How to use the results of a database query using Linq to fill a DataGrid? It should be no big deal since there is a useful CopyToDataTable extension method:

public static DataTable CopyToDataTable<T>(
    this IEnumerable<T> source
where T : DataRow

However, there is a problem: T has to be a DataRow. When returning query results from the database, especially with EF, your query results are not DataRows (and I wonder if the same is true for Linq to Sql too). So, in this case, you’ll have to fill the DataTable by hand. Thanks to this good blog post, I was able to fill it:

DataTable dataTable = new DataTable();
dataTable.TableName = "ResultsTable";
dataTable.Columns.Add("User", typeof(string));
dataTable.Columns.Add("TotalJobs", typeof(int));
var query = /* your linq query comes here. no restrictions! */

we have the DataTable and the query set up. Now, the tricky part!

var results = query.Select(anonym => new Func<DataRow, int, int, DataRow>(
    (DataRow row, int index, int count) => {
        row["User"] = index;
        row["TotalJobs"] = count;
        return row;
.Invoke(dataTable.NewRow(), anonym.Index, anonym.TotalJobs));
results.ToList().ForEach(row => dataTable.Rows.Add(row));

Absolutely a good piece of unreadable code :)

_query _variable are your Linq query results, which may be an IEnumerable of some of your data entities or even a anonymous type. It doesn’t matter! For each element of this enumeration, we’re creating a DataRow and assigning some values to its columns. Then, we call _Invoke _to indeed invoke our anonymous delegate Func, passing in our anonymous type properties, that are used later to fill the DataTable.

You’ll probably gonna need to read it a couple times to digest it a bit and still it will look “WTF did I really wrote this code?!?” after a couple days :)