OrderBy named index

Question

I have a DataGridView that holds data returned from a stored procedure on a database. The columns are different for each return value, so do not have strongly-typed names. I'm currently struggling to order these, as the numeric columns are being ordered as strings, eg. 1 -> 10 -> 11 -> 15 -> 2 -> 25 -> 3, and not by value. I've confirmed that the ValueType of the column is being set correctly. I have tried this:

var sortedRows = from row in _rowArray
                             orderby columnIndex
                             select row;
                _rowArray = sortedRows.ToArray();

where _rowArray is an array of DataRows, and is the DataSource of the DataGridView, and columnIndex is an integer variable specifying which column in _rowArray the user wants to order by. While debugging, I can see that the sortedRows holds the same sequence as _rowArray in the same order, immediately following the LINQ statement. I have also tried:

_rowArray = _rowArray.OrderBy(r => r[columnIndex]).ToArray();

and have tried creating a DataView (view) and done this:

view.Sort = m_data.Tables[0].Columns[columnIndex].ColumnName + " ASC";

...but that hasn't worked. Anyone offer any insight?

score 1 · Answer 1 · answered Oct 19 '12 at 09:51

1

Have you tried parsing the string to int before ordering them?

_rowArray = _rowArray.OrderBy(r => int.Parse(r[columnIndex])).ToArray();

answered Oct 19 '12 at 09:51

Samy Arous

6,794
13
20

That presents its own problems. Firstly, they could be of any value type, not just ints. Secondly, they could be null. Also, I'd need to cast the r[columnIndex] to a string before parsing to Double, int etc. – MrShoes Oct 19 '12 at 10:07
Well, if you don't know the value type, you can't simply expect it to be sorted as integer :). The other alternative would be to do the sorting the old way using a Comparer. – Samy Arous Oct 19 '12 at 10:19
I can get the data type using var dataType = dataGridView1.Columns[columnIndex].ValueType; – MrShoes Oct 19 '12 at 10:43
What I meant is that not every value type can be mapped to an integer value (unless you hash them of course). You will most likely need a different sort method depending to the ValueType. – Samy Arous Oct 19 '12 at 10:46
OK. I've tried the below as a hash and confirmed the data case "double" statement is true, but I'm getting an exception due to the string being in incorrect format (ie null). var dataType = dataGridView1.Columns[columnIndex].ValueType; switch (dataType.Name.ToLower()) { case "double": _rowArray = _rowArray.OrderBy(r => double.Parse(r[columnIndex].ToString())).ToArray(); break; } – MrShoes Oct 19 '12 at 10:59
This is most likely due to your Culture Settings. In the parse function, you can specify a IFormatProvider. This should give the exact same format that you are getting from the DB – Samy Arous Oct 19 '12 at 11:57

score 0 · Answer 2 · edited May 23 '17 at 12:12

Thanks to help from lcfseth, and also the thread here, I've solved this, although it's pretty ugly.

I used the Parse method from the other thread:

public static T Parse<T>(object value)
{
    try { return (T)System.ComponentModel.TypeDescriptor.GetConverter(typeof(T)).ConvertFrom(value.ToString()); }
    catch { return default(T); }
}

then my own method has become:

private void SortRows(int columnIndex, ListSortDirection direction)
        {
            if ((_rowArray == null) || (!_rowArray.Any()))
                return;

            dataGridView1.EndEdit();

            RemoveRowDefinitions();

            if (direction == ListSortDirection.Ascending)
            {
                var dataType = dataGridView1.Columns[columnIndex].ValueType;
                try
                {
                    switch (dataType.Name.ToLower())
                    {
                        case "double":
                            _rowArray = _rowArray.OrderBy(r => Parse<double?>(r[columnIndex].ToString())).ToArray();
                            break;
                        case "int32":
                            _rowArray = _rowArray.OrderBy(r => Parse<int?>(r[columnIndex].ToString())).ToArray();
                            break;
                        case "datetime":
                            _rowArray = _rowArray.OrderBy(r => Parse<DateTime?>(r[columnIndex].ToString())).ToArray();
                            break;
                        default:
                            _rowArray = _rowArray.OrderBy(r => r[columnIndex].ToString()).ToArray();
                            break;
                    }
                }
                catch(Exception ex)
                {
                    throw new Exception("Cannot sort on the data type '" + dataType.Name + "'", ex);
                }              
            }

            if (direction == ListSortDirection.Descending)
            {
                var dataType = dataGridView1.Columns[columnIndex].ValueType;
                try
                {
                    switch (dataType.Name.ToLower())
                    {
                        case "double":
                            _rowArray = _rowArray.OrderByDescending(r => Parse<double?>(r[columnIndex].ToString())).ToArray();
                            break;
                        case "int32":
                            _rowArray = _rowArray.OrderByDescending(r => Parse<int?>(r[columnIndex].ToString())).ToArray();
                            break;
                        case "datetime":
                            _rowArray = _rowArray.OrderByDescending(r => Parse<DateTime?>(r[columnIndex].ToString())).ToArray();
                            break;
                        default:
                            _rowArray = _rowArray.OrderByDescending(r => r[columnIndex].ToString()).ToArray();
                            break;
                    }
                }
                catch (Exception ex)
                {
                    throw new Exception("Cannot sort on the data type '" + dataType.Name + "'", ex);
                }                    
            }

            dataGridView1.Refresh();
            ApplyRowDefinitions();
            GC.Collect();
        }

OrderBy named index

2 Answers2