2-state DataGridBoolColumn style

[Douglas Dean]

Can anybody tell me how to implement a normal (2-state) checkbox for a column on my DataGrid? I have tried using every kind of .NET admonition ("AllowNull = false" on the style, on the column, etc.), but I always get a 3-state check box that at best is a hassle (extra clicking required to get where you want) and at worst causes an error if they leave it in the null state. I don't relish the prospect of watching my users' eyes glaze over as I explain to them the difference between "false" and "DBNull". Any help will be greatly appreciated! Doug

[Robert Rohde]

Hmmm... setting AllowNull on the DataGridBoolColumn to false should work (I remember I used it once and it worked). To avoid the nullstate you could also set the NullValue property to either true or false.

[Josh Smith]

You can set the AllowNull property on the DataGridBoolColumn to false and it will prevent the tri-state checkbox. I used a little reflection to get a reference to the internal DataGridTableStyle used by the grid (if there's a way to access that field via the public interface, please let me know how).

private void Form1_Load(object sender, System.EventArgs e)
{
DataTable tbl = new DataTable();
tbl.Columns.Add( "TwoState", typeof(bool) );
tbl.Rows.Add( new object[] { true } );
tbl.Rows.Add( new object[] { false } );
this.dataGrid1.DataSource = tbl;

DataGridTableStyle tableStyle = typeof(DataGrid).GetField( 
	"myGridTable",
	System.Reflection.BindingFlags.Instance | 
	System.Reflection.BindingFlags.NonPublic).GetValue( this.dataGrid1 ) 
	as DataGridTableStyle;

(tableStyle.GridColumnStyles\[ "TwoState" \] as DataGridBoolColumn).AllowNull = false;

}

Josh

[Douglas Dean]

Thanks for all the answers, but setting the AllowNull is definitely not working wither for Column or Style. I am becoming convinced that this is because I am working with .NET Framework 1.1. :-(