distinct value from a column in a grid using linq

I am using the below query to find the the distinct value count from a dataset column. How to find开发者_如何学编程 similarly to a grid column.

var distinctRows = (from DataRow dRow in _ds.Tables[0].Rows
                    select dRow["colName"]).Distinct();

Ok..I'm still not sure why you want to do it without requerying the DataSource, but here's one way that might point you in the right direction. gv1 is the ID of your GridView, and for demonstration purposes I'll use the first column:

string[] rowValues = new string[gv1.Rows.Count];

for (int i = 0; i < gv1.Rows.Count; i++)
{
    rowValues[i] = gv1.Rows[i].Cells[0].Text;
}

var distinctRows = (from r in rowValues
                    select r).Distinct();

This of course assumes that it's one cell per column, which may be a false (or at least bad) assumption.

UPDATE Just saw this Can't seem to use Linq with ASP.Net Navigation menu answered by Jon Skeet, and think it might apply to the issue here.

var distinctRows = (from GridViewRow r in gv1.Rows
                    select r.Cells[0].Text).Distinct();

Courtesy of Jon's answer, to use LINQ in this case you need to Cast to IEnumerable (as I'm willing to bet the GridViewRowsCollection doesn't implement IEnumerable) by explicitly specifying the item, as above.

Your grid is probably bound to a data source in which case it makes more sense to use the linq query against the data source rather than the grid itself