Can't get value from ComboBox control

Question

I try to use combobox in winforms project.

Here is my code:

 private void ShowContoursForm_Load(object sender, EventArgs e) { cbxSelectShape.DisplayMember = dataSetObject.ObjectShapes.ShapeNameColumn.ColumnName; cbxSelectShape.ValueMember = dataSetObject.ObjectShapes.ShapeIDColumn.ColumnName; cbxSelectShape.DataSource = dataSetObject.ObjectShapes; } private void cbxSelectShape_SelectedValueChanged(object sender, EventArgs e) { var id= (int)cbxSelectShape.SelectValue; }

When I choose item from ComboBox SelectedValueChanged is fired,and id variable gets null.

I need to get value of selected item but I always get null in id variable. Any idea why do I get wrong result and how to fix this code?

Try using the SelectedIndexChanged event: msdn.microsoft.com/en-us/library/… — Abbas
– Abbas, Commented Jan 24, 2013 at 13:49
While this almost certainly isn't the best way to achieve what you try to achieve, it should work IMO. — Rev
– Rev, Commented Jan 24, 2013 at 13:57
What's the underlying type of ShapeIDColumn.ColumnName? Is it string? If so, it looks like you're trying to cast each value from string to int. — B L
– B L, Commented Jan 24, 2013 at 14:04

aaa · Accepted Answer · 2013-01-24 13:55:38Z

You can get the index of ComboBox this way:

private void cbxSelectShape_SelectedValueChanged(object sender, EventArgs e) { var id= ((ComboBox)sender).SelectedIndex; }

Sergey Berezovskiy · Accepted Answer · 2013-01-24 14:16:28Z

You should use SelectedValue property of combobox to get value, associated with ValueMember (ShapeID in your case):

var id = ((ComboBox)sender).SelectedValue;

SelectedIndex returns index of item selected in combobox. Also if this handler used for one combobox, you don't need to cast sender - simply use your combobox variable:

var id = cbxSelectShape.SelectedValue;

@Michael are you sure you have data in your table? Set a breakpoint and watch for cbxSelectShape.Items[cbxSelectShape.SelectedIndex]. What do you see? BTW your id variable cannot be null if you are casting to int.

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