
            dataGridView2.Columns[9].Width = 200;
            dataGridView2.Columns[8].Width = 300;
            dataGridView2.Columns[7].Width = 70;
            dataGridView2.Columns[6].Width = 70;
            dataGridView2.Columns[5].Width = 124;
            dataGridView2.Columns[4].Width = 81;
            dataGridView2.Columns[3].Width = 70;
            dataGridView2.Columns[2].Width = 70;
            dataGridView2.Columns[1].Width = 124;

            dataGridView2.Columns[0].Visible = true;
            dataGridView2.Columns[1].Visible = true;

            dataGridView2.Columns[2].Visible = true;
            dataGridView2.Columns[3].Visible = true;
            dataGridView2.Columns[4].Visible = true;

            dataGridView2.Columns[5].Visible = false;
            dataGridView2.Columns[6].Visible = false;
            dataGridView2.Columns[7].Visible = false;
            dataGridView2.Columns[9].Visible = false;


            xmlFile2.Close();

That implies that the column doesn't exist. Are you getting data back from `File2.xml`? In other words, does ds2 actually contain the loaded data? — Michael Todd, Jun 10 '13 at 21:22
Yes, I'm getting data back from File2.xml. The problem is when I try to change the widths of columns. Even changing visibility works. — Michal_Drwal, Jun 10 '13 at 23:39

score 2 · Accepted Answer · answered Jun 11 '13 at 02:18

2

This is because a data-bound control(dataGridView2) is not updated until the control is made visible. See this. You can refresh the binding, for example, by programmatically switching to TabPage2 and back to the first tab.

answered Jun 11 '13 at 02:18

Jacob Seleznev

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score 0 · Answer 2 · answered Jun 10 '13 at 18:50

0

THe only thing I can se at the moment is that you are not doing this on tabpage 2

dataGridView1.Sort(dataGridView1.Columns[1], ListSortDirection.Ascending);

try

dataGridView2.Sort(dataGridView2.Columns[1], ListSortDirection.Ascending);

answered Jun 10 '13 at 18:50

8bitcat

2,206
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It's not important and has no meaning. – Michal_Drwal Jun 10 '13 at 18:52

Strange issue with a datagridview and a tabcontrol C#

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