Prevent to add a column twice to the datagridview

Question

I have a MetroFramework.Controls.MetroGrid in my windows forms application. In frmPatientList_Shown I call a method loadPatientList(). I also add a DataGridViewLinkColumn after binding the dtb to the gridview. Clicking the link opens a new form where I update Patient data, and on formEditPatient.FormClosed I call the loadPatientList() method again, This time the DataGridViewLinkColumn is being added twice. How can I prevent to Add the link twice ? Here is my code:

private void frmPatientList_Shown(object sender, EventArgs e)
{
    loadPatientList();
}
private void loadPatientList()
{
    DataTable dtb = Patient.getPatientList();
    bindToGrid(dtb);
}
private void bindToGrid(DataTable dtb)
{   
    dataGridView1.DataSource = null;
    using (dtb)
    {
        dataGridView1.DataSource = dtb;
        dataGridView1.AutoGenerateColumns = false;
        dataGridView1.AllowUserToAddRows = false;

        dataGridView1.Columns[0].Name = "PatientId";
        dataGridView1.Columns[0].HeaderText = "ID";
        dataGridView1.Columns[0].DataPropertyName = "PatientId";
        //  more code here.
    }

    DataGridViewLinkColumn EditLink = new DataGridViewLinkColumn();
    EditLink.UseColumnTextForLinkValue = true;
    EditLink.HeaderText = " Edit ";
    EditLink.DataPropertyName = "lnkColumn";
    EditLink.LinkBehavior = LinkBehavior.SystemDefault;
    EditLink.Text = "Edit";
    dataGridView1.Columns.Add(EditLink);
}
private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
    if (e.ColumnIndex == 8 && e.RowIndex >= 0)
    {
        using (frmEditPatient formEditPatient = new frmEditPatient(id))
        {
             formEditPatient.FormClosed += FormEditPatient_FormClosed;
             formEditPatient.ShowDialog();
        }
     }
 }

 private void FormEditPatient_FormClosed(object sender, FormClosedEventArgs e)
 {
     loadPatientList();
 }

Any help would be appreciated.

Answer 1

In frmPatientList_Shown function you add the link

private void frmPatientList_Shown(object sender, EventArgs e)
{
    DataGridViewLinkColumn EditLink = new DataGridViewLinkColumn();
    EditLink.UseColumnTextForLinkValue = true;
    EditLink.HeaderText = " Edit ";
    EditLink.DataPropertyName = "lnkColumn";
    EditLink.LinkBehavior = LinkBehavior.SystemDefault;
    EditLink.Text = "Edit";
    dataGridView1.Columns.Add(EditLink);

    loadPatientList();
}

In bindToGrid function you do not add the link

private void bindToGrid(DataTable dtb)
{   
    dataGridView1.DataSource = null;
    using (dtb)
    {
        dataGridView1.DataSource = dtb;
        dataGridView1.AutoGenerateColumns = false;
        dataGridView1.AllowUserToAddRows = false;

        dataGridView1.Columns[0].Name = "PatientId";
        dataGridView1.Columns[0].HeaderText = "ID";
        dataGridView1.Columns[0].DataPropertyName = "PatientId";
        //  more code here.
    }

    //DataGridViewLinkColumn EditLink = new DataGridViewLinkColumn();
    //EditLink.UseColumnTextForLinkValue = true;
    //EditLink.HeaderText = " Edit ";
    //EditLink.DataPropertyName = "lnkColumn";
    //EditLink.LinkBehavior = LinkBehavior.SystemDefault;
    //EditLink.Text = "Edit";
    //dataGridView1.Columns.Add(EditLink);
}

I hope it will help you.

Answer 2

You check if the column exist,

bool hasEditColumn = false;
        foreach (DataGridViewColumn item in dataGridView1.Columns)
        {
            if (item.GetType() == typeof(DataGridViewLinkColumn) && item.HeaderText == "Edit")
            {
                hasEditColumn = true;
                break;
            }
        }
        if (!hasEditColumn)
        {
            DataGridViewLinkColumn EditLink = new DataGridViewLinkColumn();
            EditLink.UseColumnTextForLinkValue = true;
            EditLink.HeaderText = "Edit";
            EditLink.DataPropertyName = "lnkColumn";
            EditLink.LinkBehavior = LinkBehavior.SystemDefault;
            EditLink.Text = "Edit";
            dataGridView1.Columns.Add(EditLink);
            dataGridView1.Refresh();
        }