How to populate DataTable with anonymous LINQ result

Question

I have the following LINQ query:

var timesheets = from timesheet in entities.Timesheets
    join timesheetTask in entities.Timesheet_Task on timesheet.Id e         


        

Answer 1

I'm using FastMember for this purpose. It uses IL instead of reflection (much faster) to iterate over all of the property and field values automatically. Code sample from the site:

IEnumerable<SomeType> data = ...
var table = new DataTable();
using(var reader = ObjectReader.Create(data))
{
    table.Load(reader);
}

Answer 2

If you really want to populate DataTable:

// your query
var timesheets = ...

// design table first
DataTable table = new DataTable();
table.Columns.Add(new DataColumn
    {
        ColumnName = "TaskName",
        DataType = typeof(String);
    });
...

List<DataRow> list = new List<DataRow>();
foreach (var t in timesheets)
{
    var row = table.NewRow();
    row.SetField<string>("TaskName", t.taskName); // extension method from System.Data.DataSetExtensions.dll
    ...

    list.Add(row);
}

DataTable table = list.CopyToDataTable(); // extension method too

---

Or more LINQ way:

timesheets
    .Select(t =>
        {
            var row = table.NewRow();
            ...
            return row;
        })
    .CopyToDataTable();

---

Or in same query syntax. Implement a method:

static DataRow NewRow(DataRow row, string taskName, ....)
{
    ...
}

Then query itself:

(from ...
 where ...
 select NewRow(table.NewRow(), task.Name, ...)
).CopyToDataTable();

Answer 3

Call .ToList().
The resulting List<T> can also be bound to a DataGridView, and is easier to work with than a DataTable.