Sorting group rows by date in RadGridView

Environment

Product Version	Product	Author
2020.1.113	RadGridView for WinForms	Nadya Karaivanova

Description

This tutorial demonstrates how to sort rows in RadGridView when it is grouped by date.

Solution

By default, when you perform grouping, RadGridView sorts the created group rows alphabetically (see Sorting Group Rows article). If you want to sort groups by another criteria it is suitable to use a GroupComparer class. Thus, you can parse each group key to DateTime format and compare the date instead of the string.

A full code snippet is illustrated below:

 public Form1()
        {
            InitializeComponent();

            DataTable dt = new DataTable();
            dt.Columns.Add("Id", typeof(int));
            dt.Columns.Add("StartDate", typeof(DateTime));
            dt.Columns.Add("EndDate", typeof(DateTime));
            DateTime date = new DateTime(2020, 2, 10);
            for (int i = 1; i < 20; i++)
            {
                dt.Rows.Add(i, date.AddHours(i * 12), date.AddDays(i + 1));
            }
            radGridView1.DataSource = dt;

            radGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;
            radGridView1.Columns[1].FormatString = "{0:dd/MM/yyyy}";
            radGridView1.Columns[2].FormatString = "{0:dd/MM/yyyy}";

            radGridView1.MasterTemplate.GroupPredicate = PerformGrouping;
            radGridView1.MasterTemplate.GroupComparer = new GroupComparer();

        }

        public class GroupComparer : IComparer<Group<GridViewRowInfo>>
        {
            public int Compare(Group<GridViewRowInfo> x, Group<GridViewRowInfo> y)
            {
                if (x.GetType().Name != y.GetType().Name)
                {
                    return x is DataItemGroup<GridViewRowInfo> ? 1 : -1;
                }

                DateTime parsedX;
                DateTime parsedY;
                int result;

                if (DateTime.TryParse(((object[])x.Key).First().ToString(), out parsedX) &&
                    DateTime.TryParse(((object[])y.Key).First().ToString(), out parsedY))
                {
                    result = parsedX.CompareTo(parsedY);
                    DataGroup xGroup = x as DataGroup;
                    if (xGroup != null && xGroup.GroupDescriptor.GroupNames.Count > 0)
                    {
                        if (xGroup.GroupDescriptor.GroupNames.First().Direction == ListSortDirection.Ascending)
                        {
                            return result;
                        }
                    }

                    result = -1 * result;
                    return result;
                }

                return x.Key.ToString().CompareTo(y.Key.ToString());
            }
        }

        private object PerformGrouping(GridViewRowInfo row, int level)
        {
            GroupDescriptor groupDescriptors = this.radGridView1.GroupDescriptors[level];
            object[] key = new object[groupDescriptors.GroupNames.Count];

            for (int k = 0; k < groupDescriptors.GroupNames.Count; k++)
            {
                SortDescriptor descriptor = groupDescriptors.GroupNames[k];
                int index = descriptor.PropertyIndex;

                if (index < 0)
                {
                    continue;
                }

                key[k] = this.GetItemKey(row, descriptor);
            }

            return key;
        }
        private object GetItemKey(GridViewRowInfo item, SortDescriptor descriptor)
        {
            int index = descriptor.PropertyIndex;
            object keyValue = item.Cells[index].Value;

            if (descriptor.PropertyName == "StartDate" || descriptor.PropertyName == "EndDate")
            {
                keyValue = ((DateTime)keyValue).ToShortDateString();
            }

            return keyValue;
        }

Public Class RadForm1
    Public Sub New()
        InitializeComponent()
        Dim dt As DataTable = New DataTable()
        dt.Columns.Add("Id", GetType(Integer))
        dt.Columns.Add("StartDate", GetType(DateTime))
        dt.Columns.Add("EndDate", GetType(DateTime))
        Dim _date As DateTime = New DateTime(2020, 2, 10)

        For i As Integer = 1 To 20 - 1
            dt.Rows.Add(i, _date.AddHours(i * 12), _date.AddDays(i + 1))
        Next

        RadGridView1.DataSource = dt
        RadGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill
        RadGridView1.Columns(1).FormatString = "{0:dd/MM/yyyy}"
        RadGridView1.Columns(2).FormatString = "{0:dd/MM/yyyy}"
        RadGridView1.MasterTemplate.GroupPredicate = AddressOf PerformGrouping
        RadGridView1.MasterTemplate.GroupComparer = New GroupComparer()
    End Sub

    Public Class GroupComparer
        Implements IComparer(Of Group(Of GridViewRowInfo))

        Public Function Compare(x As Group(Of GridViewRowInfo), y As Group(Of GridViewRowInfo)) As Integer Implements IComparer(Of Group(Of GridViewRowInfo)).Compare
            If x.[GetType]().Name <> y.[GetType]().Name Then
                Return If(TypeOf x Is DataItemGroup(Of GridViewRowInfo), 1, -1)
            End If

            Dim parsedX As DateTime
            Dim parsedY As DateTime
            Dim result As Integer

            If DateTime.TryParse((CType(x.Key, Object())).First().ToString(), parsedX) AndAlso DateTime.TryParse((CType(y.Key, Object())).First().ToString(), parsedY) Then
                result = parsedX.CompareTo(parsedY)
                Dim xGroup As DataGroup = TryCast(x, DataGroup)

                If xGroup IsNot Nothing AndAlso xGroup.GroupDescriptor.GroupNames.Count > 0 Then

                    If xGroup.GroupDescriptor.GroupNames.First().Direction = ListSortDirection.Ascending Then
                        Return result
                    End If
                End If

                result = -1 * result
                Return result
            End If

            Return x.Key.ToString().CompareTo(y.Key.ToString())
        End Function
    End Class

    Private Function PerformGrouping(ByVal row As GridViewRowInfo, ByVal level As Integer) As Object
        Dim groupDescriptors As GroupDescriptor = Me.RadGridView1.GroupDescriptors(level)
        Dim key As Object() = New Object(groupDescriptors.GroupNames.Count - 1) {}

        For k As Integer = 0 To groupDescriptors.GroupNames.Count - 1
            Dim descriptor As SortDescriptor = groupDescriptors.GroupNames(k)
            Dim index As Integer = descriptor.PropertyIndex

            If index < 0 Then
                Continue For
            End If

            key(k) = Me.GetItemKey(row, descriptor)
        Next

        Return key
    End Function

    Private Function GetItemKey(ByVal item As GridViewRowInfo, ByVal descriptor As SortDescriptor) As Object
        Dim index As Integer = descriptor.PropertyIndex
        Dim keyValue As Object = item.Cells(index).Value

        If descriptor.PropertyName = "StartDate" OrElse descriptor.PropertyName = "EndDate" Then
            keyValue = (CType(keyValue, DateTime)).ToShortDateString()
        End If

        Return keyValue
    End Function
End Class