Why DataGridColumn not getting removed from DataGridView

问题

I have custom DataGridView control and in that control there is RefreshGrid() method which fill DataGridView by using DataSource. Now I am tring to remove few columns from that DataGridView after DataSource binding but unable to remove those, those column not getting removed but add at the end of DataGridView, when I call RefreshGrid() method again then those column get removed from DataGridView. Here is code for method RefreshGrid()

    public void RefreshGrid()
    {
        DataTable _table = AccessConnectionManagers.GetDataTableBySQLQuery("select Colm1,Colm2,Colm3 from TableName");
        //Data Source Binding with DataGridView
        this.DataSource = _table;

        if (!string.IsNullOrEmpty("Colm1"))
        {
            var _colmArray = GridRemoveColumnName.Split(new char[] { ',', ';' }, StringSplitOptions.RemoveEmptyEntries).Where(a => this.Columns.Contains(a)).Select(a => a).ToArray();

            foreach (string colm in _colmArray)
            {
                //Remove column after Source Binding
                this.Columns.Remove(colm);
            }
        }
    }

Call for RefreshGrid()

    public Form1()
    {
        InitializeComponent();
        myDataGridView1.RefreshGrid();
    }

Please find the error and suggest me the solution.

回答1:

I found answer for this question

I need to call RefreshGrid() method on Form Load not on Form constructor, after calling it on Form Log my problem get solved. But I dont know why it wasnt working on Form constructor.

I guess you try to access columns that do not exist yet. You are using the DataGridView.AutoGenerateColumns functionnality and even if you set the DataSource property, The DatagridView won't create columns until the grid is displayed. It's why it doesn't work in form constructor, but works in form_Load event or after that the grid has been displayed.

Using form_Load is maybe a possible workaround, but I reommand you to use the DataGridView.DataBindingComplete event which is especially designed to handle this situation.

回答2:

You should retrieve only columns from data table that you want to display in DataGridView.

var results = _table
    .AsEnumerable()
    .Where("Add your condition")
    .Select("your columns names");

this.DataSource = results;

So now you don't need to remove any columns from DataGridView

回答3:

I found answer for this question

I need to call RefreshGrid() method on Form Load not on Form constructor, after calling it on Form Load my problem get solved. But I dont know why it wasnt working on Form constructor.

来源：https://stackoverflow.com/questions/18359031/why-datagridcolumn-not-getting-removed-from-datagridview

标签

winforms

datagridview