convert linq query results to datatable C#

Question

I want to convert the linq query results to datatable so that I can assign datatable to GridView to show it on asp page.

However I am not able to convert the results

Answer 1

If you want to have you own extension method then you could always do something like this:

    public static DataTable ToDataTable<T>(this IQueryable items)
    {
        Type type = typeof(T);

        var props = TypeDescriptor.GetProperties(type)
                                  .Cast<PropertyDescriptor>()
                                  .Where(propertyInfo => propertyInfo.PropertyType.Namespace.Equals("System"))
                                  .Where(propertyInfo => propertyInfo.IsReadOnly == false)
                                  .ToArray();

        var table = new DataTable();

        foreach (var propertyInfo in props)
        {
            table.Columns.Add(propertyInfo.Name, Nullable.GetUnderlyingType(propertyInfo.PropertyType) ?? propertyInfo.PropertyType);
        }

        foreach (var item in items)
        {
            table.Rows.Add(props.Select(property => property.GetValue(item)).ToArray());
        }

        return table;
    }

You will need to reference both of these

using System.ComponentModel;
using System.Data;

Answer 2

First declare a new DataTable and add columns, in this :

DataTable dt = new DataTable();
dt.Columns.Add("FirstName");
dt.Columns.Add("LastName");
DataRow row = null;

Now I simply iterate through the query and fill a DataTable:

foreach (var rowObj in query)
{
    row = dt.NewRow();
    dt.Rows.Add(rowObj.FirstName, rowObj.LastName);
}

Answer 3

You should get DataTableExtensions.CopyToDataTable

Remove ToList().

CopyToDataTable is an IEnumerable<DataRow> extension (unfortunately).

There is a solution with custom CopyToDataTable extension method below.

var gradeData = (from data in oAngieCtxt.prc_ShopInstanceCustomersData(
                 Convert.ToInt32(this.ShopInstanceID), 10000, false)
                .Where( row => row.RecievedPoints != "n/a" )
                .GroupBy(row => new { row.Name })
                .Select(g => new
                {
                    Name = g.Key.Name,
                    TotalPoints = g.Sum(x => Convert.ToDouble(x.RecievedPoints) 
                    * (x.Weightage.ToString() == "0.00" ? 1 
                      : Convert.ToDouble(x.Weightage)))
                })
                 select data);

var dt = gradeData.CopyToDataTable();

Edit:

Here is a more useful implementation of CopyToDataTable There is no type constraint to DataRow.

  public static class DataSetLinqOperators
  {
    public static DataTable CopyToDataTable<T>(this IEnumerable<T> source)
    {
        //you find the ObjectShredder implementation on the blog wich was linked.
        return new ObjectShredder<T>().Shred(source, null, null);
    }

    public static DataTable CopyToDataTable<T>(this IEnumerable<T> source, 
                                     DataTable table, LoadOption? options)
    {
        return new ObjectShredder<T>().Shred(source, table, options);
    }

  }