Question

I’m getting an “InvalidCastException” during run time on the following code:

My C# WinForm code contains a comboBox which is populated from a database with the following code:

public void PopulateCompetitionFormatDd()
{
     var _competitionFormat            = new CompetitionFormatBL();
     cbCompetitionFormat.DataSource    = _competitionFormat.GetByAllCompetitionFormats();
     cbCompetitionFormat.ValueMember   = "CompetitionFormatId";
     cbCompetitionFormat.DisplayMember = "CompetitionFormatType";
}

The ValueMember (CompetitionFormatId) is a list of numbers and the DisplayMember (CompetitionFormatType) is a string of text. When I change the item in this comboBox during run time I get the error “InvalidCastException“.

private void cbCompetitionFormat_SelectedIndexChanged(object sender, EventArgs e)
{
     int competitionFormat = 1;
     competitionFormat = (int)cbCompetitionFormat.SelectedValue;
}

Any ideas what i’m doing wrong and how I can get around it?

Answer 1

I finally got the answer to this and it’s answered on this site to another similar question. Find answer here: Stop comboBox's selectedIndexChanged event from firing when the form loads

The answer is:
If you want to react only when the user changes the selected item in the combo box, then it is better to subscribe to SelectionChangeCommitted rather than SelectedIndex(or Value)Changed.